Antitrust Reform and Big Tech Firms
March 22, 2023
Antitrust has become a hot topic. After decades evolving in technocratic obscurity, competition
policy now commands the attention of lawmakers, academics, and the general public.
Jay B. Sykes
Legislative Attorney
One of the driving forces behind this trend has been the rise of a handful of large technology

firms: Facebook (now Meta Platforms), Google, Amazon, and Apple. While these “Big Tech”
companies have revolutionized the daily lives of billions, they also are accused of obtaining and

solidifying dominant positions through anticompetitive conduct.
Meta is currently defending a Federal Trade Commission (FTC) lawsuit that seeks to unwind its acquisitions of the photo-
sharing service Instagram and the messaging app WhatsApp.
Google is embroiled in litigation with the Department of Justice (DOJ), state attorneys general, and private plaintiffs over
alleged exclusionary conduct related to its search engine, app distribution on Android mobile devices, and its
digital-advertising businesses.
Amazon has faced lawsuits challenging pricing restrictions it imposes on third-party merchants. Some commentators have
also alleged that the company has engaged in anticompetitive tying, predatory pricing, and unfair self-preferencing.
Several of Apple’s practices have attracted scrutiny, including the firm’s restrictions on the distribution of iOS apps, its use
of competitively sensitive information derived from third-party app developers, and its treatment of its proprietary apps.
Litigation challenging the iPhone maker’s app-distribution restrictions is currently pending before the Ninth Circuit.
Some lawmakers have also expressed concern about the large number of acquisitions that the Big Tech firms have engaged in
over the past decade. In particular, they have worried about the possibility that some of these transactions eliminated sources
of potential or nascent competition.
Many of these concerns have prompted calls for legal reform. Some commentators have argued that ex post adjudication is
ill-equipped to grapple with competition issues in platform markets that have tipped in favor of a single dominant firm. Other
critiques of the existing framework focus on specific doctrinal rules or the alleged shortcomings of the consumer-welfare
standard—a general normative benchmark that has heavily influenced current law.
For their part, defenders of antitrust adjudication have emphasized the differences between the Big Tech firms. This
heterogeneity, they contend, counsels in favor of the fact-specific approach employed by current law and against categorical
regulatory treatment. Supporters of the consumer-welfare standard argue that it provides a principled and coherent
decision-making framework, in contrast to alternative regimes that would embrace more amorphous goals.
While some reform proposals would adopt special competition regulations for large tech platforms, others would work within
existing antitrust law by adjusting burdens of proof and changing certain doctrinal requirements.
The regulatory route raises questions of policy design—namely, how to scope the relevant regulations and select an
appropriate regulator to administer them. On the issue of scope, two general models have emerged. One would allow a
regulator to designate covered platforms that offer specified services and meet certain quantitative and qualitative criteria.
Designated firms would then be subject to the same set of special competition regulations. The other approach is more
targeted and would apply special regulations to individual markets. With respect to the selection of a regulator, commentators
have proposed giving new authorities to the DOJ and/or FTC, creating a new branch within either of those agencies, or
establishing a standalone digital-platform regulator.
As a substantive matter, proposals to reform the competition laws governing Big Tech firms fall into five categories:
(1) ex ante conduct rules, (2) structural separation and line-of-business restrictions, (3) special merger rules,
(4) interoperability and data-portability mandates, and (5) changes to general antitrust doctrine.
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n 2012, a prominent scholar lamented the diminished significance of antitrust in the United
States.1 Although there was once a flourishing antitrust movement, he argued, the subject
appeared to attract little interest from lawmakers, academics, and the public.2 Political
I candidates rarely mentioned competition issues, opinion polls reflected indifference toward
economic concentration, and the enforcement agencies seemed to operate with a narrow
understanding of antitrust’s scope.3
Since then, things have changed—dramatically. In the past several years, antitrust has resurfaced
as an issue of both popular and political concern.4 The White House has issued an executive order
outlining a “whole-of-government” approach to competition policy;5 advocates of reform have
been appointed to lead the Federal Trade Commission (FTC) and the Department of Justice’s
(DOJ’s) Antitrust Division;6 and Congress has considered a suite of proposals to overhaul various
aspects of antitrust doctrine.7
In the words of one commentator, antitrust now “stands at its most fluid and negotiable moment
in a generation.”8 The subject has not had such political salience, another contends, since 1912.9
Interest in reform has been wide-ranging: “[e]verything is up for grabs, and nothing is free of
scrutiny.”10
One of the driving forces behind this trend has been the rise of a handful of large technology
firms: Facebook (now Meta Platforms), Google, Amazon, and Apple. In 2020, a House
subcommittee released a detailed report (the HJC Report) concluding that the four companies had
obtained and solidified dominant positions through anticompetitive conduct.11 These “Big Tech”
firms have also faced antitrust lawsuits from regulators and private plaintiffs, both in the United
States and abroad.12
This report provides an overview of antitrust issues involving the four Big Tech firms and related
proposals for legislative reform. It is divided into four parts. First, the report provides an
introduction to basic antitrust principles. Second, it reviews selected antitrust allegations against

1 Maurice E. Stucke, Reconsidering Antitrust’s Goals, 53 B.C. L. REV. 551, 553 (2012).
2 Id. at 553-56.
3 Id.
4 Daniel A. Crane, Antitrust’s Unconventional Politics, 104 VA. L. REV. ONLINE 118, 118-21 (2018).
5 Exec. Order No. 14,036, Promoting Competition in the American Economy, 86 Fed. Reg. 36,987, 36,989 (July 14,
2021).
6 Brent Kendall, Senate Confirms Jonathan Kanter as Justice Department Antitrust Chief, WALL ST. J. (Nov. 16, 2021),
https://www.wsj.com/articles/senate-confirms-jonathan-kanter-as-justice-department-antitrust-chief-11637104400;
David McCabe & Cecilia Kang, Biden Names Lina Khan, a Big-Tech Critic, as F.T.C. Chair, N.Y. TIMES (June 15,
2021), https://www.nytimes.com/2021/06/15/technology/lina-khan-ftc.html.
7 See, e.g., Prohibiting Anticompetitive Mergers Act of 2022, S. 3847, 117th Cong. (2022); Platform Competition and
Opportunity Act, S. 3197, 117th Cong. (2021); American Innovation and Choice Online Act, S. 2992, 117th Cong.
(2021); Trust-Busting for the Twenty-First Century Act, S. 1074, 117th Cong. (2021); Competition and Antitrust Law
Enforcement Reform Act of 2021, S. 225, 117th Cong. (2021); Ending Platform Monopolies Act, H.R. 3825, 117th
Cong. (2021).
8 Crane, supra note 4, at 118.
9 Carl Shapiro, Antitrust in a Time of Populism, 61 INT’L J. INDUS. ORG. 714, 715 (2018).
10 ALAN J. DEVLIN, REFORMING ANTITRUST 265 (2021).
11 INVESTIGATION OF COMPETITION IN DIGITAL MARKETS, MAJORITY STAFF REPORT AND RECOMMENDATIONS, SUBCOMM.
ON ANTITRUST, COMMERCIAL AND ADMIN. L. OF THE H. COMM. ON THE JUDICIARY 12-17 (2020) [hereinafter “HJC
REPORT”]. This report lists the Big Tech firms in the same order as the subcommittee’s report.
12 See infra “The Big Tech Firms: A Summary of Selected Antitrust Allegations.”
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the Big Tech companies. Third, it discusses conceptual issues with proposals to reform the
competition laws governing Big Tech. Fourth, the report analyzes the substance of specific
categories of reform proposals.
Antitrust Law: The Basics
The antitrust laws aim to protect economic competition by prohibiting unreasonable restraints of
trade,13 exclusionary conduct by dominant firms,14 and mergers and acquisitions that may
“substantially” lessen competition or “tend to create a monopoly.”15
The following subsections provide a high-level overview of antitrust doctrine to lay the
groundwork for later discussions of competition issues in tech markets and proposals for legal
reform.
Restraints of Trade
Section 1 of the Sherman Act prohibits “every” contract or conspiracy “in restraint of trade.”16
Despite this categorical language, the Supreme Court has interpreted Section 1 to bar only
unreasonable restraints of trade that harm competition.17
Applying this general standard, the Court has identified some types of agreements that are so
likely to be anticompetitive that they are deemed per se illegal, meaning courts need not inquire
into their effects in individual cases.18 Restraints in this category include agreements among
competitors (“horizontal” agreements) to fix prices,19 divide markets,20 and restrain output.21
While some types of agreements are per se illegal under Section 1, most restraints are evaluated
using a standard called the “rule of reason.”22 Under the rule of reason, courts conduct
fact-specific assessments of a defendant’s market power and the details of a challenged
agreement to determine a restraint’s competitive effects.23
This inquiry typically proceeds via a three-step burden-shifting framework. In that framework,
the plaintiff has the initial burden to prove that the challenged restraint has a substantial
anticompetitive effect.24 If the plaintiff does so, the burden shifts to the defendant to show a
procompetitive justification for the restraint.25 If the defendant makes this showing, the burden

13 15 U.S.C. § 1.
14 Id. § 2.
15 Id. § 18.
16 Id. § 1.
17 Texaco Inc. v. Dagher, 547 U.S. 1, 5 (2006).
18 Id.
19 United States v. Socony-Vacuum Oil Co., 310 U.S. 150, 218 (1940).
20 N. Pac. R.R. Co. v. United States, 356 U.S. 1, 5 (1958).
21 NCAA v. Bd. of Regents of Univ. of Okla., 468 U.S. 85, 100 (1984).
22 Ohio v. Am. Express Co. (Amex), 138 S. Ct. 2274, 2283-84 (2018).
23 Id. at 2284. The Supreme Court has explained that a firm has market power if it has the ability to price above
competitive levels, Bd. of Regents, 468 U.S. at 109 n.38, or the power to constrain market output to raise prices, Fortner
Enters. v. U.S. Steel Corp., 394 U.S. 495, 503 (1969).
24 Amex, 138 S. Ct. at 2284.
25 Id.
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shifts back to the plaintiff to demonstrate that the relevant procompetitive benefits could be
reasonably achieved through less anticompetitive means.26 Some courts have also added a fourth
step in which they balance a restraint’s anticompetitive and procompetitive effects.27
Monopolization
While Section 1 of the Sherman Act governs agreements between firms, Section 2 prohibits
dominant companies from engaging in unilateral anticompetitive conduct. In the statutory
parlance, Section 2 makes it unlawful to “monopolize” commerce.28
The monopolization offense has two elements:
1. the possession of monopoly power; and
2. “the willful acquisition or maintenance of that power as distinguished from
growth or development as a consequence of a superior product, business acumen,
or historical accident.”29
The second element is often referred to as “exclusionary” or “anticompetitive” conduct.30
Monopoly Power
The Supreme Court has explained that a firm possesses monopoly power if it has the ability to
“control prices or exclude competition.”31 Although that standard is similar to many descriptions
of market power,32 the Court has clarified that monopoly power under Section 2 of the Sherman
Act requires “something greater” than market power under Section 1.33 Lower courts have thus
concluded that monopoly power entails a large degree of market power.34
Some courts have held that monopoly power can be established through direct evidence of
supra-competitive prices and restricted output.35 However, this type of direct proof is rarely
available.36 As a result, courts typically evaluate allegations of monopoly power by examining a

26 Id.
27 See, e.g., Bhan v. NME Hosps., Inc., 929 F.2d 1404, 1413 (9th Cir. 1991) (acknowledging a possible fourth step); see
also Michael A. Carrier, The Rule of Reason: An Empirical Update for the 21st Century, 16 GEO. MASON L. REV. 827,
827 (2009) (concluding that courts reached a fourth “balancing” step in four percent of rule-of-reason cases decided
between 1977 and 1999). The FTC and some lower courts have also employed an intermediate “quick look” framework
to evaluate restraints that are similar to per se unlawful conduct but exhibit features warranting additional analysis. See
Herbert Hovenkamp, The Rule of Reason, 70 FLA. L. REV. 81, 122-31 (2018) [hereinafter “Hovenkamp, The Rule of
Reason”]. Different courts have described quick-look analysis in different ways, but the basic idea is that some types of
restraints can be condemned without the full rule-of-reason inquiry. Id. at 122-23.
28 15 U.S.C. § 2.
29 United States v. Grinnell Corp., 384 U.S. 563, 570-71 (1966).
30 See, e.g., EINER ELHAUGE, UNITED STATES ANTITRUST LAW AND ECONOMICS 211 (3d ed. 2018).
31 United States v. E.I. du Pont de Nemours & Co., 351 U.S. 377, 391 (1956).
32 See, e.g., Fortner Enters. v. U.S. Steel Corp., 394 U.S. 495, 503 (1969) (defining market power as “the ability of a
single seller to raise price and restrict output”).
33 Eastman Kodak Co. v. Image Tech. Servs., Inc., 504 U.S. 451, 481 (1992).
34 See, e.g., Bacchus Indus., Inc. v. Arvin Indus., Inc., 939 F.2d 887, 894 (10th Cir. 1991); Deauville Corp. v. Federated
Dep’t Stores, Inc., 756 F.2d 1183, 1192 n.6 (5th Cir. 1985).
35 Broadcom Corp. v. Qualcomm Inc., 501 F.3d 297, 307 (3d Cir. 2007); PepsiCo, Inc. v. Coca-Cola Co., 315 F.3d 101,
107 (2d Cir. 2002) (per curiam); Conwood Co. v. U.S. Tobacco Co., 290 F.3d 768, 783 n.2 (6th Cir. 2002).
36 United States v. Microsoft Corp., 253 F.3d 34, 51 (D.C. Cir. 2001) (per curiam).
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market’s structure—in particular, whether a defendant occupies a dominant market share and is
protected by entry barriers.37
These inquiries require a plaintiff to define the boundaries of the relevant product market—an
exercise that turns on the range of items that are “reasonably interchangeable” with the product at
issue.38
The key conceptual issue with market definition is whether buyer substitution to other items
would limit a monopolist in an alleged market from raising prices significantly above competitive
levels.39 If buyer substitution would constrain even a firm with a dominant share of an alleged
market from raising prices significantly, the relevant legal test prescribes that the market must be
expanded until buyer substitution of other items would not offer such a constraint.40
Courts have relied on a variety of factors in defining markets, including functional similarities
and differences between separate items, cross-elasticities of demand (i.e., the extent to which the
quantity demanded of one item changes in response to price changes for another item), price
differences, price discrimination, and price trends.41
Once a market has been defined, courts usually look to a defendant’s share of that market to
assess claims of monopoly power.42 The case law has not identified a definitive point at which
monopoly power can be inferred, but courts typically require monopolization plaintiffs to prove
that the defendant occupies a market share of 70 percent or more.43
To establish monopoly power, plaintiffs must also show that a defendant’s dominant position is
likely to be durable—for example, with evidence of significant entry barriers.44 Entry barriers
may include legal and regulatory requirements, control of an essential resource, entrenched buyer
preferences, and economies of scale.45 In some digital markets, entry barriers may also emerge
from network effects (whereby a product’s utility increases as it gains more users) and significant
switching costs (high costs that users of a product would face in switching to a substitute).46
Exclusionary Conduct
As noted, the second element of a monopolization claim is exclusionary conduct. The Supreme
Court has described this element as involving “the willful acquisition or maintenance of
[monopoly] power as distinguished from growth or development as a consequence of a superior
product, business acumen, or historical accident.”47

37 Id.
38 United States v. E.I. du Pont de Nemours & Co., 351 U.S. 377, 395 (1956).
39 ELHAUGE, supra note 30, at 240.
40 Id. at 241.
41 MARKET POWER HANDBOOK: COMPETITION LAW AND ECONOMIC FOUNDATIONS, AM. BAR ASS’N 62-74 (2d ed. 2012).
42 See, e.g., U.S. Anchor Mfg., Inc. v. Rule Indus., Inc., 7 F.3d 986, 999 (11th Cir. 1993).
43 U.S. DEP’T OF JUST., COMPETITION AND MONOPOLY: SINGLE-FIRM CONDUCT UNDER SECTION 2 OF THE SHERMAN ACT
21 (2008) (withdrawn May 11, 2009) [hereinafter “DOJ MONOPOLIZATION REPORT”] (collecting cases).
44 See, e.g., Lenox MacLaren Surgical Corp. v. Medtronic, Inc., 762 F.3d 1114, 1123-25 (10th Cir. 2014); W. Parcel
Express v. United Parcel Serv. of Am., Inc., 190 F.3d 974, 975 (9th Cir. 1999).
45 Rebel Oil Co., Inc. v. Atlantic Richfield Co., 51 F.3d 1421, 1439 (9th Cir. 1995).
46 FTC v. Facebook, Inc., 581 F. Supp. 3d 34, 51 (D.D.C. 2022).
47 United States v. Grinnell Corp., 384 U.S. 563, 570-71 (1966).
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As a general standard, many have found that description unhelpful. Businesses often “willfully”
try to obtain monopoly status by developing superior products and by deploying business
acumen.48 The Court’s dichotomy thus offers little clarity on how to distinguish exclusionary
conduct from legitimate competition on the merits.
While academics have made several attempts to develop an alternative general standard,49 courts
have not decisively embraced any of them.50 Instead, the doctrine contains a variety of tests that
govern specific categories of conduct,51 along with a burden-shifting framework that is similar to
the usual rule-of-reason inquiry in Section 1 cases.52
The following subsections review the standards governing particular types of conduct by
dominant firms.
Predatory Pricing
Some monopolization cases involve allegations that a defendant aggressively cut prices in an
attempt to exclude rivals from the market—a practice commonly known as predatory pricing.53
Under the Supreme Court’s Brooke Group test, plaintiffs must make two showings to prevail on a
predatory-pricing claim.54 First, plaintiffs must show that the defendant’s prices fell below an
appropriate measure of its costs.55 Second, plaintiffs must establish a “dangerous probability” that
the defendant will recoup its investment in below-cost prices by raising prices upon the
elimination of competitors.56
These requirements have proven difficult to satisfy. Since the Brooke Group decision,
predatory-pricing claims have rarely made it past summary judgment.57 The Court has defended
the restrictiveness of the relevant criteria by arguing that successful predatory pricing is rare and
by emphasizing the need to avoid deterring procompetitive price cutting.58
Refusals to Deal
Another category of potentially exclusionary conduct involves refusals to deal with rivals. For
example, a dominant firm might control key infrastructure or technology that its competitors need

48 Many commentators have made this point. For one example, see Daniel Francis, Making Sense of Monopolization,
84 ANTITRUST L.J. 779, 779-80 (2022).
49 For an overview, see CHRISTOPHER SAGERS, ANTITRUST 205-08 (3d ed. 2021); DOJ MONOPOLIZATION REPORT, supra
note 43, at 33-47.
50 DOJ MONOPOLIZATION REPORT, supra note 43, at 33.
51 Id. at 49-141; ELHAUGE, supra note 30, at 277-355.
52 Viamedia, Inc. v. Comcast Corp., 951 F.3d 429, 463-64 (7th Cir. 2020); United States v. Microsoft Corp., 253 F.3d
34, 58-59 (D.C. Cir. 2001) (per curiam).
53 ELHAUGE, supra note 30, at 277.
54 Brooke Grp. Ltd. v. Brown & Williamson Tobacco Corp., 509 U.S. 209, 222-24 (1993).
55 Id. at 222.
56 Id. at 224.
57 Lina M. Khan, Amazon’s Antitrust Paradox, 126 YALE L.J. 710, 730 & n.107 (2017) [hereinafter “Khan, Amazon’s
Antitrust Paradox”].
58 Brooke Grp., 509 U.S. at 226.
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to effectively compete, in which case a denial of access to the relevant property may harm
competition.59
The Supreme Court has held that monopolists have a duty to deal with rivals only in a narrow set
of circumstances. In Aspen Skiing Co. v. Aspen Highlands Skiing Corp., the Court affirmed
Section 2 liability because the only plausible motivation for a monopolist’s refusal to deal was a
desire to drive its competitor out of business.60 In that case, the defendant’s refusal was not
motivated by efficiency concerns and instead represented a sacrifice of short-term profits to
eliminate a rival.61
In its 2004 decision in Verizon Communications Inc. v. Trinko, however, the Court characterized
its holding in Aspen Skiing as lying “at or near the outer boundary” of Section 2 liability.62 In
rejecting a refusal-to-deal claim, Trinko distinguished Aspen Skiing on the grounds that the
monopolist in the latter decision had terminated “a voluntary (and thus presumably profitable)
course of dealing,” which suggested a willingness to sacrifice short-term profits for an
anticompetitive end.63 The Court also emphasized that the monopolist in Aspen Skiing refused to
deal with its rival even if compensated at the prices it charged to other customers, which
“revealed a distinctly anticompetitive bent.”64
Based on these decisions, some lower courts have concluded that refusal-to-deal plaintiffs must
establish that a defendant’s refusal entailed a sacrifice of short-term profits for an exclusionary
purpose.65 Some courts have also required plaintiffs to establish this type of profit sacrifice with
proof that the defendant terminated a voluntary course of dealing.66
Many circuit courts have also accepted a specific theory of refusal-to-deal liability called the
“essential facilities” doctrine, which the Supreme Court has declined to either recognize or
repudiate.67 To establish liability under the essential-facilities doctrine, plaintiffs must establish:
1. the control of an “essential facility” by a monopolist;
2. an inability to “practically or reasonably” duplicate the facility;
3. the denial of the use of the facility to a competitor; and
4. the feasibility of providing access to the facility.68
While that doctrine remains on the books as a formal matter,69 two commentators have described
the Supreme Court’s treatment of it as inflicting “death by dicta.”70 Its viability thus remains
uncertain.

59 SAGERS, supra note 49, at 219.
60 Aspen Skiing Co. v. Aspen Highlands Skiing Corp., 472 U.S. 585, 608-11 (1985).
61 See id.
62 540 U.S. 398, 409 (2004).
63 Id.
64 Id.
65 E.g., Novell, Inc. v. Microsoft Corp., 731 F.3d 1064, 1075 (10th Cir. 2013) (Gorsuch, J.); Covad Commc’ns Co. v.
Bell Atl. Corp., 398 F.3d 666, 675 (D.C. Cir. 2005); but see Viamedia Inc. v. Comcast Corp., 951 F.3d 429, 462
(7th Cir. 2020) (concluding that profit sacrifice is relevant but not always dispositive for refusal-to-deal liability).
66 E.g., Novell, 731 F.3d at 1075.
67 Trinko, 540 U.S. at 410-11.
68 MCI Commc’ns Corp. v. AT&T Co., 708 F.2d 1081, 1132-33 (7th Cir. 1983).
69 See ELHAUGE, supra note 30, at 353 n.91 (collecting circuit court decisions recognizing the doctrine).
70 Brett Frischmann & Spencer Weber Waller, Revitalizing Essential Facilities, 75 ANTITRUST L.J. 1, 3 (2008); see also
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Tying
Tying arrangements are vertical restraints of trade that can be challenged under several provisions
of the antitrust laws, including Sections 1 and 2 of the Sherman Act.71 Tying involves a refusal to
sell one product (the tying product) unless buyers also purchase another product (the tied product)
from the seller.72
The traditional concern with tying arrangements is that they may allow a firm with market power
for the tying product to harm competition in and even monopolize the tied product market.73
Tying may also help a dominant firm preserve a monopoly in the tying market by eliminating
potential rivals that may enter via the tied market.74
Possible redeeming efficiencies of tying include reputation protection and economies of
production or distribution. For example, tying may dissuade consumers from using an inferior
substitute to the tied product with the tying product, thereby mitigating the risk of reputational
damage to a seller’s brand.75 Producing and selling different products together may also reduce
production, marketing, and distribution costs.76
In addition, tying arrangements may encourage investment by allowing a firm to convert fixed
costs into variable costs. For example, a franchisor might sell a franchise for less than its market
value but employ a tying arrangement to secure overcharges on goods distributed through the
franchise.77 This type of arrangement might encourage investment by decreasing a franchisee’s
upfront costs.78
Contractual tying arrangements are governed by what is often called a rule of quasi-per-se
illegality, though some have described that label as a misnomer.79 While different circuit courts

HERBERT HOVENKAMP, FEDERAL ANTITRUST POLICY: THE LAW OF COMPETITION AND ITS PRACTICE 337 (4th ed. 2011)
(concluding that “[n]ot many essential facility claims will survive” post-Trinko); Khan, Amazon’s Antitrust Paradox,
supra note 57, at 801 (noting that commentators have wondered whether the essential-facilities doctrine is now “a dead
letter”).
71 HOVENKAMP, supra note 70, at 435.
72 ELHAUGE, supra note 30, at 409.
73 CHIARA FUMAGALLI, MASSIMO MOTTA & CLAUDIO CALCAGNO, EXCLUSIONARY PRACTICES: THE ECONOMICS OF
MONOPOLISATION AND ABUSE OF DOMINANCE 352 (2018). For a discussion of the Chicago School’s influential critique
of this “leverage” theory of harm and responses to that critique, see id. at 363-99.
74 Id. at 386-88. For additional theories of harm involving tying, see HOVENKAMP, supra note 70, at 436.
75 ELHAUGE, supra note 30, at 419.
76 FUMAGALLI, et al., supra note 73, at 353.
77 Erik Hovenkamp & Herbert J. Hovenkamp, Tying Arrangements and Antitrust Harm, 52 ARIZ. L. REV. 925, 964
(2010).
78 Id. Some commentators have argued that “variable proportion ties”—whereby consumers purchase a durable tying
product (e.g., a printer) and amounts of the tied product (e.g., ink) that vary with their use of the tying product—may
also increase welfare in certain circumstances. Id. at 951-52. Firms may use variable proportion ties to lower the price
for the tying product while raising the price of the tied product, benefitting low-volume users and harming high-volume
users. Id. Net welfare effects may thus depend on the number of consumers who would not have purchased the tying
product absent the price reduction. Id. Some commentators have analogized certain conduct in tech markets to variable
proportion ties. For example, some have argued that restrictions on app distribution may allow Apple to cut iPhone
prices, meaning high-intensity app users effectively subsidize low-intensity users. Thomas A. Lambert, Addressing Big
Tech’s Market Power: A Comparative Institutional Analysis, 75 SMU L. REV. 73, 104 & n.182 (2022). For an
argument that variable proportion ties are typically welfare-reducing, see Einer Elhauge, Rehabilitating Jefferson
Parish: Why Ties Without a Substantial Foreclosure Share Should Not Be Per Se Legal, 80 ANTITRUST L.J. 463, 476-86
(2016).
79 See, e.g., ELHAUGE, supra note 30, at 420-21.
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have adopted different formulations of the relevant legal test, many of the inquiries are similar.80
One commentator has summarized the doctrine as establishing the following requirements for a
tying claim:
1. The defendant offered two distinct products;
2. The defendant conditioned the sale of one product (the tying product) on the
purchase of the other product (the tied product);
3. The defendant possessed sufficient economic power in the tying product market
to coerce purchasers into acceptance of the tied product; and
4. The defendant’s conduct affected a “not insubstantial” amount of interstate
commerce in the tied product.81
Some courts have also required plaintiffs to demonstrate that a tying arrangement had
anticompetitive effects in the tied product market.82
Although the above test governs most contractual tying arrangements, different standards have
been applied to so-called technological ties, whereby a firm physically integrates separate
products or designs its products in a way that makes them difficult to use with those offered by
other firms.83
In its 2001 decision in United States v. Microsoft, for example, the D.C. Circuit held that a
technological tie involving a computer operating system and a web browser was governed by the
rule of reason, rather than the traditional rule of quasi-per-se illegality.84 Several other courts
have taken a permissive approach to product-design decisions and accepted arguments that
challenged technological ties represented procompetitive quality improvements.85
Exclusive Dealing
Like tying, exclusive-dealing arrangements are vertical restraints that can be challenged under
both Section 1 and Section 2 of the Sherman Act.86 Exclusive dealing occurs when a firm limits
the freedom of buyers or sellers to deal with other companies.87 For example, a seller might offer
widgets on the condition that purchasers obtain all of their widgets from the seller.88

80 HOVENKAMP, supra note 70, at 435 (explaining that “[i]n operation the tests are similar,” but that some courts have
combined elements that other courts recognize as separate requirements).
81 Id.
82 E.g., Kaufman v. Time Warner, 836 F.3d 137, 141 (2d Cir. 2016); Amey, Inc. v. Gulf Abstract & Title Inc., 758 F.2d
1486, 1503 (11th Cir. 1985); Driskill v. Dallas Cowboys Football Club, Inc., 498 F.2d 321, 323 (5th Cir. 1974).
83 DOJ MONOPOLIZATION REPORT, supra note 43, at 33.
84 253 F.3d 34, 89-90 (D.C. Cir. 2001) (per curiam).
85 See John M. Newman, Anticompetitive Product Design in the New Economy, 39 FLA. ST. U. L. REV. 681, 714-23
(2012) (summarizing the case law).
86 HOVENKAMP, supra note 70, at 478. Exclusive-dealing agreements can also be challenged under Section 3 of the
Clayton Act. 15 U.S.C. § 14. Some courts and commentators have suggested that analysis of such agreements may vary
based on which provision is invoked. See, e.g., United States v. Dentsply Int’l, Inc., 399 F.3d 181, 197 (3d Cir. 2005)
(concluding that findings in favor of the defendant under Section 1 of the Sherman Act and Section 3 of the Clayton
Act did not preclude Section 2 liability for exclusive dealing); ELHAUGE, supra note 30, at 371 n.1 (explaining that
“some modern courts appear to treat Clayton Act § 3 claims more generously at the margins”). However, the precise
differences between the relevant inquiries are not entirely clear. DOJ MONOPOLIZATION REPORT, supra note 43, at 132.
87 HOVENKAMP, supra note 70, at 478.
88 Id.
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These types of restrictions may raise antitrust concerns if they foreclose enough of the market to
deter entry or deny rivals the ability to achieve scale economies.89 Exclusive dealing may also
raise rivals’ costs by limiting them to inferior inputs or distribution channels.90
Procompetitive justifications for exclusive dealing include the inducement of relationship-specific
investments,91 mitigation of uncertainty about future sales,92 and the encouragement of more
intense competition for distribution, which may result in lower consumer prices.93
In evaluating exclusive-dealing restrictions, courts ordinarily assess the extent of foreclosure, the
duration of the restrictions, and any business justifications for the restrictions.94 Although there
are exceptions, modern courts have tended to require foreclosure of roughly 40 percent of the
market before condemning exclusive dealing.95
Monopoly Leveraging
A firm’s possession of monopoly power has traditionally given rise to concerns that the firm may use that power
to gain a competitive advantage in another market. For many years, the federal courts split over whether Section 2
precluded this type of “monopoly leveraging” in cases where a defendant utilized its monopoly power to harm
competition in—but not reasonably threaten to monopolize—a second market. Elhauge, supra note 30, at 357-58
nn.97-98 (col ecting cases).
In 2004, the Supreme Court rejected one type of leveraging claim, remarking that a lower court had erred to the
extent that it dispensed with the requirement that a plaintiff relying on a leveraging theory establish that the
defendant had a “dangerous probability” of monopolizing a second market. Verizon Commc’ns Inc. v. L. Offs. of Curtis
V. Trinko, LLP, 540 U.S. 398, 410 n.4 (2004) (citation omitted). The Court thus rejected the proposition that a
defendant could violate Section 2 merely by gaining an unfair advantage in a second market.
In its Microsoft decision, however, the D.C. Circuit endorsed what some commentators have called a “defensive
leveraging” or “monopoly maintenance” theory. See United States v. Microsoft Corp., 253 F.3d 34, 67 (D.C. Cir.
2001) (per curiam); Robin Cooper Feldman, Defensive Leveraging in Antitrust, 87 GEO. L.J. 2079 (1999). While
“offensive leveraging” involves a defendant’s use of monopoly power in one market to extract additional profits
from another market, “defensive leveraging” involves the use of monopoly power to gain an advantage in another
market so as to prevent erosion of a primary monopoly. See Feldman, Defensive Leveraging, 87 GEO. L.J. at 2080.
In Microsoft, for example, the D.C. Circuit concluded that Microsoft had leveraged its operating-system monopoly
into the market for web browsers so as to protect its operating-system monopoly. Microsoft, 253 F.3d at 64.
Specifically, Microsoft imposed several restrictions related to its Windows operating system that were designed to
reduce the usage of rival web browsers, which threatened to supplant Windows as platforms for software
development. Id. at 60. The D.C. Circuit held that some of this conduct constituted unlawful monopolization. Id. at
64.
Accordingly, under current monopolization law, an “offensive leveraging” theory requires proof that a defendant’s
conduct raised a “dangerous probability” of monopolizing a second market; simply gaining an unfair advantage in
another market is not sufficient. Trinko, 540 U.S. at 410 n.4. By contrast, “defensive leveraging”—whereby a
monopolist’s leveraging of its monopoly power into a second market helps preserve its primary monopoly—may
be a viable theory of harm, even without proof that the defendant threatens to monopolize the second market.
See Microsoft, 253 F.3d at 64, 80-84.

89 FUMAGALLI, et al., supra note 73, at 239-62.
90 HOVENKAMP, supra note 70, at 479-80.
91 ELHAUGE, supra note 30, at 375.
92 Id. at 374.
93 Benjamin Klein & Kevin M. Murphy, Exclusive Dealing Intensifies Competition for Distribution, 75 ANTITRUST L.J.
433 (2008).
94 Barry Wright Corp. v. ITT Grinnell Corp., 724 F.2d 227, 236 (1st Cir. 1983) (Breyer, J.).
95 SAGERS, supra note 49, at 173 (collecting cases).
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Mergers & Acquisitions
The antitrust laws also place limitations on mergers and acquisitions.96 Section 7 of the Clayton
Act prohibits mergers whose effect “may be substantially to lessen competition, or to tend to
create a monopoly.”97 Though less common, Section 2 of the Sherman Act can also been used to
challenge mergers that help a firm acquire or maintain monopoly power.98
Analysis of mergers varies based on the relationship between the merging parties—specifically,
based on whether a merger is horizontal, vertical, or conglomerate.
Horizontal and Vertical Mergers
Like horizontal restraints of trade, horizontal mergers involve firms that compete in the same
market.99 These types of deals raise two primary types of concerns. First, horizontal mergers may
have unilateral anticompetitive effects—that is, they may allow the merged firm to raise prices
and reduce output irrespective of the conduct of other firms.100 Second, horizontal mergers may
produce coordinated anticompetitive effects by creating market structures that facilitate collusion
or oligopoly pricing.101
In contrast, vertical mergers involve firms at different stages of the same chain of supply or
distribution.102 These transactions receive less exacting scrutiny than horizontal mergers, because
they do not eliminate direct competitors and often generate efficiencies.103
The primary concern with vertical mergers is the possibility that such transactions may foreclose
sources of supply or distribution previously available to rivals.104 For example, a vertical merger
might give the merged entity the incentive and ability to charge rivals higher prices for inputs or
raise rivals’ costs of distribution.105 At the extreme, a merged firm may refuse to deal with rivals
altogether. Without meaningful alternative sources of supply or distribution, the merged firm’s
rivals may face competitive difficulties. Foreclosure may also raise entry barriers by requiring a
firm’s prospective competitors to enter at two levels of the market rather than one.106
Vertical mergers may also raise concerns if they give a firm access to competitively sensitive
information about rivals or facilitate collusion by allowing the merged entity to monitor
compliance with tacit pricing agreements.107

96 For ease of discussion, this report will refer to both mergers and acquisitions as “mergers.”
97 15 U.S.C. § 18.
98 United States v. Grinnell Corp., 384 U.S. 563, 576 (1966); Fraser v. Major League Soccer, LLC, 284 F.3d 47, 61
(1st Cir. 2002); BRFHH Shreveport, LLC v. Willis Knighton Med. Ctr., 176 F. Supp. 3d 606, 619 (W.D. La. 2016).
99 ELHAUGE, supra note 30, at 705.
100 DEP’T OF JUST. & FED. TRADE COMM’N, HORIZONTAL MERGER GUIDELINES § 6 (2010) [hereinafter “HORIZONTAL
MERGER GUIDELINES”].
101 Id. § 7.
102 SAGERS, supra note 49, at 293.
103 DANIEL A. CRANE, ANTITRUST 164 (2014).
104 DEP’T OF JUST. & FED. TRADE COMM’N, VERTICAL MERGER GUIDELINES § 4 (2020) [hereinafter “VERTICAL MERGER
GUIDELINES”].
105 Id.
106 Id.
107 Id. §§ 4-5.
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In litigation challenging horizontal and vertical mergers, the plaintiff bears the initial burden of
establishing a prima facie case that a merger will substantially lessen competition in the relevant
market.108 In horizontal-merger cases, plaintiffs can discharge this burden by establishing that a
merger would lead to undue levels of market concentration.109
Vertical-merger doctrine does not offer plaintiffs a similar shortcut, because vertical mergers do
not result in immediate changes in market share.110 Instead, plaintiffs challenging vertical mergers
must make a fact-specific showing that a transaction is likely to be anticompetitive.111 While the
case law on vertical mergers is thin, this prima facie case will often involve the concerns
discussed above: foreclosure, raising rivals’ costs, and access to competitively sensitive
information.112
If a merger plaintiff carries its initial burden, then the defendant must present evidence that the
prima facie case inaccurately predicts the merger’s competitive effects or discredit the evidence
underlying that case.113 For example, a defendant in a horizontal-merger case might argue that the
plaintiff’s proposed market is poorly defined, that the entry of other firms will discipline its
pricing power, or that the merger will create efficiencies that offset any anticompetitive effects.114
In a vertical-merger case, a defendant may contend that it lacks incentives to foreclose rivals, that
rivals have adequate alternative sources of supply or distribution, or that the merger would
produce efficiencies (e.g., by eliminating double marginalization).115
Upon rebuttal of a prima facie case, the burden of producing further evidence of anticompetitive
harm shifts back to the plaintiff and merges with the burden of persuasion.116
Conglomerate Mergers
Conglomerate mergers are mergers that are neither horizontal nor vertical.117 Challenges to such
mergers are rare.118 One theory of harm in conglomerate cases, however, is particularly relevant
to tech markets: the elimination of potential competition.
Mergers between potential competitors can raise two types of concerns. First, if the perception
that a potential competitor may enter a market constrains a firm’s pre-merger pricing behavior,
then allowing the firm to acquire the potential competitor eliminates that constraint.119 In the

108 United States v. AT&T, Inc., 916 F.3d 1029, 1032 (D.C. Cir. 2019) (vertical merger); United States v. Baker
Hughes, Inc., 908 F.2d 981, 982-83 (D.C. Cir. 1990) (horizontal merger).
109 See, e.g., FTC v. H.J. Heinz Co., 246 F.3d 708, 715 (D.C. Cir. 2001).
110 AT&T, 916 F.3d at 1032.
111 Id.
112 VERTICAL MERGER GUIDELINES, supra note 104, at § 4.
113 United States v. Anthem, 855 F.3d 345, 349 (D.C. Cir. 2017).
114 Herbert J. Hovenkamp & Carl Shapiro, Horizontal Mergers, Market Structure, and Burdens of Proof, 127 YALE L.J.
1996, 1997 (2018).
115 VERTICAL MERGER GUIDELINES, supra note 104, at §§ 4, 6. By allowing a downstream firm to access inputs at cost
instead of paying a markup, vertical mergers may eliminate the “double marginalization” that occurs when two firms
within a supply chain each mark-up their prices. Id. § 6. The elimination of double marginalization is a key
procompetitive benefit that is often cited in defense of vertical mergers. See id.
116 Baker Hughes, 908 F.2d at 983.
117 ELHAUGE, supra note 30, at 811.
118 Id. at 812; SAGERS, supra note 49, at 321.
119 ELHAUGE, supra note 30, at 811.
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doctrine, this concern is known as the elimination of “perceived potential competition.”120
Second, if a potential competitor actually would have entered the relevant market, then a merger
would eliminate actual future competition, irrespective of whether the potential competitor
constrained pre-merger behavior.121 This concern is called the elimination of “actual potential
competition.”122
The Supreme Court has held that the elimination of perceived potential competition may render a
merger unlawful, but has not expressly recognized the elimination of actual potential competition
as a viable theory of harm.123
The Court has identified several requirements for a perceived-potential-competition claim. A
plaintiff bringing such a claim must show that:
 the relevant market is highly concentrated;
 the potential competitor has the “characteristics, capabilities, and economic
incentive to render it a perceived potential de novo entrant”; and
 the potential competitor “in fact tempered oligopolistic behavior” by market
participants.124
While the Court has declined to resolve the validity of the actual-potential-competition doctrine,
it has explained that plaintiffs relying on that theory must establish that:
 the relevant market is highly concentrated;
 the potential competitor has “feasible means” of entry other than through the
merger; and
 the potential competitor’s entry offers a “substantial likelihood” of
deconcentrating the market or producing other significant procompetitive
effects.125
Lower courts have taken different approaches to actual-potential-competition claims. While the
Eighth Circuit has accepted the theory,126 other courts have declined to resolve its viability.127
Lower courts are also divided on the evidentiary requirements in actual-potential-competition
cases. Some courts require plaintiffs to show that an actual potential competitor “probably” would
have entered the relevant market or use some variation of that language.128 Others have required a

120 Id.
121 Id.
122 Id. Arguably, the elimination of potential competition is a horizontal theory of harm, because it involves the claim
that a potential competitor would likely enter the acquirer’s market or that the acquirer perceives the potential
competitor as being likely to enter its market. SAGERS, supra note 49, at 321 n.45. As discussed above, however,
challenges based on these theories are evaluated under different standards than challenges to other types of horizontal
mergers.
123 United States v. Marine Bancorporation, Inc., 418 U.S. 602, 624-25 (1974).
124 Id.
125 Id. at 633.
126 Yamaha Motor Co. v. FTC, 657 F.2d 971, 977 (8th Cir. 1981).
127 Fraser v. Major League Soccer, LLC, 284 F.3d 47, 61 (1st Cir. 2002); Tenneco, Inc. v. FTC, 689 F.2d 346, 355
(2d Cir. 1982); FTC v. Atl. Richfield Co., 549 F.2d 289, 294 (4th Cir. 1977).
128 FTC v. Steris Corp., 133 F. Supp. 3d 962, 978 (N.D. Ohio 2015); see also Yamaha Motor, 657 F.2d at 977
(“probably”); Tenneco, 689 F.2d at 355 (“would likely”).
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“reasonable probability” of entry129—a standard that one court has construed as more demanding
than a mere “probability” or “more likely than not” test.130 Another court has demanded “clear
proof” of entry but for the merger.131 Some courts have further required that the potential
competitor be one of only a few potential entrants.132
The Goals of Antitrust
As the above discussion makes clear, the text of the antitrust laws is very general. The operative
phrases of the core statutes—“restraint of trade,” “monopolize,” and “substantially . . . lessen
competition”—are generic and undefined. One commentator has observed that “[n]owhere else in
the United States code are so few words used to regulate so much.”133 Many scholars also agree
that the relevant legislative history offers little guidance as to the content of the key statutory
prohibitions.134
The courts have responded to this indeterminacy by treating the antitrust laws as common-law
statutes that vest the judiciary with broad powers to shape competition policy in response to new
economic learning and conditions.135 In addition to giving judges the power to craft specific
doctrinal rules, the flexibility of the antitrust laws leaves courts with a need to identify a
normative benchmark to guide decision-making.136
The relevant lodestar has changed in the course of antitrust history. For much of the 20th century,
courts interpreted the antitrust laws as serving various goals, including the dispersion of economic
power, the protection of small businesses, the preservation of open markets and economic liberty,
the elimination of concentrated political power, and the minimization of wealth transfers from
consumers and producers to large firms.137

129 Mercantile Tex. Corp. v. Bd. of Govs. of the Fed. Res. Sys., 638 F.2d 1255, 1268-69 (5th Cir. 1981); United States
v. Siemens Corp., 621 F.2d 499, 506 (2d Cir. 1980).
130 Mercantile Tex. Corp., 638 F.2d at 1268-69; see also Order Denying Plaintiff’s Motion for Preliminary Injunction at
41, FTC v. Meta Platforms Inc., No. 5:22-cv-04325 (N.D. Cal. Jan. 31, 2023) (adopting the “reasonable probability”
standard, as clarified by the Fifth Circuit to mean “a likelihood noticeably greater than fifty percent”).
131 Atlantic Richfield Co., 549 F.2d at 300.
132 E.g., Mercantile Tex. Corp., 638 F.2d at 1267.
133 Herbert Hovenkamp, The Text of the Antitrust Laws 3 (U. Penn. Inst. for L. & Econ. Rsch. Paper No. 23-01, 2023),
https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4277914.
134 Daniel A. Crane, Antitrust Antitextualism, 96 NOTRE DAME L. REV. 1205, 1206 n.2 (2021); see also United States v.
Tans-Mo. Freight Ass’n, 166 U.S. 290, 318 (1897) (“Looking simply at the history of the [Sherman] bill from the time
it was introduced in the senate until it was finally passed, it would be impossible to say what were the views of a
majority of the members of each house in relation to the meaning of the act. . . . All that can be determined from the
debates and reports is that various members had various views, and we are left to determine the meaning of this act, as
we determine the meaning of other acts, from the language used therein.”).
135 See, e.g., Leegin Creative Leather Prods., Inc. v. PSKS, Inc., 551 U.S. 877, 899 (2007) (“From the beginning the
Court has treated the Sherman Act as a common-law statute. . . . Just as the common law adapts to modern
understanding and greater experience, so too does the Sherman Act’s prohibition on ‘restraint[s] of trade’ evolve to
meet the dynamics of present economic conditions.”) (brackets in original); Nat’l Soc’y of Pro. Eng’rs v. United States,
435 U.S. 679, 688 (1978) (explaining that Congress “expected the courts to give shape to [the Sherman Act’s] broad
mandate by drawing on common-law tradition”).
136 See, e.g., ROBERT H. BORK, THE ANTITRUST PARADOX: A POLICY AT WAR WITH ITSELF 50 (1978) (“[A]ntitrust policy
cannot be made rational until we are able to give a firm answer to one question: What is the point of the law—what are
its goals? Everything else follows from the answer we give. . . . Only when the issue of goals has been settled is it
possible to frame a coherent body of substantive antitrust rules.”); Stucke, supra note 1, at 557 (making a similar
point).
137 See, e.g., Stucke, supra note 1, at 560-62; Eleanor M. Fox, Modernization of Antitrust: A New Equilibrium, 66
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In a 1945 monopolization case, for example, Judge Learned Hand remarked that “great industrial
consolidations are inherently undesirable, regardless of their economic results,” noting that one of
the purposes of the Sherman Act was to “put an end to great aggregations of capital because of
the helplessness of the individual before them.”138
The Supreme Court embraced similar views during the relevant period. In a 1962 merger
decision, it explained that the Clayton Act was intended “to promote competition through the
protection of viable, small, locally owned business,” even if “occasional higher costs and prices
might result from the maintenance of fragmented industries and markets.”139
Applying these principles, mid-century courts condemned a wide range of practices as per se
Sherman Act violations,140 took a skeptical approach to vertical integration,141 and blocked
horizontal mergers that would be unlikely to draw the attention of regulators today.142
In the 1970s and 1980s, things began to change. During that time, courts abandoned small
business protectionism and the socio-political effects of concentrated economic power as salient
considerations in antitrust decision-making.143 In place of the mid-century “multiple goals”
approach, the concept of consumer welfare came to occupy a central place in antitrust doctrine,144
though its precise meaning and accuracy as a descriptive principle remain contested.145

CORNELL L. REV. 1140, 1182 (1981).
138 United States v. Aluminum Co. of Am., 148 F.2d 416, 428 (2d Cir. 1945).
139 Brown Shoe Co. v. United States, 370 U.S. 294, 344 (1962).
140 E.g., United States v. Topco Assocs., Inc., 405 U.S. 596 (1972) (joint venture involving territorial restraints);
Albrecht v. Herald Co., 390 U.S. 145 (1968) (maximum resale price maintenance); United States v. Arnold, Schwinn &
Co., 388 U.S. 365 (1967) (vertical territorial restraints).
141 E.g., Brown Shoe Co., 370 U.S. at 332-34.
142 E.g., United States v. Von’s Grocery Co., 384 U.S. 270 (1966) (blocking a merger that would have resulted in the
merged firm occupying a 7.5 percent market share in an unconcentrated market).
143 See, e.g., Joshua D. Wright & Douglas H. Ginsburg, The Goals of Antitrust: Welfare Trumps Choice, 81 FORDHAM
L. REV. 2405, 2405-06 (2013).
144 Since the 1970s, the Supreme Court has repeatedly described the antitrust laws as being principally concerned with
the protection of consumers. See NCAA v. Alston, 141 S. Ct. 2141, 2151 (2021); Ohio v. Am. Express Co., 138 S. Ct.
2274, 2284 (2018); Leegin Creative Leather Prods., Inc. v. PSKS, Inc., 551 U.S. 877, 886 (2007); Weyerhaeuser Co. v.
Ross-Simmons Hardwood Lumber Co., 549 U.S. 312, 324 (2007); Brooke Grp. Ltd. v. Brown & Williamson Tobacco
Corp., 509 U.S. 209, 224 (1993); Jefferson Par. Hosp. Dist. No. 2 v. Hyde, 466 U.S. 2, 15 (1984); NCAA v. Bd. of
Regents of Univ. of Okla., 468 U.S. 85, 107 (1984); Reiter v. Sonotone Corp., 442 U.S. 330, 343 (1979); see also John
B. Kirkwood & Robert H. Lande, The Fundamental Goal of Antitrust: Protecting Consumers, Not Increasing
Efficiency, 84 NOTRE DAME L. REV. 191, 219-24 (2008) (collecting lower court cases embracing the consumer-welfare
standard); ANTITRUST MODERNIZATION COMM’N, REPORT AND RECOMMENDATIONS 35 (Apr. 2007) (“For the last few
decades courts, agencies, and antitrust practitioners have recognized consumer welfare as the unifying goal of antitrust
law.”).
145 There are several issues here. First, Robert Bork used the term “consumer welfare” to refer to a total-welfare
standard that allows producer gains to offset consumer losses, while many commentators instead use the term
“consumer welfare” to mean consumer surplus. See, e.g., Barak Y. Orbach, The Antitrust Consumer Welfare Paradox,
7 J. COMPETITION L. & ECON. 133, 142-49 (2010). Both versions of the “consumer welfare” standard have supporters.
See Roger D. Blair & D. Daniel Sokol, Welfare Standards in U.S. and E.U. Antitrust Enforcement, 81 FORDHAM L.
REV. 2497 (2013) (favoring a total-welfare standard); Steven C. Salop, Question: What Is the Real and Proper Antitrust
Welfare Standard? Answer: The True Consumer Welfare Standard, 22 LOY. CONSUMER L. REV. 336 (2010) (favoring a
consumer-surplus standard). Second, the extent to which the consumer-welfare standard recognizes harms that sellers
suffer from anticompetitive conduct remains the subject of ongoing discussion. See, e.g., Herbert J. Hovenkamp, Is
Antitrust’s Consumer Welfare Principle Imperiled?, 45 J. CORP. L. 101, 113-15 (2019); C. Scott Hemphill & Nancy L.
Rose, Mergers That Harm Sellers, 127 YALE L.J. 2078 (2018). Third, some commentators have argued that the
consumer-welfare standard does not represent an accurate description of current antitrust doctrine for other reasons.
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Since the consumer-welfare revolution, courts have pared back some of the more interventionist
elements of mid-century antitrust. For example, the Supreme Court has overturned several
decisions establishing per se Section 1 liability for certain categories of conduct146 and
established restrictive standards for various types of monopolization claims.147 In a similar vein,
lower courts and the antitrust agencies have de-emphasized structural merger analysis in favor of
more detailed inquiries into the competitive effects of individual transactions.148
These shifts have generated controversy.149 The chair of the FTC and the Assistant Attorney
General for the DOJ’s Antitrust Division have both criticized the consumer-welfare standard and
advocated replacing it with a focus on the “competitive process.”150 In academic work, the FTC’s
chair has specifically emphasized the consumer-welfare standard’s alleged shortcomings with
respect to large technology platforms.151 Other commentators have criticized several applications
of the consumer-welfare standard as unduly permissive, but have defended the standard itself.152
These issues are discussed in greater detail later in this report.153
The Big Tech Firms: A Summary of Selected
Antitrust Allegations
The Big Tech firms have achieved tremendous financial success. As of the publication of this
report, the combined market capitalization of Meta, Alphabet (Google’s parent), Amazon, and
Apple is more than $5 trillion—a figure that exceeds the value of most national equity markets.154

E.g., Gregory J. Werden, Antitrust’s Rule of Reason: Only Competition Matters, 79 ANTITRUST L.J. 713, 713, 743
(2014) (arguing that “the rule of reason focuses solely on how a challenged restraint affects the competitive process,”
and that antitrust protects consumer welfare by protecting the “competitive process”); see also DEVLIN, supra note 10,
at 254-68 (contending that the consumer-welfare standard is descriptively inaccurate in several respects).
146 Leegin, 551 U.S. 877 (minimum resale price maintenance); State Oil Co. v. Khan, 522 U.S. 3 (1997) (maximum
resale price maintenance); Cont’l T.V., Inc. v. GTE Sylvania Inc., 433 U.S. 36 (1977) (vertical territorial restraints).
147 Pac. Bell Tel. Co. v. linkLine Commc’ns, Inc., 555 U.S. 438 (2009) (price squeezes); Weyerhaeuser, 549 U.S. 312
(predatory buying); Verizon Commc’ns Inc. v. L. Offs. of Curtis V. Trinko, LLP, 540 U.S. 398 (2004) (refusals to
deal); Brooke Grp., 509 U.S. 209 (predatory pricing).
148 See, e.g., United States v. Baker Hughes, Inc., 908 F.2d 981 (D.C. Cir. 1990); HORIZONTAL MERGER GUIDELINES,
supra note 100, at § 5.3.
149 For a collection of essays—many of them critical—on various aspects of these changes in antitrust theory and
doctrine, see HOW THE CHICAGO SCHOOL OVERSHOT THE MARK: THE EFFECT OF CONSERVATIVE ECONOMIC ANALYSIS
ON U.S. ANTITRUST (Robert Pitofsky ed. 2008). For a sympathetic account, see Elyse Dorsey, et al., Consumer Welfare
& the Rule of Law: The Case Against the New Populist Antitrust Movement, 47 PEPPERDINE L. REV. 861 (2020).
150 Khan, Amazon’s Antitrust Paradox, supra note 57, at 744-46; Assistant Att’y Gen. Jonathan Kanter Delivers
Remarks at New York City Bar Association’s Milton Handler Lecture (May 18, 2022),
https://www.justice.gov/opa/speech/assistant-attorney-general-jonathan-kanter-delivers-remarks-new-york-city-bar-
association.
151 Khan, Amazon’s Antitrust Paradox, supra note 57, at 716-17.
152 See, e.g., The Consumer Welfare Standard in Antitrust: Outdated or a Harbor in a Sea of Doubt?: Hearing Before
the Subcomm. on Antitrust, Competition & Consumer Rights of the S. Comm. on the Judiciary, (2017) (testimony of
Diana Moss, President, Am. Antitrust Inst.), https://www.judiciary.senate.gov/imo/media/doc/12-13-
17%20Moss%20Testimony.pdf [hereinafter “Moss Testimony”]; id. (statement of Carl Shapiro, Professor, Haas School
of Business at Univ. of Cal. at Berkeley), https://www.judiciary.senate.gov/imo/media/doc/12-13-
17%20Shapiro%20Testimony.pdf [hereinafter “Shapiro Testimony”].
153 See infra “Substantive Antitrust Doctrine.”
154 See Largest Companies by Market Cap, COMPANIESMARKETCAP (last visited Mar. 15, 2023),
https://companiesmarketcap.com/; Largest Stock Exchange Operators Worldwide as of October 2022, By Market
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While some have emphasized the quality of the firms’ offerings as the primary driver of their
ascent,155 others have alleged that Big Tech has obtained and cemented monopoly power through
anticompetitive conduct.156
This section of the report reviews selected antitrust allegations against the Big Tech firms.
Meta Platforms
Meta describes itself as a company that builds technology that “helps people connect, find
communities, and grow businesses.”157 More specifically, Meta offers a “family of apps” related
to social networking and messaging.158 This family of apps consists of:
 Facebook (a social network);
 Instagram (a photo-sharing platform);
 Messenger (a messaging app for Facebook users); and
 WhatsApp (a messaging app).159
In October 2022, Meta reported that Facebook had 1.98 billion daily active users and 2.96 billion
monthly active users.160 The company’s family of apps reportedly features 2.93 billion daily
active people and 3.71 billion monthly active people.161
Allegations of Market Power
Some observers have argued that Meta possesses significant market power in the market for
social networking.162 The Federal Trade Commission (FTC) shares that view. In an ongoing
monopolization lawsuit, the Commission has alleged that Meta has held monopoly power in the
market for “personal social networking services” (PSNS) since at least 2011.163 To support such

Capitalization of Listed Companies, STATISTA (Jan. 2023), https://www.statista.com/statistics/270126/largest-stock-
exchange-operators-by-market-capitalization-of-listed-companies/; Market Capitalization of Listed Domestic
Companies, THE WORLD BANK (last visited Mar. 15, 2023), https://data.worldbank.org/indicator/CM.MKT.LCAP.CD.
155 E.g., Investigation into the State of Competition in Digital Markets, Subcomm. on Antitrust, Commercial, & Admin.
L. of H. Comm. on the Judiciary (May 11, 2020) (statement of Randal C. Picker, James Parker Distinguished Service
Prof. of Law, The Univ. of Chi. L. Sch. at 34), https://picker.uchicago.edu/PickerHouseStatement.100.pdf.
156 E.g., HJC REPORT, supra note 11, at 12-17.
157 Meta Platforms, Inc., Annual Report (Form 10-K) at 7 (Feb. 3, 2022).
158 Id. Meta also produces augmented and virtual reality products via its Reality Labs division. See Eric Rosenbaum,
Why Reality Labs Will Keep Spending Billions Even as Meta Makes the Biggest Cuts in Its History, CNBC (Nov. 17,
2022), https://www.cnbc.com/2022/11/17/why-reality-labs-will-keep-losing-billions-even-as-meta-makes-big-
cuts.html.
159 Meta Platforms, Inc., Annual Report at 7.
160 Meta Platforms, Inc., Quarterly Report (Form 10-Q) at 33 (Oct. 27, 2022).
161 Id.
162 HJC REPORT, supra note 11, at 133; ONLINE PLATFORMS AND DIGITAL ADVERTISING: MARKET STUDY FINAL REPORT,
U.K. COMPETITION & MKTS AUTHORITY 146 (July 1, 2020),
https://assets.publishing.service.gov.uk/media/5fa557668fa8f5788db46efc/Final_report_Digital_ALT_TEXT.pdf
[hereinafter “CMA REPORT”]; Fiona M. Scott Morton & David C. Dinielli, Roadmap for an Antitrust Case Against
Facebook, OMIDYAR NETWORK 11-15 (June 2020), https://www.omidyar.com/wp-content/uploads/2020/06/Roadmap-
for-an-Antitrust-Case-Against-Facebook.pdf; DIGITAL PLATFORMS INQUIRY: FINAL REPORT, AUSTRALIAN COMPETITION
& CONSUMER COMM’N 9 (June 2019), https://www.accc.gov.au/system/files/Digital%20platforms%20inquiry%20-
%20final%20report.pdf [hereinafter “ACCC REPORT”].
163 Substitute Amended Complaint for Injunctive and Other Equitable Relief ¶ 164, FTC v. Facebook, Inc., No.
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claims, Meta’s critics have argued that the firm has persistently maintained a large market share
and benefited from substantial entry barriers, including powerful network effects and high
switching costs.164
Others disagree. Meta has argued that it operates in a “dynamic, intensely competitive” industry
in which there are many substitutes for its services.165 In its litigation with the FTC, the firm has
criticized the Commission’s alleged PSNS market as unduly narrow insofar as it excludes rivals
like YouTube, TikTok, LinkedIn, and Twitter.166
Meta and some commentators have also rejected the notion that entry barriers have caused the
market to decisively tip in Meta’s favor.167 For example, observers have highlighted the ability of
differentiated firms like TikTok and Snapchat to rapidly gain scale despite Meta’s ostensible
network advantages.168
Allegations of Anticompetitive Conduct
In addition to facing allegations of monopoly power, Meta has been accused of engaging in
anticompetitive conduct. The FTC’s lawsuit contends that Meta has maintained its dominant
position through its 2012 acquisition of Instagram and its 2014 acquisition of WhatsApp.169 The
Commission argues that Meta’s Instagram purchase allowed it to neutralize a rapidly growing
competitive threat, giving the firm control over what became two of the most popular social
networks in the world.170 Similarly, the FTC contends that Meta’s acquisition of WhatsApp
preserved its monopoly by preventing WhatsApp from entering the PSNS market.171
Besides targeting Meta’s major acquisitions, the FTC and some commentators have criticized the
company’s treatment of software developers.172 These allegations involve access to Facebook
Platform—an initiative whereby Meta encouraged developers to create apps that interoperate with
Facebook.173 As part of this initiative, Meta provided software developers with application
programming interfaces (APIs) and other tools that allowed them to access certain Facebook data

1:20-cv-03590 (D.D.C. Sept. 8, 2021).
164 Id. ¶ 212; HJC REPORT, supra note 11, at 136-47; Scott Morton & Dinielli, supra note 162, at 11; ACCC REPORT,
supra note 162, at 58. The FTC and some commentators have also attempted to establish that Meta has monopoly
power with direct evidence, arguing that the firm has degraded the quality of its products without losing significant
numbers of users. Substitute Amended Complaint ¶¶ 205-09, FTC v. Facebook, Inc., No. 1:20-cv-03590 (D.D.C. Sept.
8, 2021); Dina Srinivasan, The Antitrust Case Against Facebook: A Monopolist’s Journey Towards Pervasive
Surveillance in Spite of Consumer’s Preference for Privacy, 16 BERKELEY BUS. L.J. 39 (2019).
165 Memorandum in Support of Facebook, Inc.’s Motion to Dismiss FTC’s Complaint at 11, FTC v. Facebook, Inc., No.
1:20-cv-03590 (D.D.C. Mar. 10, 2021).
166 Memorandum in Support of Facebook, Inc.’s Motion to Dismiss FTC’s Complaint at 10, FTC v. Facebook, Inc., No.
1:20-cv-03590 (D.D.C. Oct. 4, 2021).
167 Id. at 13-16; Herbert J. Hovenkamp, Selling Antitrust, 73 HASTINGS L.J. 1621, 1623 (2022) [hereinafter
“Hovenkamp, Selling Antitrust”]; Jay Ezrielev & Genaro Marquez, Interoperability: The Wrong Prescription for
Platform Competition, COMPETITION POLICY INT’L ANTITRUST CHRON. 8, 13-14 (June 2021).
168 Hovenkamp, Selling Antitrust, supra note 167, at 1623; Ezrielev & Marquez, supra note 167, at 8.
169 Substitute Amended Complaint ¶¶ 77-129, FTC v. Facebook, Inc., No. 1:20-cv-03590 (D.D.C. Sept. 8, 2021); see
also HJC REPORT, supra note 11, at 150-60 (arguing that Meta’s Instagram and WhatsApp acquisitions harmed
competition).
170 Substitute Amended Complaint ¶¶ 80-106, FTC v. Facebook, Inc., No. 1:20-cv-03590 (D.D.C. Sept. 8, 2021).
171 Id. ¶¶ 107-29.
172 Id. ¶¶ 130-163; HJC REPORT, supra note 11, at 166-70; Scott Morton & Dinielli, supra note 162, at 24-25.
173 Substitute Amended Complaint ¶¶ 25-42, FTC v. Facebook, Inc., No. 1:20-cv-03590 (D.D.C. Sept. 8, 2021).
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and functionalities.174 According to the FTC, Facebook Platform ultimately became key
infrastructure for app developers because of Facebook’s large user base.175
The Commission’s lawsuit alleges that Meta used its control over this key infrastructure to
preserve its social networking monopoly. In particular, the FTC claims that Meta required
developers that participated in Facebook Platform to refrain from creating apps that would
compete with Facebook products.176 In doing so, Meta allegedly suppressed potential competitive
threats.177
Meta has denied engaging in anticompetitive conduct. The company has argued that its Instagram
acquisition was procompetitive because the transaction allowed Meta to invest significant
resources and expertise in developing Instagram, thereby hastening the small firm’s growth.178
Meta has also defended its WhatsApp purchase, arguing that the FTC has failed to present
evidence that WhatsApp would have likely entered social networking absent the acquisition.179
Finally, Meta has argued that its policies governing access to Facebook Platform—which it has
since revised—were lawful under duty-to-deal doctrine.180
As of the publication of this report, the FTC’s monopolization case against Meta is in discovery, a
pre-trial stage of litigation in which the parties develop evidence that can be used at trial.
Although the district court rejected the agency’s initial complaint for failing to plausibly allege
monopoly power,181 the court ultimately allowed the case to proceed after concluding that the
Commission’s amended complaint was sufficiently plausible to survive a motion to dismiss.182
Google
Google is a ubiquitous presence in the digital economy. The firm began as an internet search
company, and is now also a major player in digital advertising, mobile operating systems, app
distribution, digital maps, email, and web browsing.183 The following subsections discuss antitrust
allegations involving Google’s conduct related to online search, mobile operating systems and
app distribution, and digital advertising.

174 Id.
175 Id. ¶ 131.
176 Id. ¶ 133.
177 Id. ¶ 134.
178 Memorandum in Support of Facebook, Inc.’s Motion to Dismiss FTC’s Complaint at 29-30, FTC v. Facebook, Inc.,
No. 1:20-cv-03590 (D.D.C. Oct. 4, 2021).
179 Id. at 24.
180 Id. at 35.
181 FTC v. Facebook, Inc., 560 F. Supp. 3d 1, 4 (D.D.C. 2021).
182 FTC v. Facebook, Inc., 581 F. Supp. 3d 34, 43-52 (D.D.C. 2022). While the district court has allowed the FTC’s
challenge to Meta’s Instagram and WhatsApp acquisitions to proceed, it has rejected the agency’s claims involving
access to Facebook Platform. Id. at 57-59. In rejecting the latter claims, the court concluded that Meta had no general
duty to allow potential rivals to access Facebook Platform. Id. at 58-59. Although the court indicated that specific
refusals may be actionable, it held that the refusals alleged by the FTC could not justify injunctive relief because they
occurred in 2013 and were not ongoing. Id.
183 HJC REPORT, supra note 11, at 174.
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Online Search
Allegations of Market Power
Some commentators have argued that Google has significant market power in the market for
general online search.184 The DOJ agrees. In a pending monopolization lawsuit, the DOJ contends
that Google has monopoly power in the market for “general search services” based on an alleged
market share of 88 percent and the presence of substantial entry barriers, including economies of
scale.185
For its part, Google has claimed that it operates in a “highly competitive environment” and faces
a “vast array of competitors.”186 The company also argues that, for particular search queries, it
competes against a range of firms—such as Amazon, eBay, and Yelp—that would not fall within
a market for general search services.187
Allegations of Anticompetitive Conduct
Search Distribution
The DOJ’s monopolization lawsuit contends that Google has maintained its search monopoly
through various exclusionary agreements with firms that control search distribution.188 In
particular, the DOJ alleges that Google pays mobile device manufacturers, wireless carriers, and
browser developers to secure default status for its general search engine.189 Additionally, the
company—which also controls the Android mobile operating system—allegedly conditions the
availability of some “must-have” Google apps and APIs for Android devices on manufacturers’
agreements to preinstall certain apps that use Google Search as their default search engine.190
Through such agreements and its control of the Chrome browser, the DOJ argues, Google
“effectively owns or controls search distribution channels accounting for roughly 80 percent of
general search queries in the United States.”191 By locking up these distribution channels, Google
has allegedly prevented rivals from gaining the scale necessary to serve as effective
competitors.192

184 CMA REPORT, supra note 162, at 73; HJC REPORT, supra note 11, at 176-82; ACCC REPORT, supra note 162, at 58;
Google Search (Shopping) (Case AT.39740), Commission Decision ¶ 271 (June 27, 2017),
https://ec.europa.eu/competition/antitrust/cases/dec_docs/39740/39740_14996_3.pdf [hereinafter “EC Google
Shopping Decision”].
185 Amended Complaint ¶¶ 92-96, United States v. Google LLC, No. 1:20-cv-03010 (D.D.C. Jan. 15, 2021).
186 HJC REPORT, supra note 11, at 179.
187 Id.
188 Amended Complaint ¶ 4, United States v. Google LLC, No. 1:20-cv-03010 (D.D.C. Jan. 15, 2021). A group of state
attorneys general has also brought a similar monopolization case challenging Google’s conduct in search markets.
Complaint, State of Colorado, et al. v. Google, LLC, No. 1:20-cv-03715 (D.D.C. Dec. 17, 2020).
189 Amended Complaint ¶ 4, United States v. Google LLC, No. 1:20-cv-03010 (D.D.C. Jan. 15, 2021).
190 Id. ¶¶ 72-77.
191 Id. ¶ 5.
192 Id. ¶ 8. In July 2018, the European Commission fined Google €4.34 billion for requiring device manufacturers to
pre-install the Google Search app and Chrome browser as a condition of licensing the Google Play app store; paying
device manufacturers and mobile network operators to exclusively pre-install the Google Search app on their devices;
and preventing device manufacturers that pre-install certain Google apps from selling devices that run versions of
Android that Google had not approved. See Press Release, Euro. Comm’n, Antitrust: Commission Fines Google €4.34
Billion for Illegal Practices Regarding Android Mobile Devices to Strengthen Dominance of Google’s Search Engine
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Google has denied the DOJ’s allegations. The company argues that its agreements with browser
developers do not preclude developers from integrating or promoting other search engines.193
Google also contends that, even if the agreements required exclusivity, they are the result of
lawful, customer-instigated “competition for the contract” that the firm has won because of the
superiority of its search engine.194
Similarly, Google has argued that its agreements with mobile device manufacturers and wireless
carriers do not preclude its counterparties from preinstalling rival apps.195 The company also
claims that the agreements would not result in substantial foreclosure of search distribution
channels even if they did require exclusivity.196
As of the publication of this report, Google’s motion for summary judgment is pending before the
district court.197
Self-Preferencing
Commentators and some foreign regulators have also argued that Google has leveraged its
dominance in general search to favor its own vertical offerings. For example, the HJC Report
concluded that Google has adjusted its search algorithms to automatically elevate some of
Google’s vertical services, like its video-sharing platform YouTube, in search results.198
This type of self-preferencing prompted the European Commission—which enforces European
Union competition law—to fine Google €2.42 billion in 2017 for giving prominent placement to
its comparison-shopping service and demoting rival services in search results.199
The FTC investigated similar allegations of self-preferencing involving Google Search in 2012,
but concluded that it had not found sufficient evidence of an antitrust violation.200 The agency
determined that Google’s favorable placement of its own verticals could plausibly be viewed as
an improvement in the quality of Google’s search product.201 The Commission also did not find
sufficient evidence that Google had manipulated its search algorithms to unfairly disadvantage
rival vertical websites.202

(July 18, 2018), https://ec.europa.eu/commission/presscorner/detail/en/IP_18_4581 [hereinafter “EC Android Case”].
193 Defendant’s Memorandum of Points and Authorities in Support of its Motion for Summary Judgment at 28-31,
United States v. Google LLC, No. 1:20-cv-03010 (D.D.C. Jan. 11, 2023).
194 Id. at 35-38.
195 Id. at 39-40.
196 Id. at 40-41.
197 Dave Simpson, Google Seeks Win in Default Search Engine Antitrust Suits, LAW360 (Jan. 11, 2023),
https://www.law360.com/articles/1564958.
198 HJC REPORT, supra note 11, at 187-92.
199 EC Google Shopping Decision, supra note 184.
200 Statement of the Federal Trade Commission Regarding Google’s Search Practices, In the Matter of Google Inc., No.
111-0163 (FTC Jan. 3, 2013).
201 Id. at 3.
202 Id.
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Mobile Operating Systems and App Distribution
Allegations of Market Power
Mobile Operating Systems
In addition to operating a major search engine, Google controls Android—a leading mobile
operating system. Android and Apple’s iOS represent the two dominant mobile operating
systems, together accounting for 99 percent of the market.203 Because Apple does not license iOS
to other device manufacturers, Android by itself occupies a very large share of the market for
licensable mobile operating systems—by some estimates, 99 percent of that market.204
Some commentators have argued that the market for licensable mobile operating systems is the
relevant one for antitrust purposes, based on factors like high switching costs.205 Private plaintiffs
and (in a separate case) a group of state attorneys general have argued that Google has monopoly
power in this market based on the company’s dominant market share and the presence of
substantial entry barriers, such as network effects and research and development costs.206
Google denies such allegations, arguing that consumers “can and do switch and multi-home
among and between mobile and nonmobile ecosystems, including between Android and iOS.”207
Mobile App Distribution
Litigants have also contended that, through its Google Play Store, Google has market power in
certain markets related to mobile-app distribution. Some plaintiffs have defined the relevant
antitrust market as consisting of the distribution of apps to Android users.208 They allege that
Google has monopoly power in this market based on the Play Store’s market share of more than
90 percent, strong network effects, high switching costs, and Google’s ability to charge a 30
percent commission on apps purchased through the Play Store.209
Some plaintiffs have also argued in the alternative that Google has market power in a broader
market for mobile app distribution—that is, a market not limited to Android users.210 A group of

203 HJC REPORT, supra note 11, at 100-02.
204 First Amended Complaint ¶ 7, State of Utah et al. v. Google LLC, No. 3:21-cv-05227 (N.D. Cal. Nov. 1, 2021); see
also Second Amended Complaint for Injunctive Relief ¶¶ 16, 55, Epic Games, Inc. v. Google LLC, No. 3:20-cv-05671
(N.D. Cal. Nov. 17, 2022) (alleging a market share of “over 95%”).
205 HJC REPORT, supra note 11, at 102. In a 2018 enforcement action, the European Commission concluded that
competition from Apple does not sufficiently constrain Google for similar reasons. EC Android Case, supra note 192.
206 Second Amended Complaint for Injunctive Relief ¶¶ 55-64, Epic Games, Inc. v. Google LLC, No. 3:20-cv-05671
(N.D. Cal. Nov. 17, 2022); First Amended Complaint ¶¶ 44-58, State of Utah et al. v. Google LLC, No. 3:21-cv-05227
(N.D. Cal. Nov. 1, 2021).
207 Defendants’ Answers and Defenses to State of Utah et al. First Amended Complaint ¶ 55-56, No. 3:21-cv-05227
(N.D. Cal. Nov. 15, 2021); see also Defendants’ Answer, Defenses, and Counterclaims to Epic Games, Inc.’s Second
Amended Complaint for Injunctive Relief ¶¶ 55, 57, No. 3:20-cv-05671 (N.D. Cal. Dec. 1, 2022).
208 Second Amended Complaint for Injunctive Relief ¶¶ 68-72, Epic Games, Inc. v. Google LLC, No. 3:20-cv-05671
(N.D. Cal. Nov. 17, 2022); First Amended Complaint ¶¶ 63-73, State of Utah et al. v. Google LLC, No. 3:21-cv-05227
(N.D. Cal. Nov. 1, 2021).
209 Second Amended Complaint for Injunctive Relief ¶¶ 75-88, Epic Games, Inc. v. Google LLC, No. 3:20-cv-05671
(N.D. Cal. Nov. 17, 2022); First Amended Complaint ¶¶ 76-78, State of Utah et al. v. Google LLC, No. 3:21-cv-05227
(N.D. Cal. Nov. 1, 2021).
210 Second Amended Complaint for Injunctive Relief ¶ 73, Epic Games, Inc. v. Google LLC, No. 3:20-cv-05671
(N.D. Cal. Nov. 17, 2022); First Amended Complaint ¶¶ 79-81, State of Utah et al. v. Google LLC, No. 3:21-cv-05227
(N.D. Cal. Nov. 1, 2021).
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state attorneys general, for example, has argued that Google occupies a sizeable share of this
market, enjoys large profit margins, and benefits from formidable entry barriers.211
Google rejects these claims. It contends that consumers can use different platforms to access apps
and that “Apple and Google compete vigorously in the mobile operating system environment on
multiple dimensions, including innovation, price, privacy, and security.”212
In-App Payment Processing
Plaintiffs have further claimed that Google has monopoly power in a market for in-app payment
(IAP) processing for Android apps.213 They have based this claim on the Google Play Store’s
large share of the market for Android app distribution and Google’s requirement that software
developers using the Play Store also use Google’s IAP processor.214
As discussed, for many transactions, Google charges a 30 percent commission for IAP
processing—a rate that is considerably higher than those charged by other electronic payment
processors.215
Google has denied possessing monopoly power related to IAP processing.216
Allegations of Anticompetitive Conduct
Mobile App Distribution
Google has also been accused of engaging in a variety of anticompetitive activities involving app
distribution.
First, Google has allegedly imposed technical barriers that make it difficult for consumers to
download Android apps from sources other than the Google Play Store—a practice commonly
known as “sideloading.”217 In particular, litigants have claimed that sideloading Android apps

211 First Amended Complaint ¶¶ 79-81, State of Utah et al. v. Google LLC, No. 3:21-cv-05227 (N.D. Cal. Nov. 1,
2021). The state attorneys general allege that Google’s share of this market in the United States exceeds 30 percent,
while its share of the global market (excluding China) is approximately 53 percent by revenue. Id. ¶ 80.
212 Defendants’ Answers, Defenses, and Counterclaims to Epic Games, Inc.’s Second Amended Complaint for
Injunctive Relief ¶ 80, No. 3:20-cv-05671 (N.D. Cal. Dec. 1, 2022).
213 Second Amended Complaint for Injunctive Relief ¶¶ 158-60, Epic Games, Inc. v. Google LLC, No. 3:20-cv-05671
(N.D. Cal. Nov. 17, 2022); First Amended Complaint ¶¶ 182-86, State of Utah et al. v. Google LLC, No. 3:21-cv-
05227 (N.D. Cal. Nov. 1, 2021).
214 Second Amended Complaint for Injunctive Relief ¶¶ 158-60, Epic Games, Inc. v. Google LLC, No. 3:20-cv-05671
(N.D. Cal. Nov. 17, 2022); First Amended Complaint ¶¶ 182-86, State of Utah et al. v. Google LLC, No. 3:21-cv-
05227 (N.D. Cal. Nov. 1, 2021).
215 Second Amended Complaint for Injunctive Relief ¶ 160, Epic Games, Inc. v. Google LLC, No. 3:20-cv-05671
(N.D. Cal. Nov. 17, 2022). In March 2021, Google announced plans to lower its commissions from 30 percent to 15
percent for the first $1 million in revenue that developers earn using Google’s billing system. Manish Singh, Google
Play Drops Commissions to 15% from 30%, Following Apple’s Move Last Year, TECHCRUNCH (Mar. 16, 2021),
https://techcrunch.com/2021/03/16/google-play-drops-commissions-to-15-from-30-following-apples-move-last-year/.
216 Defendants’ Answers, Defenses, and Counterclaims to Epic Games, Inc.’s Second Amended Complaint for
Injunctive Relief ¶ 158, No. 3:20-cv-05671 (N.D. Cal. Dec. 1, 2022); Defendants’ Answers and Defenses to State of
Utah et al. First Amended Complaint ¶ 182, No. 3:21-cv-05227 (N.D. Cal. Nov. 15, 2021).
217 First Amended Complaint ¶¶ 83-95, State of Utah et al. v. Google LLC, No. 3:21-cv-05227 (N.D. Cal. Nov. 1,
2021).
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entails a complicated process that includes several security warnings discouraging such actions.218
Google has also been accused of making it unnecessarily difficult to update sideloaded apps.219
Second, Google has allegedly barred software developers from distributing competing app stores
through the Google Play Store.220
Third, Google has allegedly required mobile device manufacturers that license Android and
certain other key Google services to preinstall the Google Play Store on their devices.221 Plaintiffs
have argued that this preinstallation requirement harms competition by giving the Play Store an
advantage over other app stores.222
Fourth, Google has allegedly required device manufacturers that offer the Google Play Store and
other “must-have” Google services to refrain from selling devices that run “Android forks”—
modified versions of Android that Google has not approved.223 Plaintiffs argue that these
restrictions have stifled the development of alternative versions of Android that would be free
from some of the restrictions on app distribution discussed above.224
Fifth, Google has allegedly entered into revenue-sharing agreements that deter device
manufacturers from developing competing app stores.225 In particular, the challenged agreements
give device manufacturers a share of Google’s advertising and Play Store revenue from the
devices they sell in exchange for a commitment to refrain from competing against the Play
Store.226
Google has either denied engaging in the relevant conduct or rejected the contention that such
conduct is anticompetitive.227
In-App Payment Processing
Plaintiffs have also accused Google of engaging in anticompetitive conduct in the market for
Android IAP processing. They have alleged that Google’s requirement that developers using the
Play Store also use Google’s IAP processor represents an unlawful tying arrangement.228

218 Id.
219 Id. ¶ 96.
220 Id. ¶¶ 107-10.
221 Id. ¶¶ 124-25.
222 Id. ¶ 125.
223 Id. ¶¶ 105-06.
224 Id.
225 Id. ¶¶ 130-35.
226 Id.
227 Defendants’ Answers and Defenses to State of Utah et al. First Amended Complaint ¶¶ 83-89, 96, 105-110, 124-25,
130-35, No. 3:21-cv-05227 (N.D. Cal. Nov. 15, 2021).
228 Second Amended Complaint for Injunctive Relief ¶¶ 161-66, Epic Games, Inc. v. Google LLC, No. 3:20-cv-05671
(N.D. Cal. Nov. 17, 2022); First Amended Complaint ¶¶ 162-67, State of Utah et al. v. Google LLC, No. 3:21-cv-
05227 (N.D. Cal. Nov. 1, 2021).
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Digital Advertising
Allegations of Market Power
In addition to its search and app-distribution activities, Google is a major force in digital display
advertising markets.
In those markets, online ad publishers—like news websites—sell advertising space through
exchanges.229 Those ad exchanges conduct automated auctions in which advertisers can bid for ad
space.230
Intermediaries facilitate this process for both publishers and advertisers. Large publishers manage
their ad inventory using a type of software known as an ad server, which interfaces with ad
exchanges on behalf of publishers.231 On the other side of the market, advertisers employ
ad-buying tools, which connect them with ad exchanges and allow them to purchase ad space.232
Google operates in several segments of these markets via an ad exchange, a publisher ad server,
and ad-buying tools for advertisers.233
The DOJ and (in a separate lawsuit) a group of state attorneys general (state AGs) have argued
that Google has monopoly power in multiple ad-tech markets.
In January 2023, the DOJ filed a complaint alleging that Google has monopoly power in the
markets for publisher ad servers,234 ad exchanges,235 and advertiser ad networks.236
In a separate case, a group of state AGs has alleged that Google has monopoly power in the
markets for ad exchanges, ad servers, and ad-buying tools for small advertisers.237 The state AGs
also contend that Google has monopoly power or a dangerous probability of acquiring monopoly
power in the market for ad-buying tools for large advertisers.238
In September 2022, a federal district court concluded that the state AGs’ allegations involving
monopoly power were sufficiently plausible to survive a motion to dismiss.239

229 Opinion and Order at 3, In re Google Digital Advertising Antitrust Litigation, No. 21-md-3010 (S.D.N.Y. Sept. 13,
2022).
230 Id.
231 Id. at 4.
232 Id. at 10-11.
233 Id. at 6-12.
234 Complaint ¶ 285, United States v. Google LLC, No. 1:23-cv-00108 (E.D. Va. Jan. 24, 2023).
235 Id. ¶ 296.
236 Id. ¶ 301.
237 Opinion and Order at 7-8, 11, In re Google Digital Advertising Antitrust Litigation, No. 21-md-3010 (S.D.N.Y.
Sept. 13, 2022).
238 Id. at 11.
239 Id. at 19, 34-35. Google has denied possessing monopoly power in the ad-exchange market, but its motion to
dismiss did not challenge the other allegations of monopoly power. Id. at 5-6. In response to the DOJ’s lawsuit, Google
published a blog post in which it argued that competition in online ad markets is “increasing,” citing the growing ad
businesses of Microsoft, Amazon, Apple, TikTok, and several specialized ad-tech companies. Dan Taylor, DOJ’s
Lawsuit Ignores the Enormous Competition in the Online Advertising Industry, GOOGLE (Jan. 24, 2023),
https://blog.google/outreach-initiatives/public-policy/doj-ad-tech-lawsuit-response/.
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Allegations of Anticompetitive Conduct
The DOJ and state AG lawsuits contend that Google has engaged in a range of anticompetitive
practices in several digital-advertising markets, allowing it to obtain and cement a dominant
position across the ad-tech stack.
The DOJ’s lawsuit claims that, in the early 2000s, Google’s ad-buying tools occupied a dominant
position on the advertiser side of the ad-tech market.240 Then, in 2008, Google acquired a firm
called DoubleClick, which operated a leading publisher ad server and a nascent ad exchange.241
After the DoubleClick acquisition, the DOJ contends, Google leveraged its position across the
ad-tech chain to benefit its own properties. Among other things, the DOJ alleges that Google
made demand from its ad-buying tools available only through its ad exchange.242 Google also
allegedly required publishers to use its ad server to receive real-time bids from its ad exchange.243
The state AG ad-tech lawsuit makes similar allegations.244
In September 2022, a federal district court held that the state AGs had plausibly alleged tying
claims under Sections 1 and 2 of the Sherman Act based on their assertion that Google had
coerced publishers into using its ad server as a condition of receiving live bids from its ad
exchange.245
The DOJ and state AG lawsuits also target a program used by Google’s ad server that allegedly
gave Google’s ad exchange advantages over rival exchanges.246 Another set of accusations
involves programs under which Google allegedly manipulated bids from its advertiser clients in
ways that advantaged its ad exchange and publisher ad server.247
The September 2022 district court decision in the state AG lawsuit concluded that the allegations
of anticompetitive harm from these activities were sufficiently plausible to survive a motion to
dismiss.248
The Google ad-tech lawsuits are complex and a full discussion of the relevant claims is beyond
the scope of this report. Most of the allegations nevertheless implicate a recurring theme in

240 Complaint ¶¶ 11-13, United States v. Google LLC, No. 1:23-cv-00108 (E.D. Va. Jan. 24, 2023).
241 Id. ¶ 16. The FTC declined to challenge Google’s DoubleClick acquisition at the time. Press Release, Fed. Trade
Comn’n, Federal Trade Commission Closes Google/DoubleClick Investigation (Dec. 20, 2007),
https://www.ftc.gov/news-events/news/press-releases/2007/12/federal-trade-commission-closes-googledoubleclick-
investigation.
242 Complaint ¶ 89, United States v. Google LLC, No. 1:23-cv-00108 (E.D. Va. Jan. 24, 2023).
243 Id. ¶ 104. According to the DOJ’s complaint, publishers could use Google’s ad exchange without using its ad server
by selling ad space based on historical—rather than real-time—prices. Id. The DOJ contends, however, that this was
not an attractive option because the resulting prices were often considerably lower than those received from real-time
bids. Id.
244 Opinion and Order at 18, In re Google Digital Advertising Antitrust Litigation, No. 21-md-3010 (S.D.N.Y. Sept. 13,
2022).
245 Id. at 16-20, 77-78.
246 Complaint ¶¶ 21, 120-25, United States v. Google LLC, No. 1:23-cv-00108 (E.D. Va. Jan. 24, 2023); Opinion and
Order at 44-50, In re Google Digital Advertising Antitrust Litigation, No. 21-md-3010 (S.D.N.Y. Sept. 13, 2022).
247 Complaint ¶¶ 24, 139, 161-62, United States v. Google LLC, No. 1:23-cv-00108 (E.D. Va. Jan. 24, 2023); Opinion
and Order at 50-55, In re Google Digital Advertising Antitrust Litigation, No. 21-md-3010 (S.D.N.Y. Sept. 13, 2022).
248 Opinion and Order at 44-55, In re Google Digital Advertising Antitrust Litigation, No. 21-md-3010 (S.D.N.Y. Sept.
13, 2022).
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discussions of antitrust and Big Tech firms: the leveraging of economic power to obtain and
solidify dominance across different markets.249
Google maintains that its conduct is permissible under antitrust doctrine governing refusals to
deal, product design, and tying.250
Amazon
Like Google, Amazon has expanded its remit over time. The company began as an online
bookseller, but now operates a leading e-commerce marketplace, a major cloud-computing
platform, a logistics network, and a television and film studio.251 The discussion below focuses
principally on the company’s e-commerce activities.
Allegations of Market Power
The HJC Report concluded that Amazon “has significant and durable market power in the U.S.
online retail market.”252 While the report acknowledged a wide range of estimates of Amazon’s
share of that market, it determined that estimates “at about 50% or higher are more credible than
lower estimates of 30-40%.”253 The report also characterized Amazon as the “dominant online
marketplace,” noting that the firm reportedly controls “about 65% to 70% of all U.S. online
marketplace sales.”254
Based on interviews and other material, the report concluded that Amazon has monopoly power
over “most” third-party sellers on its e-commerce marketplace and “many” of its suppliers, in
addition to significant market power over consumers.255 Such power is unlikely to erode, the
report argued, because of network effects, switching costs, and the difficulty that rivals would
face in developing a comparable logistics network.256
The Attorney General for the District of Columbia (D.C. AG) made similar allegations in a 2021
lawsuit brought under District of Columbia law.257 The D.C. AG lawsuit claimed that Amazon
had monopoly power among online marketplaces based on an alleged market share of 50%-70%,
the company’s ability to dictate certain terms to third-party sellers, and entry barriers like network
effects, data advantages, and extensive logistics capabilities.258

249 See generally Patrick F. Todd, Digital Platforms and the Leverage Problem, 98 NEB. L. REV. 486 (2019).
250 Reply Memorandum of Law in Further Support of Google LLC’s Motion to Dismiss Counts I through IV of State
Plaintiffs’ Third Amended Complaint at 16-30, In re Google Digital Advertising Antitrust Litigation, No. 21-md-3010
(S.D.N.Y. May 5, 2022).
251 HJC REPORT, supra note 11, at 247.
252 Id. at 254.
253 Id.
254 Id. at 255.
255 Id. at 257, 259.
256 Id. at 260.
257 First Amended Complaint, District of Columbia v. Amazon.com, Inc., No. 2021-CA-001775 (D.C. Super. Ct. Sept.
10, 2021).
258 Id. ¶¶ 85-86. During an investigation that began in November 2020, the European Commission preliminarily
concluded that Amazon occupied a dominant position in certain European markets for the provision of online
marketplace services to third-party sellers. Press Release, Euro. Comm’n, Antitrust: Commission Accepts
Commitments by Amazon Barring it From Using Marketplace Seller Data, and Ensuring Equal Access to Buy Box and
Prime (Dec. 20, 2022), https://ec.europa.eu/commission/presscorner/detail/en/ip_22_7777 [hereinafter “Amazon EC
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Amazon rejected those allegations, arguing that it competes in a broader market that includes
physical retail stores.259
In 2022, the Superior Court of the District of Columbia dismissed the D.C. AG lawsuit on several
grounds, including a failure to plausibly allege monopoly power.260 The D.C. AG has appealed
that decision.261
Allegations of Anticompetitive Conduct
Most-Favored-Nation and Pricing-Parity Clauses
The D.C. AG lawsuit discussed above focused on most-favored-nation and pricing-parity clauses
in Amazon’s agreements with third-party sellers that use its e-commerce marketplace.262 One
iteration of these provisions—which Amazon has discontinued—prohibited third-party sellers
from offering their products elsewhere online at prices lower than those the sellers offered on
Amazon.263 Under a later version of the relevant policy, Amazon indicated that it may remove or
decline to feature products that third-party sellers offered on Amazon at prices significantly
higher than those the sellers recently charged in any venue.264
The D.C. AG argued that the latter policy was “effectively identical” to the earlier pricing-parity
provision because—in practice—Amazon continued to penalize third-party sellers for any offers
undercutting the sellers’ prices on Amazon.265 The HJC Report reached similar conclusions about
the relevant policies and contended that they harmed competition among e-commerce
marketplaces.266
In 2022, the Superior Court of the District of Columbia dismissed the D.C. AG’s allegations. The
court reasoned that the newer Amazon policy did not prohibit third-party sellers from offering
lower prices in other venues; that any broader implementation of the policy was not attributable
to the agreements themselves; and that the D.C. AG had not plausibly alleged monopoly power,

Commitments”].
259 Defendant Amazon.com, Inc.’s Opposed Motion to Dismiss Plaintiff District of Columbia’s Amended Complaint at
15-16, District of Columbia v. Amazon.com, Inc., No. 2021-CA-001775 (D.C. Super. Ct. Oct. 25, 2021); see also HJC
REPORT, supra note 11, at 255 (noting Amazon’s argument that its share of the total retail market is “the most
appropriate and relevant” method of estimating its market share).
260 Order at 15-16, District of Columbia v. Amazon.com, Inc., No. 2021-CA-001775 (D.C. Super. Ct. Aug. 1, 2022).
261 Notice of Appeal, District of Columbia v. Amazon.com, Inc., No. 2021-CA-001775 (D.C. Super. Ct. Aug. 25,
2022).
262 First Amended Complaint ¶¶ 5-10, District of Columbia v. Amazon.com, Inc., No. 2021-CA-001775 (D.C. Super.
Ct. Sept. 10, 2021). The Attorney General of California has filed a similar lawsuit under California unfair-competition
law. See Complaint, The People of the State of California v. Amazon.com, Inc., No. CGC-22-601826 (Cal. Super. Ct.
Sept. 15, 2022). For a discussion of the antitrust issues raised by most-favored-nation clauses in online platform
markets, see Jonathan B. Baker & Fiona Scott Morton, Antitrust Enforcement Against Platform MFNs, 127 YALE L.J.
2176 (2018).
263 First Amended Complaint ¶¶ 5-8, District of Columbia v. Amazon.com, Inc., No. 2021-CA-001775 (D.C. Super. Ct.
Sept. 10, 2021).
264 Order at 8, District of Columbia v. Amazon.com, Inc., No. 2021-CA-001775 (D.C. Super. Ct. Aug. 1, 2022).
265 First Amended Complaint ¶ 9, District of Columbia v. Amazon.com, Inc., No. 2021-CA-001775 (D.C. Super. Ct.
Sept. 10, 2021); see also Order at 8-9, District of Columbia v. Amazon.com, Inc., No. 2021-CA-001775 (D.C. Super.
Ct. Aug. 1, 2022).
266 HJC REPORT, supra note 11, at 295-97.
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meaning it could not prevail on a claim alleging unilateral anticompetitive conduct.267 As
discussed, the D.C. AG has appealed the Superior Court’s decision.268
Tying
The HJC Report and some foreign competition authorities have also taken issue with the link
between Amazon’s e-commerce marketplace and its logistics service, Fulfillment by Amazon
(FBA).269 According to the report, Amazon effectively requires third-party sellers to use FBA as a
condition of participating in Amazon Prime—a subscription service that offers customers fast
shipping of eligible products, among other benefits.270 Many third-party sellers also reported their
belief that Amazon favors sellers who use FBA in its product search results and in managing its
“Buy Box”—the program that determines which sellers “win” particular product sales.271 As a
result of these practices, the report contends, many third-party sellers regard use of FBA as
essential to success on Amazon’s marketplace.272
Amazon has responded that it provides non-discriminatory access to the Buy Box and that
participation in FBA is voluntary.273
Use of Third-Party Seller Data
Amazon’s dual role as both a marketplace operator and a seller on its own marketplace has also
attracted scrutiny. Critics have contended that this integration generates conflicts of interest,
which have led Amazon to leverage control of its marketplace to advantage its own products and
services in various ways.274
Some of these allegations involve Amazon’s use of data. The HJC Report and European
regulators have accused Amazon of using data generated by third-party sellers on its marketplace
to identify and imitate popular products for its private-label business.275

267 Order at 8-9, 15-16, District of Columbia v. Amazon.com, Inc., No. 2021-CA-001775 (D.C. Super. Ct. Aug. 1,
2022). The D.C. AG lawsuit also included allegations regarding Amazon’s contracts with suppliers, which are not
discussed here.
268 Notice of Appeal, District of Columbia v. Amazon.com, Inc., No. 2021-CA-001775 (D.C. Super. Ct. Aug. 25,
2022).
269 HJC REPORT, supra note 11, at 287-90; Amazon EC Commitments, supra note 258; Adam Satariano, Amazon is
Fined $1.3 Billion in Italy Over Antitrust Violations, N.Y. TIMES (Dec. 9, 2021),
https://www.nytimes.com/2021/12/09/business/amazon-italy-fine.html.
270 HJC REPORT, supra note 11, at 287. While there is a way third-party sellers can become eligible for Prime without
using FBA, the HJC Report characterized that option as “entirely impractical” for “most sellers.” Id.
271 Id. at 288-90.
272 Id. at 287-88.
273 Id. at 292. In 2022, the European Commission accepted certain commitments from Amazon to resolve similar
concerns. See Amazon EC Commitments, supra note 258. Among other things, Amazon agreed to treat all sellers
equally in managing its Buy Box and to allow third-party sellers that participate in Prime to freely choose their logistics
and delivery services. Id.
274 HJC REPORT, supra note 11, at 16; see also Lina M. Khan, The Separation of Platforms and Commerce, 119
COLUM. L. REV. 973, 985-94 (2019) [hereinafter “Khan, Platforms and Commerce”].
275 HJC REPORT, supra note 11, at 274-82; Press Release, Euro. Comm’n, Antitrust: Commission Sends Statement of
Objections to Amazon for the Use of Non-Public Independent Seller Data and Opens Second Investigation into its E-
Commerce Business Practices (Nov. 10, 2020), https://ec.europa.eu/commission/presscorner/detail/en/ip_20_2077.
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During congressional testimony in July 2020, Amazon’s founder and former chief executive said
that the company has a policy against using seller-specific data to aid its private-label business.276
He indicated, however, that he could not guarantee that this policy had never been violated.277
Amazon reportedly does not have a policy against using aggregated seller data to assist its retail
business.278
Commentators have disputed the competitive effects of a platform’s use of user data to enter new
markets. Some commentators have argued that Amazon’s entry into new markets forces other
sellers to lower their prices—an outcome that antitrust traditionally encourages.279 Others contend
that the alleged copying may have longer-term anticompetitive effects by chilling incentives to
innovate.280
Self-Preferencing
Amazon’s dual role as a marketplace operator and private-label seller has led to a range of other
concerns about self-preferencing. For example, a 2016 ProPublica investigation concluded that
Amazon designed the ranking algorithm for its marketplace to favor its own offerings and
products offered by sellers that use FBA.281 The HJC Report also alleged that Amazon has
engaged in other forms of self-preferencing, such as refusing to allow certain competitors to
advertise on Amazon’s platform.282
Predatory Pricing
Amazon has also been accused of engaging in predatory pricing at various points in its history.283
These allegations have been directed against several aspects of Amazon’s business, including its
sale of e-books;284 its sale of diapers and ultimate acquisition of the parent company of
Diapers.com;285 and Amazon Prime.286

276 HJC REPORT, supra note 11, at 277-78.
277 Id.
278 Id. at 278. The European Commission has investigated similar issues. In 2020, the Commission preliminarily
concluded that Amazon had relied on aggregated data generated by third-party sellers to support its own retail
offerings. See Amazon EC Commitments, supra note 258. In December 2022, the Commission accepted Amazon’s
commitment not to use non-public data derived from third-party sellers to assist its private-label business. See id.
279 See, e.g., Francis, supra note 48, at 832; Herbert Hovenkamp, Antitrust and Platform Monopoly, 130 YALE L.J.
1952, 2015 (2021) [hereinafter “Hovenkamp, Platform Monopoly”].
280 ARIEL EZRACHI & MAURICE E. STUCKE, HOW BIG-TECH BARONS SMASH INNOVATION—AND HOW TO STRIKE BACK
54-57 (2022). These issues are discussed in greater detail in infra “Use of Nonpublic User Data.”
281 Julia Angwin & Surya Mattu, Amazon Says It Puts Customers First. But Its Pricing Algorithm Doesn’t, PROPUBLICA
(Sept. 20, 2016), https://www.propublica.org/article/amazon-says-it-puts-customers-first-but-its-pricing-algorithm-
doesnt.
282 HJC REPORT, supra note 11, at 283-86.
283 See, e.g., Shaoul Sussman, Prime Predator: Amazon and the Rationale of Below Average Variable Cost Pricing
Strategies Among Negative-Cash Flow Firms, 7 J. ANTITRUST ENFORCEMENT 203 (2019).
284 Khan, Amazon’s Antitrust Paradox, supra note 57, at 756-68.
285 Id. at 768-74; HJC REPORT, supra note 11, at 297-99.
286 HJC REPORT, supra note 11, at 299-300.
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In academic work, the chair of the FTC has argued that Amazon exemplifies the rationality of
predatory pricing in markets characterized by strong network effects and extreme scale
economies, contrary to the assumptions that underpin current doctrine.287
Other commentators have challenged these allegations.288 In response to the claims involving
Diapers.com, for example, some have noted that Amazon has not been accused of occupying a
monopolistic share of the market for online diaper sales or diaper sales generally.289 Others have
argued that the HJC report failed to produce sufficient evidence to conclude that Amazon prices
Prime memberships below cost.290
Apple
Apple is the most valuable company in the world.291 The firm designs, manufactures, and sells
iPhone smartphones, Mac personal computers, iPad tablets, and several wearables and
accessories, in addition to offering a range of related services.292 The discussion below focuses on
issues related to the company’s mobile operating system and App Store.
Allegations of Market Power
As discussed, Apple’s iOS and Google’s Android are the two dominant operating systems for
mobile devices in the United States and globally.293 More than half of the mobile devices in the
United States run a version or derivation of iOS.294 Apple’s App Store is the only method by
which software developers can distribute apps on iOS devices; Apple does not allow iOS users to
download other app stores or sideload apps.295
Based on these restrictions, Apple’s market share, and various entry barriers, the HJC Report
concluded that Apple has significant and durable market power in markets for mobile operating
systems and mobile app stores.296 The report also alleged that Apple has monopoly power over
app distribution on iOS devices.297
Epic Games—the developer of the video game Fortnite—has made similar claims in litigation,
arguing that Apple has monopoly power in an iOS app distribution market and a market for iOS
in-app payment (IAP) processing.298 (Like Google, Apple requires developers to use its IAP

287 Khan, Amazon’s Antitrust Paradox, supra note 57, at 753, 786, 791-92.
288 Kristian Stout & Alec Stapp, Is Amazon Guilty of Predatory Pricing?, TRUTH ON THE MARKET (May 7, 2019),
https://truthonthemarket.com/2019/05/07/is-amazon-guilty-of-predatory-pricing/; Jeffrey Eisenach, Who Should
Antitrust Protect? The Case of Diapers.com, AM. ENTER. INST. (Nov. 5, 2018), https://www.aei.org/technology-and-
innovation/who-should-antitrust-protect-the-case-of-diapers-com/.
289 Eisenach, supra note 288.
290 Carl Shapiro, Regulating Big Tech: Factual Foundations and Policy Goals, NETWORK L. REV. (forthcoming Fall
2023), https://www.networklawreview.org/shapiro-big-tech/.
291 Largest Companies by Market Cap, COMPANIESMARKETCAP (last visited Mar. 15, 2023),
https://companiesmarketcap.com/.
292 Apple Inc., Annual Report (Form 10-K) at 1-2 (Oct. 28, 2022).
293 HJC REPORT, supra note 11, at 100-02.
294 Id. at 334.
295 Id. at 335.
296 Id. at 334.
297 Id. at 335.
298 Complaint for Injunctive Relief ¶¶ 58, 119, Epic Games, Inc. v. Apple Inc., No. 4:20-cv-05640 (N.D. Cal. Aug. 13,
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processor as a condition of accessing its App Store and has charged 30 percent commissions for
that service.)299
Apple has denied possessing monopoly power. With respect to software distribution, the company
argues that it competes in a market that includes other app stores, the open internet, and physical
retail stores.300 In the Epic Games litigation involving video-game distribution, Apple has
contended that the relevant antitrust market is a market for video game distribution generally,
which includes other app stores, gaming stores for personal computers, gaming stores on game
consoles, and cloud-based game streaming services.301
In September 2021, a federal district court concluded in Epic Games that Apple competes in a
market for digital mobile gaming transactions, as opposed to a broader market for video-game
distribution generally or a narrower market for game distribution on iOS devices.302 The court
further determined that Apple possesses market power—but not monopoly power—in this
market.303 Epic Games has appealed this decision.304
Allegations of Anticompetitive Conduct
Mobile App Distribution and IAP Processing
Apple has been accused of engaging in several anticompetitive practices in app markets.
One set of allegations focuses on various technical and contractual restrictions that prevent
developers from distributing iOS apps outside of the App Store, which allegedly harms
competition in markets for app distribution.305 Epic Games has also argued that the requirement
that developers using Apple’s App Store also use Apple’s IAP processor constitutes an unlawful
tying arrangement.306
A federal district court has rejected these claims. In Epic Games, the court held that the relevant
contractual restrictions on app distribution qualified as unilateral rather than concerted conduct.307
Because the court had determined that Apple was not a monopolist, it rejected the plaintiff’s
claims involving those restrictions.308
While the court concluded that the challenged restrictions were unilateral and thus not illegal
absent monopoly power, it acknowledged certain doctrinal ambiguities involving the distinction

2020).
299 Epic Games, Inc. v. Apple Inc., 559 F. Supp. 3d 898, 923 (N.D. Cal. 2021). In November 2020, Apple reduced its
IAP processing fees from 30 percent to 15 percent for developers with less than $1 million in annual net sales on its
platform. Kif Leswing, Apple Will Cut App Store Commissions by Half to 15% for Small App Makers, CNBC (Nov. 18,
2020), https://www.cnbc.com/2020/11/18/apple-will-cut-app-store-fees-by-half-to-15percent-for-small-
developers.html.
300 HJC REPORT, supra note 11, at 335.
301 Epic Games, Inc., 559 F. Supp. 3d at 972-76.
302 Id. at 921.
303 Id. at 922.
304 Notice of Appeal, Epic Games, Inc. v. Apple Inc., No. 4:20-cv-05640 (N.D. Cal. Sept. 12, 2021).
305 Complaint for Injunctive Relief ¶¶ 64-81, 87-102, Epic Games, Inc. v. Apple Inc., No. 4:20-cv-05640 (N.D. Cal.
Aug. 13, 2020).
306 Id. ¶ 129.
307 Epic Games, Inc. v. Apple Inc., 559 F. Supp. 3d 898, 1035 (N.D. Cal. 2021).
308 Id. at 1044.
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between unilateral and concerted conduct.309 The court thus proceeded to conduct a
competitive-effects analysis of the challenged restrictions notwithstanding its holding that they
were unilateral.310 In conducting this analysis under the rule of reason, the court concluded that:
1. Epic Games had established evidence of the restrictions’ anticompetitive
effects;311
2. Apple had proffered valid procompetitive justifications for the restrictions based
on security concerns, the promotion of interbrand competition, and the protection
of intellectual property;312 and
3. Epic Games had not shown that those procompetitive benefits could be achieved
through less restrictive means.313
Accordingly, the court held that the contractual restrictions on app distribution did not violate
Section 1 of the Sherman Act, even if they amounted to concerted conduct.314
The court went on to reject other Section 1 and Section 2 claims involving app distribution and
IAP processing for similar reasons—namely, the plaintiff’s failure to show that various
procompetitive benefits could be achieved through less restrictive means or establish monopoly
power.315
Finally, the court denied the plaintiff’s tying claim on the grounds that IAP processing does not
represent a separate product from app distribution.316
As noted, Epic Games has appealed the district court’s decision.317 The Ninth Circuit heard oral
arguments in the appeal in November 2022.318
Self-Preferencing
The HJC Report alleged that Apple has taken a variety of steps to preference its own apps and
harm rival app developers.319 Among other things, the report accused Apple of injuring
competition by pre-installing its own apps on iPhones;320 denying third-party apps access to

309 Id. at 1036.
310 Id.
311 Id. at 1036-38.
312 Id. at 1038-40.
313 Id. at 1040-41.
314 Id. at 1041.
315 Id. at 1041-44.
316 Id. at 1047. While the court rejected the plaintiff’s federal antitrust claims, it concluded that Apple’s anti-steering
provisions—which prohibited app developers from including links to external mechanisms for making IAPs—violated
California’s unfair-competition law. Id. at 1058. Apple has cross-appealed that aspect of the district court’s decision.
Notice of Appeal, Epic Games, Inc. v. Apple Inc., No. 4:20-cv-05640 (N.D. Cal. Oct. 8, 2021).
317 Notice of Appeal, Epic Games, Inc. v. Apple Inc., No. 4:20-cv-05640 (N.D. Cal. Sept. 12, 2021).
318 Paresh Dave, Epic’s ‘Failure of Proof’ in Apple Antitrust Case Questioned by Appeals Panel, REUTERS (Nov. 14,
2022), https://www.reuters.com/legal/fortnite-creator-fight-apple-antitrust-ruling-appeal-hearing-2022-11-14/.
319 HJC REPORT, supra note 11, at 352.
320 Id.
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certain APIs and device functionalities that are available to its own apps;321 favoring its own apps
in search results on its App Store;322 and removing rival apps from the App Store.323
Apple has denied giving preferential treatment to its own apps in search rankings and justified
removing specific apps from the App Store as efforts to protect user privacy.324
Use of Competitively Sensitive Information
Like Amazon, Apple has faced allegations that it uses its access to data generated by dependent
businesses to identify and imitate popular offerings.325 In particular, software developers have
accused Apple of using competitively sensitive information about popular apps to build
competing apps and integrate certain functionalities into iOS.326
Apple has responded to questions regarding such allegations by stating that it does not violate
other companies’ intellectual property rights.327
Big Tech Mergers and Acquisitions
Some of the allegations discussed above involve Big Tech mergers and acquisitions. As noted, the
FTC is currently challenging Facebook’s acquisitions of Instagram and WhatsApp,328 while
Google’s acquisition of DoubleClick is a key part of the DOJ’s monopolization lawsuit targeting
the company’s ad-tech practices.329
Some policymakers have expressed broader concerns about Big Tech mergers.330 The companies
have been active dealmakers: between 2000 and 2019, the four firms engaged in hundreds of
mergers and acquisitions.331 Many of these transactions fell below the numerical thresholds that
trigger pre-merger review by the antitrust agencies.332

321 Id. at 354. In May 2022, the European Commission preliminarily determined that Apple had violated European
Union competition law by limiting rival mobile wallet developers from accessing certain technology that Apple makes
available to its own wallet, Apple Pay. See Press Release, Euro. Comm’n, Antitrust: Commission Sends Statement of
Objections to Apple Over Practices Regarding Apple Pay (May 2, 2022), https://ec.europa.eu/commission/presscorner/
detail/en/ip_22_2764.
322 HJC REPORT, supra note 11, at 359-61.
323 Id. at 364-67.
324 Id. at 361, 366.
325 Id. at 361-64.
326 Id. at 362.
327 Id. at 363.
328 FTC v. Facebook, Inc., 581 F. Supp. 3d 34 (D.D.C. 2022).
329 Complaint, United States v. Google LLC, No. 1:23-cv-00108 (E.D. Va. Jan. 24, 2023). For a more detailed
discussion of mergers and acquisitions in tech markets, see CRS Report R46739, Mergers and Acquisitions in Digital
Markets, by Clare Y. Cho.
330 HJC REPORT, supra note 11, at 387; SUBCOMM. ON ANTITRUST, COM., AND ADMIN. L. OF THE H. COMM. ON THE
JUDICIARY, 116TH CONG., THE THIRD WAY: ANTITRUST ENFORCEMENT IN BIG TECH 9 (2020) (written by Ken Buck, et
al. in response to majority report), https://buck.house.gov/sites/evo-subsites/buck-
evo.house.gov/files/wysiwyg_uploaded/Buck%20Report.pdf.
331 Diana L. Moss, The Record of Weak U.S. Merger Enforcement in Big Tech, AM. ANTITRUST INST. 6 (July 8, 2019),
https://www.antitrustinstitute.org/wp-content/uploads/2019/07/Merger-Enforcement_Big-Tech_7.8.19.pdf.
332 FED. TRADE COMM’N, NON-HSR REPORTED ACQUISITIONS BY SELECT TECHNOLOGY PLATFORMS, 2010-2019: AN FTC
STUDY (Sept. 2021), https://www.ftc.gov/system/files/documents/reports/non-hsr-reported-acquisitions-select-
technology-platforms-2010-2019-ftc-study/p201201technologyplatformstudy2021.pdf [hereinafter “FTC Non-
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These deals have prompted some commentators to worry that the Big Tech firms are cementing
their dominant positions by acquiring promising potential competitors.333 Transactions involving
“nascent” competitors have been a particular point of concern.334 While the concept of a
“nascent” competitor has been defined in different ways, it generally refers to an innovative firm
whose technology represents a serious yet uncertain future threat to an incumbent.335
Other commentators have raised concerns about the number of Big Tech mergers that fall below
the thresholds that trigger premerger review by the DOJ and FTC.336
These issues are discussed in greater detail in “Mergers & Acquisitions” infra.337
Antitrust Reform and Big Tech: General Issues
The issues discussed above have prompted calls for policy reform. Some proposals would
supplement the antitrust laws with sectoral competition regulations directed at large technology
platforms.338 Others would work within the existing antitrust framework by adjusting burdens of
proof and changing certain doctrinal rules.339
While the relevant options are varied, they all implicate the threshold question of whether the
existing antitrust laws are adequate to address competition issues in the tech sector.

Reportable Acquisitions Study”].
333 JONATHAN B. BAKER, THE ANTITRUST PARADIGM: RESTORING A COMPETITIVE ECONOMY 160-61 (2019); Steven C.
Salop, Dominant Digital Platforms: Is Antitrust Up to the Task?, 130 YALE L.J. F. 563, 578-79 (2021); Mark Glick, et
al., Big Tech’s Buying Spree and the Failed Ideology of Competition Law, 72 HASTINGS L.J. 465, 468-75 (2021); HJC
REPORT, supra note 11, at 387; Tim Wu & Stuart A. Thompson, The Roots of Big Tech Run Disturbingly Deep, N.Y.
TIMES (June 7, 2019), https://www.nytimes.com/interactive/2019/06/07/opinion/google-facebook-mergers-acquisitions-
antitrust.html; STIGLER CTR. FOR THE STUDY OF THE ECON. AND THE STATE, STIGLER COMM. ON DIGITAL PLATFORMS:
FINAL REPORT 71-72, 75 n.152 (2019), https://www.chicagobooth.edu/-/media/research/stigler/pdfs/digital-platforms---
committee-report---stigler-center.pdf [hereinafter “STIGLER REPORT”]; HM TREASURY, UNLOCKING DIGITAL
COMPETITION, REPORT OF THE DIGITAL COMPETITION EXPERT PANEL 40 (2019),
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/785547/unlocking_di
gital_competition_furman_review_web.pdf [hereinafter “UK DIGITAL COMPETITION REPORT”]
334 A. Douglas Melamed, Mergers Involving Nascent Competition, Stanford L. and Econ. Olin Working Paper No. 566
(Jan. 17, 2022), https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4009229; John M. Yun, Are We Dropping the
Crystal Ball? Understanding Nascent & Potential Competition in Antitrust, 104 MARQ. L. REV. 613 (2021); C. Scott
Hemphill & Tim Wu, Nascent Competitors, 168 U. PA. L. REV. 1879 (2020); OECD, START-UPS, KILLER ACQUISITIONS
AND MERGER CONTROL 21-36 (2020), https://www.oecd.org/daf/competition/start-ups-killer-acquisitions-and-merger-
control-2020.pdf [hereinafter “OECD STARTUP ACQUISITION REPORT”].
335 Yun, supra note 334, at 626-29; Hemphill & Wu, supra note 334, at 1883.
336 STIGLER REPORT, supra note 333, at 111.
337 The FTC was unsuccessful in its first effort to block a Big Tech merger using a potential-competition theory. In
January 2023, a federal district court denied the FTC’s motion for an injunction against Meta’s proposed acquisition of
Within Unlimited—the developer of a virtual-reality (VR) fitness app. Order Denying Plaintiff’s Motion for
Preliminary Injunction, FTC v. Meta Platforms Inc., No. 5:22-cv-04325 (N.D. Cal. Jan. 31, 2023). In that case, Meta
was the putative potential entrant. The FTC alleged that, absent the acquisition, Meta would have organically entered
the market for VR fitness apps. Id. at 39. The Commission also offered a perceived-potential-competition argument,
contending that the prospect of Meta’s entry exerted competitive pressures on that market. Id. at 60. The district court
rejected both theories, concluding that the FTC failed to establish a “reasonable probability” of entry absent the
acquisition or that Meta was perceived as a potential competitor. Id. at 59, 62.
338 See infra “Ex Ante Conduct Rules,” “Structural Separation and Line-of-Business Restrictions,” “Mergers &
Acquisitions” & “Interoperability & Data Portability.”
339 See infra “Changes to General Antitrust.”
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The proposals that would supplement antitrust with a new regulatory regime also raise additional
questions of policy design—namely, how to scope the relevant regulations and select an
appropriate regulator to administer them.
This section of the report discusses these general issues in the debate over antitrust reform
directed at Big Tech firms.
Is Existing Antitrust Law Insufficient?
Whether antitrust is ill-equipped to deal with competition issues in the tech industry has been the
subject of debate.
Reform proponents have alleged that current law is inadequate for two general reasons. First, they
argue that ex post adjudication is ill-equipped to address competition concerns raised by the
unique structure of certain tech markets.340 Second, they contend that several elements of
substantive antitrust doctrine insulate Big Tech firms from liability for specific types of
anticompetitive conduct.341
Market Structure and the Efficacy of Ex Post Adjudication
As discussed, outside of a narrow set of per se offenses, antitrust is a fact-specific enterprise.
Generally, courts employ a case-by-case approach to evaluate claims of anticompetitive
behavior.342 Because liability typically depends on case-specific facts rather than the application
of bright-line rules, antitrust investigations and litigation are often time-consuming and
expensive.343 The open-ended nature of the relevant legal standards can also make it difficult to
predict whether particular conduct violates the law, which may undermine enforcement by
allowing large firms to profit from anticompetitive conduct and treat potential lawsuits as a cost
of doing business.344
Advocates of reform have argued that these features of antitrust adjudication make it ill-suited to
deal with tech markets characterized by a unique confluence of structural characteristics, such as
strong network effects, economies of scale, economies of scope derived from user data, and
consumer tendencies to single home.345

340 See, e.g., OECD, EX ANTE REGULATION AND COMPETITION IN DIGITAL MARKETS 6 (2021),
https://www.oecd.org/daf/competition/ex-ante-regulation-and-competition-in-digital-markets-2021.pdf [hereinafter
“OECD REGULATION REPORT”]; STIGLER REPORT, supra note 333, at 100; UK DIGITAL COMPETITION REPORT, supra
note 333, at 123-24.
341 See, e.g., HJC REPORT, supra note 11, at 395-99.
342 William P. Rogerson & Howard Shelanski, Antitrust Enforcement, Regulation, and Digital Platforms, 168 U. PA. L.
REV. 1911, 1917-18 (2020).
343 Rohit Chopra & Lina M. Khan, The Case for “Unfair Methods of Competition” Rulemaking, 87 U. CHI. L. REV.
357, 360-62 (2020); Daniel A. Crane, Rules Versus Standards in Antitrust Adjudication, 64 WASH. & LEE L. REV. 49,
83 (2007).
344 Chopra & Khan, supra note 343, at 360-61.
345 OECD REGULATION REPORT, supra note 340, at 9-12; STIGLER REPORT, supra note 333, at 7-8, 99; UK DIGITAL
COMPETITION REPORT, supra note 333, at 5. While many markets have one or more of these features, some
commentators have argued that their combination and strength in digital-platform markets raise unique challenges for
antitrust enforcers. See, e.g., Michael Kades & Fiona Scott Morton, Interoperability as a Competition Remedy for
Digital Networks, WASH. CTR. FOR EQUITABLE GROWTH 7 n.14 (Sept. 23, 2020), https://equitablegrowth.org/working-
papers/interoperability-as-a-competition-remedy-for-digital-networks/.
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According to some, these characteristics cause certain tech markets to tip in favor of a single
dominant firm.346 After an initial period of competition, one company may gain an edge that
becomes self-reinforcing. For example, a platform with a large user base and associated data
advantages may be the most attractive to new users, generating a positive feedback loop that
allows it to grow even larger and thereby become even more attractive.347 Prospective entrants
may then face difficulties achieving the scale necessary to compete with the dominant
incumbent.348
Big Tech firms may also derive benefits from their roles as gatekeepers for key digital
ecosystems, like mobile operating systems, app stores, online marketplaces, and social
networks.349 By controlling access to these ecosystems and setting the rules within them, tech
platforms can allegedly preserve their dominant positions and leverage those positions to obtain
advantages in related markets.350
Some analysts contend that antitrust adjudication is too slow to adequately police markets
characterized by these winner-take-all dynamics.351 By the time a market has tipped, they argue,
remedies for anticompetitive conduct may be unable to restore meaningful competition.352
These worries have prompted calls for prophylactic rules to supplement case-by-case antitrust
adjudication.353 Some proposals would also seek to address structural issues in Big Tech markets
by imposing affirmative duties designed to catalyze competition.354
Other commentators have rejected the claim that antitrust is unable to grapple with competition
issues involving large digital platforms. Some, for example, dispute the proposition that Big Tech
markets have all decisively tipped in favor of a single firm.355 Rather, they contend that the tech

346 EZRACHI & STUCKE, supra note 280, at 10-11; OECD REGULATION REPORT, supra note 340, at 9; STIGLER REPORT,
supra note 333, at 34-36; UK DIGITAL COMPETITION REPORT, supra note 333, at 4.
347 Michael L. Katz & Carl Shapiro, Systems Competition and Network Effects, 8 J. ECON. PERSP. 93, 105-06 (1994).
348 Joseph Farrell & Paul Klemperer, Coordination and Lock-In: Competition with Switching Costs and Network
Effects, in 3 HANDBOOK OF INDUSTRIAL ORGANIZATION 1970, 1974 (Mark Armstrong & Robert H. Porter eds., 2007).
349 EZRACHI & STUCKE, supra note 280, at 45-50; Marco Cappai & Giuseppe Colangelo, Taming Digital Gatekeepers:
The More Regulatory Approach to Antitrust Law, Stanford-Vienna TTLF Working Paper 9 (Stanford-Vienna TTLF,
Working Paper No. 55, 2020).
350 OECD REGULATION REPORT, supra note 340, at 10.
351 Giorgio Monti, The Digital Markets Act—Institutional Design and Suggestions for Improvement 1 (Tilburg L. &
Econ. Ctr., Discussion Paper No. 2021-04, 2021); STIGLER REPORT, supra note 333, at 99; UK DIGITAL COMPETITION
REPORT, supra note 333, at 6.
352 EZRACHI & STUCKE, supra note 280, at 173-75; Monti, supra note 351, at 1; STIGLER REPORT, supra note 333, at 99;
UK DIGITAL COMPETITION REPORT, supra note 333, at 6.
353 E.g., STIGLER REPORT, supra note 333, at 100-01; UK DIGITAL COMPETITION REPORT, supra note 333, at 62-63.
Proposals involving ex ante conduct rules for Big Tech firms are discussed in “Ex Ante Conduct Rules” infra.
354 E.g., Rogerson & Shelanski, supra note 342, at 1927-30. Proposals involving these types of affirmative obligations
are discussed in “Interoperability & Data Portability” infra.
355 E.g., Hovenkamp, Platform Monopoly, supra note 279, at 1978; Joint Submission of Antitrust Economists, Legal
Scholars, and Practitioners to the House Judiciary Committee on the State of Antitrust Law and Implications for
Protecting Competition in Digital Markets at 3-4 (May 15, 2020), https://gai.gmu.edu/wp-content/uploads/sites/
27/2020/05/house_joint_antitrust_letter_20200514.pdf [hereinafter “Antitrust Economist Submission”]; see also
NICOLAS PETIT, BIG TECH AND THE DIGITAL ECONOMY: THE MOLIGOPOLY SCENARIO 153-71, 257 (2020) (arguing that
Big Tech firms face meaningful competitive pressures even when operating in tipped markets); How Tech’s Defiance
of Economic Gravity Came to an Abrupt End, THE ECONOMIST (Dec. 24, 2022), https://www.economist.com/business/
2022/12/24/how-techs-defiance-of-economic-gravity-came-to-an-abrupt-end (arguing that some Big Tech firms face
“fierce” competition from one another and from new rivals); Ryan Bourne & Rachel Chiu, A Monopoly of What? Big
Tech in Today’s Context, CATO INST. (Nov. 3, 2022), https://www.cato.org/commentary/monopoly-what-big-tech-
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giants compete in diverse markets characterized by different competitive dynamics.356 While
some of those markets may be susceptible to tipping, others arguably retain a competitive fringe
or exhibit competition among rivals of comparable size.357
Defenders of the adjudicative model of antitrust enforcement have thus emphasized the
heterogeneity of digital-platform markets, which they contend militates against categorical
treatment of Big Tech firms and in favor of the existing fact-specific approach.358
Substantive Antitrust Doctrine
Support for fact-specific adjudication over regulation does not necessarily entail wholesale
endorsement of prevailing antitrust doctrine. Commentators with diverse antitrust ideologies have
argued that certain features of substantive antitrust law allow some types of anticompetitive
conduct by Big Tech platforms to escape liability. Among other things, they have criticized the
doctrine governing unilateral refusals to deal,359 monopoly leveraging,360 predatory pricing,361 and
mergers involving potential and “nascent” competitors.362
These topics are discussed in greater detail throughout the remainder of this report. For purposes
of this section, the important point is that alleged doctrinal infirmities represent a concern that is
distinct from dissatisfaction with adjudication as an enforcement mechanism. A lawmaker’s
preferred policy response may vary based on this distinction. As discussed below, some reform

todays-context (similar); D. Daniel Sokol & Jingyuan (Mary) Ma, Understanding Online Markets and Antitrust
Analysis, 15 NW. J. TECH. & INTELL. PROP. 43, 48-50 (2017) (“Online markets are constantly transforming. Indeed,
online markets typically have innovative challengers against incumbents. Challengers may overtake incumbent firms
through new ideas and technologies. In such settings, there are low entry barriers.”).
356 PETIT, supra note 355, at 257-58; Hovenkamp, Platform Monopoly, supra note 279, at 1978; Joshua D. Wright &
John M. Yun, Platforms in the Spotlight at FTC Hearings, Geo. Mason L. & Econ. Research Paper No. 18-44 at 3
(Nov. 2018), https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3280532.
357 Hovenkamp, Platform Monopoly, supra note 279, at 1978.
358 Id.; Antitrust Economist Submission, supra note 355, at 8-9; see also C.D. HOWE INST. COMPETITION POL’Y
COUNCIL, DIGITAL PLATFORMS: OVERSIGHT IF NECESSARY, BUT NOT NECESSARILY REGULATION 7-8 (2021),
https://www.cdhowe.org/sites/default/files/attachments/other-research/pdf/Communique_2021_0107_CPC.pdf (arguing
that general competition law should be the presumptive framework for addressing competition issues in the tech sector
and that special competition regulations for digital platforms are likely to overlook important distinctions among
heterogeneous business models); ABA ANTITRUST L. SECTION, COMMON ISSUES RELATING TO THE DIGITAL ECONOMY
AND COMPETITION, REPORT OF THE INTERNATIONAL DEVELOPMENTS AND COMMENTS TASK FORCE ON POSITIONS
EXPRESSED BY THE ABA ANTITRUST LAW SECTION BETWEEN 2017 AND 2019, at 5 (2020) [hereinafter “ABA DIGITAL
ECONOMY REPORT”] (concluding that antitrust authorities should address competition issues in digital-platform markets
on a case-by-case basis using existing tools); Group of Seven (G7), Common Understanding of G7 Competition
Authorities on “Competition and the Digital Economy” (June 5, 2019),
https://www.autoritedelaconcurrence.fr/sites/default/files/2019-11/g7_common_understanding.pdf (“Because of its
flexible analytical framework, fact-based analysis, cross-sector application, and technology-neutral nature, competition
law can effectively apply to digital markets and to harmful anticompetitive behaviors in the digital economy.”).
359 Erik Hovenkamp, The Antitrust Duty to Deal in the Age of Big Tech, 131 YALE L.J. 1483, 1525 (2022) [hereinafter
“Hovenkamp, Antitrust Duty to Deal”]; HJC REPORT, supra note 11, at 397-98; STIGLER REPORT, supra note 333, at
96-97; Sandeep Vaheesan, Reviving an Epithet: A New Way Forward for the Essential Facilities Doctrine, 2010 UTAH
L. REV. 911 (2010).
360 HJC REPORT, supra note 11, at 396.
361 Marshall Steinbaum & Maurice E. Stucke, The Effective Competition Standard: A New Standard for Antitrust, 87 U.
CHI. L. REV. 595, 608 (2020); HJC REPORT, supra note 11, at 396-97; Aaron S. Edlin, Stopping Above-Cost Predatory
Pricing, 111 YALE L.J. 941 (2002).
362 Hemphill & Wu, supra note 334; Kevin A. Bryan & Erik Hovenkamp, Antitrust Limits on Startup Acquisitions, 56
REV. OF INDUS. ORG. 615, 632 (2020); HJC REPORT, supra note 11, at 394-95.
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proposals target large tech platforms with sectoral regulations that would supplement the antitrust
laws, while others would make changes within general antitrust doctrine.363
These debates over specific doctrinal rules take place alongside broader contestation regarding
the fundamental goals of antitrust. A group of scholars and policymakers commonly identified as
“Neo-Brandeisians” have called for the abandonment of the consumer-welfare standard as a
benchmark for antitrust decision-making.364 Members of this movement have argued that a
singular focus on consumer welfare has led to lax competition enforcement, which has in turn
generated rising economic concentration, growing wealth inequality, and a political system
captured by corporate interests.365
Some Neo-Brandeisians have specifically emphasized the consumer-welfare standard’s alleged
inadequacy vis-à-vis large tech platforms. In particular, they contend that a focus on short-term
price and output effects neglects the ways in which tech platforms forgo immediate profits to
establish long-term dominance and then leverage that dominance across business lines.366
Defenders of the consumer-welfare standard fall into two broad camps. Some commentators join
the Neo-Brandeisians in arguing that antitrust enforcement has become overly lax, but support the
retention of the consumer-welfare standard as a general goal.367 While they object to specific
doctrinal developments, these commentators attribute such developments to misapplications of
the consumer-welfare standard rather than the standard itself.368 In contrast, others have defended
both the consumer-welfare standard and current levels of antitrust enforcement.369
Among other things, supporters of the consumer-welfare standard have argued that many
Neo-Brandeisian criticisms are based on an inaccurate view that the standard focuses solely on
price to the exclusion of other benefits of competition, like innovation and product quality.370
Abstracting from the merits of the Neo-Brandeisian critique, the possible repudiation of the
consumer-welfare standard raises the question of whether an alternative benchmark would replace
it.
Several options have been proposed. Some critics of the status quo have argued that antitrust
should focus on the “competitive process.”371 That phrase has been used for a variety of

363 See infra “Reform Proposals.”
364 See, e.g., TIM WU, THE CURSE OF BIGNESS: ANTITRUST IN THE NEW GILDED AGE 135-38 (2018); Sandeep Vaheesan,
The Profound Nonsense of the Consumer Welfare Standard, 64 ANTITRUST BULL. 479 (2019); Khan, Amazon’s
Antitrust Paradox, supra note 57, at 744-46. The Neo-Brandeisian movement derives its name from Louis Brandeis, a
former Associate Justice of the Supreme Court who was also a proponent of vigorous antitrust enforcement and a critic
of large corporations. See Lina M. Khan, The New Brandeis Movement: America’s Antimonopoly Debate, 9 J. EURO.
COMPETITION L. & PRACTICE 131 (2018).
365 Lina M. Khan & Sandeep Vaheesan, Market Power and Inequality: The Antitrust Counterrevolution and Its
Discontents, 11 HARV. L. & POL’Y REV. 235 (2017).
366 Khan, Amazon’s Antitrust Paradox, supra note 57, at 747-53, 774-80.
367 See, e.g., Einer Elhauge, Should the Competitive Process Test Replace the Consumer Welfare Standard?,
PROMARKET (May 24, 2022), https://www.promarket.org/2022/05/24/should-the-competitive-process-test-replace-the-
consumer-welfare-standard/; Moss Testimony, supra note 152; Shapiro Testimony, supra note 152.
368 A. Douglas Melamed, Antitrust Law and Its Critics, 83 ANTITRUST L.J. 269, 274-79 (2020) (discussing several
points of disagreement between “conservatives” and “mainstream progressives” working within the consumer-welfare
paradigm).
369 See, e.g., Antitrust Economist Submission, supra note 355, at 4-12.
370 Melamed, supra note 368, at 281; Dorsey, et al., supra note 149, at 902; Moss Testimony, supra note 152, at 4.
371 E.g., HJC REPORT, supra note 11, at 391-92; Tim Wu, The “Protection of the Competitive Process” Standard,
(Colum. Pub. L. Research Paper No. 14-612, 2018), https://scholarship.law.columbia.edu/cgi/
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purposes,372 but in this context appears intended to signify a standard that would protect “not just
consumers, but also workers, entrepreneurs, independent businesses, open markets, a fair
economy, and democratic ideals.”373 In other work, Neo-Brandeisians have advocated a “citizen
interest” standard that would “protect consumers from anticompetitive overcharges and small
producers from anticompetitive underpayments, preserve open markets, and disperse economic
and political power.”374
Proponents of these approaches have argued that they are more normatively attractive than the
consumer-welfare standard and better reflect the full range of considerations that originally
motivated the antitrust laws.375 Critics have contended that the proposed alternatives embrace
vague and often contradictory goals and thus offer little guidance regarding the types of conduct
that they would prohibit or allow.376
These debates are not purely academic. As discussed below, some legislative proposals would
subject large tech platforms to special conduct rules that incorporate competitive-effects analysis,
either as an element of a plaintiff’s case-in-chief or as an affirmative defense.377 The appropriate
standard for assessing competitive harm may thus have important practical consequences beyond
its significance in current doctrine.
Error Costs in Digital Markets
Modern antitrust has been heavily influenced by concerns about error costs—the harms that result from decisions
prohibiting procompetitive conduct (false positives) or permitting anticompetitive conduct (false negatives). Alan
Devlin & Michael Jacobs, Antitrust Error, 52 WM. & MARY L. REV. 75, 78-79 (2010).
Antitrust conservatives have offered error-cost arguments favoring limited enforcement. In a 1984 article, Frank
Easterbrook—now a federal judge on the Seventh Circuit—argued that false positives are more harmful than false
negatives. Frank H. Easterbrook, The Limits of Antitrust, 63 TEX. L. REV. 1, 2 (1984). He reasoned that the force of
judicial precedent makes false positives difficult to correct, but that monopoly profits eventually induce the entry
of new firms, mitigating the costs of false negatives. Id. Several Supreme Court decisions later relied upon this

viewcontent.cgi?article=3293&context=faculty_scholarship; Khan, Amazon’s Antitrust Paradox, supra note 57, at 745.
372 See Herbert Hovenkamp, The Slogans and Goals of Antitrust Law 51-58 (U. Penn. Inst. for L. & Econ. Research
Paper No. 22-33, 2022), https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4121866#.
373 HJC REPORT, supra note 11, at 391; see also Steinbaum & Stucke, supra note 361, at 602 (proposing an “effective
competition” standard under which “[a]gencies and courts shall use the preservation of competitive market structures
that protect individuals, purchasers, consumers, and producers; preserve opportunities for competitors; promote
individual autonomy and well-being; and disperse private power as the principal objective of the federal antitrust
laws.”).
374 Khan & Vaheesan, supra note 365, at 276.
375 WU, supra note 364, at 135-38; Steinbaum & Stucke, supra note 361, at 621-23 & n.91; Khan & Vaheesan, supra
note 365, at 276.
376 Dorsey, et al., supra note 149, at 879; Joshua D. Wright, et al., Requiem for a Paradox: The Dubious Rise and
Inevitable Fall of Hipster Antitrust, 51 ARIZ. ST. L. J. 292, 362-65 (2019); see also Hovenkamp, supra note 372, at 54
(“[A]n antitrust concern articulated as the protection of the competitive process does not give us much help unless we
have some background substance to tell us what is intelligent competition policy and what is not.”); Elhauge, supra
note 367 (arguing that a “competitive process” standard that lacks any supplemental benchmark “amounts to a
conclusory I-know-it-when-I-see-it test”); John M. Newman, Procompetitive Justifications in Antitrust Law, 94 IND.
L.J. 501, 514 (2019) (“[T]he actual content of the competitive-process approach remains mercurial, a cipher. The
scholarly arguments in favor of it never seem to identify what, exactly, constitutes the ‘competitive process.’”); Daniel
A. Crane, Four Questions for the Neo-Brandeisians, COMPETITION POL’Y INT’L ANTITRUST CHRON. 63, 66-67 (Apr.
2018) (“[W]hat would happen in a system that was nominally designed to protect consumers, workers, labor unions,
small businesses, new entrants, and existing competitors all at once? Since the interests of those groups are often in
conflict, courts and agencies would have to pick their favorites on the fly, without any objective principle to decide
among them.”).
377 See infra “Self-Preferencing / Non-Discrimination Rules.”
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analysis to justify holdings narrowing various aspects of antitrust doctrine. Herbert J. Hovenkamp, Antitrust Error
Costs, U. PA. J. BUS. L. 293, 295-96 (2022) (col ecting cases).
Courts and commentators have grappled with error-cost issues in digital markets. In its 2001 decision in United
States v. Microsoft Corp., the D.C. Circuit relied on the novelty of platform software products to conclude that the
rule of reason—rather than the traditional rule of quasi-per-se il egality—applied to a challenged tying arrangement
involving such products. 253 F.3d 34, 89-90 (D.C. Cir. 2001) (per curiam). Other courts and commentators have
likewise emphasized the complexity and dynamism of tech markets in arguing for a cautious approach to antitrust
intervention. See FTC v. Qualcomm Inc., 969 F.3d 974, 990-91 (9th Cir. 2020); Rachel S. Tennis & Alexander Baier
Schwab, Business Model Innovation and Antitrust Law, 29 YALE J. ON REG. 307, 319 (2012).
This reasoning is controversial. Some observers have mounted general challenges to the claim that error costs
justify permissive antitrust doctrine. See, e.g., Jonathan B. Baker, Taking the Error Out of “Error Cost” Analysis: What’s
Wrong with Antitrust’s Right, 80 ANTITRUST L.J. 1, 8-12, 23-25 (2015) (disputing the arguments that markets are
self-correcting and that erroneous judicial precedent is more durable than market power).
Others have focused their critique on digital markets. For example, John Newman—now the Deputy Director of
the FTC’s Bureau of Competition—has argued that false negatives in tech markets are far more common and
costly than false positives. John M. Newman, Antitrust in Digital Markets, 72 VAND. L. REV. 1497, 1502 (2019). In
particular, Newman contends that the structure of many digital markets insulates incumbents from competitive
threats; that digital markets provide incumbents with unique anticompetitive strategies; and that challenged
conduct in digital markets typically has few redeeming benefits. Id. at 1503-48. These features, he maintains, justify
more vigilant antitrust scrutiny of tech markets, contrary to what he characterizes as the “orthodox” view of
error costs. Id. at 1502.
These error-cost debates have important implications for the choice between adjudication and regulation as
enforcement mechanisms and the appropriate content of antitrust doctrine.
Scoping Reform Proposals
Reform proposals that would go beyond general antitrust to impose sectoral competition
regulations raise additional questions of policy design. Two general models have emerged.
One would apply special regulations to digital platforms that offer specified services and meet
certain quantitative and qualitative criteria intended to capture platforms with bottleneck power
over business users.378 Because proposals in this category involve the designation of covered
platforms by regulators, this report refers to this strategy as the “designated-platform
approach.”379
The second model is narrower. While the designated-platform approach would apply the same set
of regulations to covered firms in a range of markets (e.g., social networking, e-commerce, online
search), some legislation would apply only to individual markets.380 This report refers to this
strategy as the “market-specific approach.”
The subsections below review these two models for sector-specific competition regulation.
The Designated-Platform Approach
Policymakers in the United States and EU have explored the designated-platform approach. The
EU has adopted legislation titled the Digital Markets Act, which applies special regulations to

378 See infra “The Designated-Platform Approach.”
379 As drafted, some of these proposals would apply special regulations to platforms meeting the relevant criteria even
if the platforms are not formally designated by a regulator. See, e.g., American Innovation and Choice Online Act, H.R.
3816, 117th Cong. § 2(g)(4) (2021) (Reported Version). Nevertheless, this report adopts the terminology noted above
because of the central role that designation would likely have played in the bills’ application.
380 See infra “Market-Specific Regulation.”
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designated “gatekeepers.”381 Firms are to be designated as “gatekeepers” if they offer certain
“core platform services”—including search engines, app stores, operating systems, advertising
services, social networking, and online marketplaces—and meet certain quantitative and
qualitative criteria.382
In the United States, several bills in the 117th Congress would have adopted a broadly similar
approach.383 Under the bills, “covered platforms” would have included search engines, app stores,
operating systems, social networks, and online marketplaces that meet specified quantitative and
qualitative criteria.384
The proposals would have empowered the DOJ and FTC to designate a platform offering any of
these services as a covered platform based on (1) quantitative thresholds involving market
capitalization, annual sales, and active users, and (2) the platform’s status as a “critical trading
partner.”385
Different bills would have imposed different types of competition regulations on designated
platforms, including rules involving discriminatory conduct against business users,386 vertical
integration,387 and mergers.388
Depending on the interpretation of the “critical trading partner” standard, the designation criteria
may have encompassed the platforms discussed earlier in this report:
 Facebook, Instagram, and WhatsApp (which are controlled by Meta Platforms);
 Google Search, Android, the Google Play Store, and some of Google’s ad-tech
services;
 Amazon Marketplace; and
 Apple’s iOS and App Store.389
Certain Microsoft properties and TikTok—a short-form video app controlled by the Chinese firm
ByteDance—may also have fallen within the bills’ coverage.390
The designation criteria employed in these proposals raised several issues. Some commentators
criticized the use of market capitalization and annual sales as factors that would have determined

381 Press Release, Euro. Comm’n, Digital Markets Act: Rules for Digital Gatekeepers to Ensure Open Markets Enter
Into Force (Oct. 31, 2022), https://ec.europa.eu/commission/presscorner/detail/en/IP_22_6423.
382 Id.
383 American Innovation and Choice Online Act, S. 2992, 117th Cong. § 3(d) (2022) (Reported Version); Platform
Competition and Opportunity Act of 2021, S. 3197, 117th Cong. § 4 (2021); ACCESS Act of 2021, H.R. 3849, 117th
Cong. § 6 (2021); Platform Competition and Opportunity Act of 2021, H.R. 3826, 117th Cong. § 4 (2021); Ending
Platform Monopolies Act, H.R. 3825, 117th Cong. § 6 (2021); H.R. 3816 at § 2(d).
384 See, e.g., S. 2992 § 2(a)(9).
385 See, e.g., id. §§ 2(a)(5), 3(d).
386 S. 2992; H.R. 3816.
387 H.R. 3825.
388 H.R. 3826. Another proposal—which would have imposed interoperability and data-portability obligations on
covered platforms—employed the same general designation standards as the other bills, but would have provided for
firm-specific standards rather than categorical regulatory treatment of covered firms. H.R. 3849.
389 Leah Nylen, Tech Antitrust Bill Threatens to Break Apple, Google’s Grip on the Internet, BLOOMBERG (July 26,
2022), https://www.bloomberg.com/graphics/2022-tech-antitrust-bill/#xj4y7vzkg.
390 Id.
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a firm’s regulatory status.391 Those criteria, they contended, have little relevance for a platform
operator’s ability to harm competition, which instead depends on a firm’s market power.392 As
discussed, courts typically assess claims of market power by evaluating a firm’s size within a
relevant antitrust market—not its absolute size.393 Critics of the designated-platform bills thus
argued that the proposals employed arbitrary designation criteria intended to single out a small
handful of firms.394
The bills sought to address some of these concerns about arbitrariness with the additional
requirement that covered platforms include only “critical trading partners”—a term defined to
mean persons with the ability to “restrict or impede” a business user’s access to customers or
tools or services needed to effectively serve customers.395 This phrase would have represented a
novel addition to the antitrust lexicon.
The use of the new “critical trading partner” language instead of the more familiar concept of
market power may have been a response to some of the more demanding elements of
market-power doctrine. Market definition—which is required if a plaintiff seeks to establish
market power via market-share evidence—often involves a costly and time-consuming battle of
economic experts.396 The “critical trading partner” terminology may have been motivated in part
by a desire to ease these burdens.
Some commentators have also lodged theoretical objections to the centrality of market definition
in contemporary antitrust.397 Among other things, they have highlighted the limitations of binary
market analysis when it comes to differentiated products.398 Products that fall within a relevant

391 Erik Hovenkamp, Proposed Antitrust Reforms in Big Tech: What Do They Mean for Competition and Innovation?,
COMPETITION POLICY INT’L ANTITRUST CHRONICLE 15, 22 (July 2022) [hereinafter “Hovenkamp, Proposed Antitrust
Reforms”]; AURELIAN PORTUESE, INFO. TECH. & INNOVATION FDN., THE REVISED (BUT UNCORRECTED) VERSION OF THE
KLOBUCHAR BILL (2022), https://www2.itif.org/2022-revised-uncorrected-klobuchar-bill.pdf; Comments of the
American Bar Association Antitrust Law Section Regarding the American Innovation and Choice Online Act (S. 2992)
Before the 117th Congress 8 (Apr. 27, 2022), https://www.americanbar.org/content/dam/aba/
administrative/antitrust_law/comments/at-comments/2022/comments-aico-act.pdf [hereinafter “ABA Letter”].
392 Hovenkamp, Proposed Antitrust Reforms, supra note 391, at 22; PORTUESE, supra note 391; ABA Letter, supra note
391, at 8.
393 ELHAUGE, supra note 30, at 226.
394 E.g., Herbert Hovenkamp, Gatekeeper Competition Policy 18 (U. of Penn., Inst. for L. & Econ., Research Paper No.
23-08, 2023), https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4347768 [hereinafter “Hovenkamp, Gatekeeper
Competition Policy”] (arguing that the strategy of designating platforms based on size rather than market share suggests
an intent to protect the rivals of covered platforms from aggressive competition rather than a desire to protect
consumers); PORTUESE, supra note 391.
395 E.g., American Innovation and Choice Online Act, H.R. 3816, 117th Cong. §§ 2(g)(4)(B)(iii), 2(g)(5) (2021)
(Reported Version). One of the bills defined the term “critical trading partner” to mean a person with the ability to
“restrict or materially impede” a business user’s access to customers or tools needed to effectively serve customers.
American Innovation and Choice Online Act, S. 2992, 117th Cong. § 2(a)(6) (2022) (Reported Version) (emphasis
added). For a more detailed discussion of the American Innovation and Choice Online Act, see CRS Report R47228,
The American Innovation and Choice Online Act, by Jay B. Sykes.
396 See Hovenkamp, The Rule of Reason, supra note 27, at 98-99 (discussing the administrative costs associated with
the rule of reason); John E. Lopatka & William H. Page, Economic Authority and the Limits of Expertise in Antitrust
Cases, 90 CORNELL L. REV. 617, 659-60 (2005) (noting that modern courts recognize that “market definition requires
the sophisticated use of data and theory,” which in turn requires expert testimony).
397 Louis Kaplow, Why (Ever) Define Markets?, 124 HARV. L. REV. 437, 476-79 n.78-79 (2010) (cataloguing academic
criticisms of the role that market definition plays under current law).
398 Hovenkamp, Platform Monopoly, supra note 279, at 1961 (“If a market is product-differentiated, any conclusion
about market definition is wrong.”); Joseph Farrell & Carl Shapiro, Antitrust Evaluation of Horizontal Mergers: An
Economic Alternative to Market Definition, 10 B.E. J. OF THEORETICAL ECON. art. 9 at 4 (2010) (“Product
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antitrust market, for example, all count as equally effective substitutes for the product at issue; the
market-definition paradigm does not consider different rates of substitution among products
within a relevant market.399 Similarly, firms deemed to fall outside a relevant market are treated
as if they exert no competitive pressure on a defendant.400
Reality is often more nuanced. In markets with differentiated products—like many technology
markets—there may be a range of firms that compete with a defendant to various degrees.
Singling out a specific market boundary along this type of continuum may thus yield inaccurate
assessments of market power.401
Other commentators have expressed narrower concerns about current market-power doctrine. For
example, some have argued that the Supreme Court’s 2018 decision in Ohio v. American Express
(Amex)402—which adopted special market-definition rules for two-sided transaction platforms—
may hamper antitrust enforcement against some tech firms.403
The “critical trading partner” requirement thus appeared to respond to dissatisfaction with
existing case law. However, many argued that the requirement’s precise relationship with current
doctrine was unclear. The core concern of market definition—the availability of reasonable
substitutes—seems relevant to whether a platform has the ability to “restrict or impede” a
business user’s access to customers or necessary tools. As a result, some of the considerations that
figure in market definition would potentially have played a role in evaluations of the “critical
trading partner” requirement. The exact ways in which this inquiry may have differed from
traditional market definition accordingly remained uncertain.
The literature also reflected different views of the requirement’s stringency. Some commentators
argued that the relevant bills were “carefully targeted” because they would have applied only to
“critical trading partners.”404 Others contended that the additional criterion would have been
unlikely to exclude firms that met the bills’ quantitative thresholds.405 The analytical framework

differentiation can make defining the relevant market problematic, notably because products must be ruled ‘in’ or ‘out,’
creating a risk that the outcome of a merger investigation or case may turn on an inevitably artificial line-drawing
exercise.”).
399 Hovenkamp, Platform Monopoly, supra note 279, at 1961.
400 Id.
401 See DEVLIN, supra note 10, at 281-84; Franklin M. Fisher, Diagnosing Monopoly, 19 Q. REV. ECON. & BUS. 7, 16
(1979) (“By focusing on whether products are in or out of the market, one converts a necessarily continuous question
into a question of yes or no.”).
402 138 S. Ct. 2274 (2018).
403 JAMES BESSEN, THE NEW GOLIATHS: HOW CORPORATIONS USE SOFTWARE TO DOMINATE INDUSTRIES, KILL
INNOVATION, AND UNDERMINE REGULATION 157 (2022); Lina Khan, The Supreme Court Case That Could Give Tech
Giants More Power, N.Y. TIMES (Mar. 2, 2018), https://www.nytimes.com/2018/03/02/opinion/the-supreme-court-
case-that-could-give-tech-giants-more-power.html; but see Tim Wu, The American Express Opinion, the Rule of
Reason, and Tech Platforms, 7 J. ANTITRUST ENF’T 117 (2019) (arguing that Amex’s holding is narrow and that the
decision is unlikely to impede antitrust enforcement against major tech platforms).
404 Letter from Fiona M. Scott Morton, et al., to Sen. Amy Klobuchar & Sen. Charles Grassley 1 (July 7, 2022),
https://som.yale.edu/sites/default/files/2022-07/AICOA-Final-revised.pdf (“[S. 2992’s] approach is carefully targeted
in that its prohibitions apply only to platforms deemed ‘critical trading partners’—meaning they have the power to
deprive business users of access to customers or access to inputs necessary for those users to run their businesses. The
result is that [S. 2992’s] restrictions apply to the platforms whose market positions confer undue gatekeeping power,
and no others.”).
405 Monika Schnitzer, et al., International Coherence in Digital Platform Regulation: An Economic Perspective on the
US and EU Proposals, YALE TOBIN CTR. FOR ECON. POLICY 9 (Aug. 9, 2021), https://tobin.yale.edu/sites/
default/files/Coherence%20in%20Digital%20Platform%20Regulation.pdf; see also Reining in Dominant Digital
Platforms: Restoring Competition to Our Digital Markets, Hearing Before the Subcomm. on Competition Policy,
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governing assessments of the “critical trading partner” standard would thus have to be fleshed out
in practice, if Congress were to enact legislation employing that concept.406
The use of the “critical trading partner” language instead of a market-power requirement is not
inherent to the designated-platform approach. In empowering a regulator to designate platforms
for special competition regulation, Congress could consider limiting designations to firms that
possess market power.
In the 117th Congress, S. 1074 would have taken that approach.407 The bill would have imposed
special merger rules on “dominant digital firms”—a term defined to mean companies that provide
online services and possess “dominant market power” in any market related to such services.408
Under the legislation, the FTC would have been empowered to designate companies as “dominant
digital firms” based on their possession of “dominant market power” and several other factors,
including network effects, use of exclusivity agreements, and vertical integration.409
In linking platform designation and market power, Congress could address some of the concerns
discussed above by dispensing with certain elements of market-power doctrine. For example,
Congress could provide that market definition is not necessary to establish market power or
abrogate specific decisions like Amex. One general antitrust bill in the 117th Congress would
have made both of those changes.410
Besides these issues involving designation criteria, the designated-platform approach implicates
the broader question of whether the Big Tech firms (and any other designated firms) are
sufficiently similar to warrant categorical regulatory treatment. As discussed, some commentators
have argued that Big Tech markets share important structural similarities that justify a consistent
regulatory response, while others have emphasized the differences between those markets.411 For
proponents of new competition regulations, that issue may be the central question that determines
the choice between the designated-platform approach and market-specific regulation.

Antitrust and Consumer Rights of the S. Comm. on the Judiciary (Mar. 7, 2023) (testimony of Daniel Francis, Assistant
Professor of Law, New York University School of Law at 85), https://www.judiciary.senate.gov/imo/media/doc/2023-
03-07%20-%20Testimony%20-%20Francis.pdf [hereinafter “Francis Testimony”] (arguing that the definition of
“critical trading partner” in the American Innovation and Choice Online Act was “strikingly broad and vague,” and that
it “appears to encompass any business that offers a desirable means of reaching customers for even a single business
user”).
406 One commentator has proposed a potentially similar test for identifying dominant platforms without resorting to
traditional market-power analysis. The relevant proposal would subject platforms to special competition regulations
based on an assessment of their “cost of exclusion”—a concept that measures the costs to an individual or business of
being excluded from a platform. HAROLD FELD, ROOSEVELT INST., THE CASE FOR THE DIGITAL PLATFORM ACT: MARKET
STRUCTURE AND REGULATION OF DIGITAL PLATFORMS 41-47 (May 8, 2019), https://rooseveltinstitute.org/wp-
content/uploads/2020/07/RI-Case-for-the-Digital-Platform-Act-201905.pdf. For a discussion of the mathematics
involved in calculating a firm’s “cost of exclusion,” see id. at 43-44.
407 Trust-Busting for the Twenty-First Century Act, S. 1074, 117th Cong. § 4 (2021).
408 Id.
409 Id.
410 Competition and Antitrust Law Enforcement Reform Act of 2021, S. 225, 117th Cong. §§ 9, 13 (2021); see also
DEVLIN, supra note 10, at 282 (calling for a reduced role for market definition in antitrust doctrine); HJC REPORT,
supra note 11, at 399 (arguing that Congress should adopt legislation overriding Amex and providing that market
definition is not required to prove an antitrust violation). For a defense of market definition, see Gregory J. Werden,
Why (Ever) Define Markets? An Answer to Professor Kaplow, 78 ANTITRUST L.J. 729 (2013). For a defense of the
Supreme Court’s Amex decision, see Geoffrey A. Manne, In Defence of the Supreme Court’s “Single Market”
Definition in Ohio v. American Express, 7 J. ANTITRUST ENFORCEMENT 104 (2019).
411 See supra “Market Structure and the Efficacy of Ex Post Adjudication.”
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Market-Specific Regulation
Some proposals for sectoral competition regulation rely on a more targeted strategy than the
designated-platform approach. Instead of applying the same set of regulations to designated firms
operating across a range of different tech markets, policymakers could adopt regulations tailored
to individual markets. In the 117th Congress, lawmakers introduced bills targeting two industries:
app stores and digital advertising.412
The Open App Markets Act (OAMA) would have established competition regulations for large
app stores.413 Among other things, the legislation would have prohibited operators of covered app
stores from tying their app stores to their payment processors, preferencing their own apps in
search results, and using nonpublic information derived from third-party apps to compete with
those apps.414 The bill’s requirements are discussed in greater detail in “Ex Ante Conduct Rules”
infra.
The Competition and Transparency in Digital Advertising Act would have imposed
structural-separation requirements and conduct rules on certain digital-advertising platforms.415
The legislation would have prohibited firms with more than $20 billion in annual
digital-advertising revenue from owning platforms that operate in more than one of the key nodes
in the ad-tech supply chain (ad exchanges, sell-side brokerages, and buy-side brokerages).416 It
also would have required firms with more than $5 billion in annual digital-advertising revenue to
abide by customer-protection rules involving best execution, transparency, and conflicts of
interest.417
Choice of Enforcers
A new regulatory regime for large tech platforms would require the selection of a regulator.
Several options are available. The designated-platform bills discussed above would have
empowered the DOJ and FTC to designate firms for special regulation.418 One of those bills—
which included interoperability and data-portability mandates—would have granted the FTC
rulemaking authority to develop standards implementing the relevant requirements.419 The others
would have given enforcement authority to the DOJ and FTC, but did not include explicit grants

412 Competition and Transparency in Digital Advertising Act, S. 4258, 117th Cong. (2022); Open App Markets Act, S.
2710, 117th Cong. (2022) (Reported Version); Competition and Transparency in Digital Advertising Act, H.R. 7839,
117th Cong. (2022); Open App Markets Act, H.R. 7030, 117th Cong. (2022); Open App Markets Act, H.R. 5017,
117th Cong. (2021).
413 S. 2710; H.R. 7030; H.R. 5017.
414 S. 2710 § 3; H.R. 7030 § 3; H.R. 5017 § 3.
415 S. 4258; H.R. 7839.
416 S. 4258 § 2; H.R. 7839 § 2. As discussed in supra “Digital Advertising,” the DOJ has filed a monopolization lawsuit
seeking to compel Google to divest some of its ad-tech businesses.
417 S. 4258 § 2; H.R. 7839 § 2.
418 American Innovation and Choice Online Act, S. 2992, 117th Cong. § 3(d) (2022) (Reported Version); Platform
Competition and Opportunity Act of 2021, S. 3197, 117th Cong. § 4 (2021); ACCESS Act of 2021, H.R. 3849, 117th
Cong. § 6 (2021); Platform Competition and Opportunity Act of 2021, H.R. 3826, 117th Cong. § 4 (2021); Ending
Platform Monopolies Act, H.R. 3825, 117th Cong. § 6 (2021); American Innovation and Choice Online Act, H.R.
3816, 117th Cong. § 2(d) (2021) (Reported Version).
419 H.R. 3849 § 6(c).
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of rulemaking power.420 Some of the bills also would have given enforcement authority to state
attorneys general.421
Some commentators have endorsed an alternative approach involving the creation of a new
specialist regulator for large digital platforms.422 In certain proposals, this regulator would be an
entirely new agency,423 while others would establish a new branch with special powers within an
existing antitrust authority.424 In the 117th Congress, the Digital Platform Commission Act would
have taken the former approach and created a new Federal Digital Platform Commission tasked
with regulating “systemically important digital platforms.”425
Reform Proposals
With the conceptual ground cleared, this final section of the report discusses the substance of
various proposals to reform the competition laws governing Big Tech platforms. The proposals
fall into five categories: (1) ex ante conduct rules, (2) structural separation and line-of-business
restrictions, (3) special merger rules, (4) interoperability and data-portability mandates, and
(5) changes to general antitrust doctrine.
Ex Ante Conduct Rules
As discussed, some commentators and legislators have advocated the adoption of prophylactic
conduct rules for Big Tech platforms, which would supplement general antitrust law.426 This
subsection reviews several of these proposals for ex ante competition regulations.
Self-Preferencing / Non-Discrimination Rules
The ability of large digital platforms to preference their own offerings is a recurring concern in
debates over antitrust reform. As discussed, several of the Big Tech firms have been accused of
engaging in various forms of self-preferencing. Google has allegedly favored its own verticals in
general search results, its own app store and apps through its control of Android, and its own
ad-tech businesses through its presence in multiple segments of the ad-tech market.427 Apple has
likewise been accused of preferencing its own apps and app store,428 while Amazon has allegedly
privileged its own private-label products and products that use its logistics service.429

420 S. 2992; S. 3197; H.R. 3826; H.R. 3825; H.R. 3816.
421 S. 2992 § 2(c)(1)(C); S. 3197 § 5(a)(3); H.R. 3826 § 5(a); H.R. 3816 § 2(h)(1)(C). Some of the bills also would have
created private rights of action. S. 3197 § 7; H.R. 3826 § 7; H.R. 3816 § 6.
422 STIGLER REPORT, supra note 333, at 104-06; UK DIGITAL COMPETITION REPORT, supra note 333, at 8.
423 Rogerson & Shelanski, supra note 342, at 1916; STIGLER REPORT, supra note 333, at 104-06.
424 ACCC Report, supra note 162, at 31; see also UK DIGITAL COMPETITION REPORT, supra note 333, at 10 (noting both
options); FELD, supra note 406, at 188-95 (discussing the advantages and disadvantages of creating a new
digital-platform regulator).
425 Digital Platform Commission Act of 2022, S. 4201, 117th Cong. (2022); Digital Platform Commission Act of 2022,
H.R. 7858, 117th Cong. (2022).
426 S. 2992; H.R. 3816; OECD REGULATION REPORT, supra note 340, at 9-15; UK DIGITAL COMPETITION REPORT, supra
note 333, at 62-63.
427 See supra “Google.”
428 See supra “Apple.”
429 See supra “Amazon.”
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The primary concern with this type of conduct involves monopoly leveraging.430 As discussed,
leveraging theories of harm can take two forms. Offensive leveraging occurs when a firm
attempts to use monopoly power in a primary market to extract additional profits from a
secondary market.431 By contrast, defensive leveraging involves the use of monopoly power to
gain an advantage in a secondary market so as to preserve a primary market monopoly—for
example, by eliminating competitive threats that might emerge from the secondary market.432
Defensive leveraging may be a viable theory of harm under existing monopolization law.433
Offensive-leveraging claims, however, cannot succeed under Section 2 absent evidence that a
defendant had a dangerous probability of monopolizing a secondary market; mere harm to
competition in the secondary market is not sufficient.434
For some of the self-preferencing allegations against Big Tech firms, these limitations may
preclude monopolization claims.435 It may be unlikely, for example, that Amazon will achieve
monopoly power over most of the products that it sells on its marketplace. As a result, it would be
difficult to challenge the preferential display of those products under an offensive-leveraging
theory.436 This type of alleged favoritism may also be a weak foundation for a
defensive-leveraging or monopoly-maintenance case; it is not clear that Amazon’s alleged
elevation of inferior products helps it maintain a putative e-commerce monopoly.
Similarly, the case law governing unilateral refusals to deal is not an attractive vehicle for
challenging platform self-preferencing. A platform operator’s favorable treatment of its own
verticals relative to rivals that use its platform is typically less harmful to rivals than an outright
refusal of access.437 Because antitrust imposes access duties only in a narrow set of
circumstances, many forms of self-preferencing are unlikely to constitute unlawful refusals to
deal.438

430 See generally Todd, supra note 249.
431 GIUSEPPE COLANGELO, INT’L CTR. FOR L. & ECON., ANTITRUST UNCHAINED: THE EU’S CASE AGAINST SELF-
PREFERENCING (2022), https://laweconcenter.org/resources/antitrust-unchained-the-eus-case-against-self-
preferencing/?doing_wp_cron=1675175836.8782548904418945312500.
432 Robin Cooper Feldman, Defensive Leveraging in Antitrust, 87 GEO. L.J. 2079, 2080 (1999); Matthew Levinton,
Defensive Leveraging as Monopolization, AM. BAR ASS’N (June 22, 2022), https://www.americanbar.org/groups/
antitrust_law/resources/newsletters/defensive-leveraging-as-monopolization.
433 See United States v. Microsoft, 253 F.3d 34, 67 (D.C. Cir. 2001) (per curiam).
434 Verizon Commc’ns Inc. v. L. Offs. of Curtis V. Trinko, LLP, 540 U.S. 398, 410 n.4 (2004); see also Levinton,
supra note 432.
435 See GREGORY J. WERDEN, THE FOUNDATIONS OF ANTITRUST: EVENTS, IDEAS, AND DOCTRINES 355 (2020) (discussing
leveraging claims under U.S. law and concluding that “[s]elf-preferencing by digital platform monopolists will be
minimally constrained in the United States unless Congress creates a new regulatory structure for digital platforms”).
436 Herbert J. Hovenkamp, Monopolizing and the Sherman Act 32 (Penn. Carey L. Sch., Research Paper, No. 2769,
2022), https://scholarship.law.upenn.edu/cgi/viewcontent.cgi?article=3772&context=faculty_scholarship.
437 Hovenkamp, Antitrust Duty to Deal, supra note 359, at 1546.
438 Trinko, 540 U.S. at 409. Refusal-to-deal doctrine is discussed in greater detail in supra “Refusals to Deal.” The
essential-facilities doctrine is also unlikely to preclude many forms of platform self-preferencing for a variety of
reasons, even if that doctrine remains good law. For an overview of the difficulties facing an essential-facilities
challenge to “search bias,” for example, see Marina Lao, Search, Essential Facilities, and the Antitrust Duty to Deal,
11 NW. J. TECH. & INTELL. PROP. 275, 298-304 (2013).
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In the 117th Congress, the American Innovation and Choice Online Act (AICOA) would have
responded to these doctrinal difficulties by prohibiting covered platform operators from
preferencing their own products and services in certain circumstances.439
Different versions of the legislation structured the prohibition differently.
The Senate Judiciary Committee reported a version of the AICOA that would have prohibited
covered platform operators from preferencing their own products “in a manner that would
materially harm competition.”440
The House Judiciary Committee, by contrast, reported a version of the bill that would have
prohibited platform self-preferencing but granted defendants certain competition-related
affirmative defenses.441 In particular, the reported House bill would have allowed defendants to
avoid liability if they established by clear and convincing evidence that their conduct would
(1) not harm “the competitive process by restricting or impeding legitimate activity by business
users,” or (2) increase “consumer welfare.”442
These competing approaches raise a central issue in the debate over conduct rules for Big Tech
platforms: the role of business justifications. As discussed, antitrust has developed a general
burden-shifting framework that often allows defendants to rebut a prima facie case of competitive
harm by establishing procompetitive justifications for their conduct.443 The opportunity to offer
such arguments likely reduces the incidence of false positives.444 One of the primary motivations
for ex ante conduct rules, however, is a desire to avoid the delays and expense that accompany
this type of fact-intensive analysis.445 The proper framework for evaluating business justifications
thus implicates a key trade-off facing proponents of competition regulation.
The AICOA’s resolution of that trade-off was not entirely clear. As discussed, different versions
of the bill employed different approaches to the issue of competitive harm. The self-preferencing
prohibition in the reported Senate bill would have made “material harm to competition” an
element of the government’s case-in-chief.446 The reported House bill, by contrast, offered
competition-related affirmative defenses subject to a clear-and-convincing-evidence standard.447
That difference might suggest that the reported Senate bill took a more defendant-friendly
approach than the reported House bill. Some lawmakers and commentators, however, argued that

439 American Innovation and Choice Online Act, S. 2992, 117th Cong. § 3(a)(1) (2022) (Reported Version); American
Innovation and Choice Online Act, H.R. 3816, 117th Cong. § 2(a)(1) (2021) (Reported Version). The OAMA included
a more limited prohibition of self-preferencing related to app-store search results. The bill would have prohibited
covered firms from “unreasonably preferencing or ranking” their own apps in search results. Open App Markets Act, S.
2710, 117th Cong. § 3(e)(1) (2022) (Reported Version); Open App Markets Act, H.R. 7030, 117th Cong. § 3(e)(1)
(2021); Open App Markets Act, H.R. 5017, 117th Cong. § 3(e)(1) (2021).
440 S. 2992 § 3(a)(1).
441 H.R. 3816 §§ 2(a)(1), (c)(1), (c)(3).
442 Id. §§ 2(c)(1), (c)(3). The bills offered separate affirmative defenses related to user privacy, data security, and
compliance with other laws. S. 2992 § 3(b)(1); H.R. 3816 § 2(c)(2). The reported Senate version of the bill also
provided an affirmative defense related to the maintenance or enhancement of a platform’s “core functionality.” S.
2992 § 3(b)(1)(C).
443 See, e.g., Ohio v. Am. Express Co., 138 S. Ct. 2274, 2284 (2018) (describing the framework in a Section 1 case);
Viamedia, Inc. v. Comcast Corp., 951 F.3d 429, 463-64 (7th Cir. 2020) (describing the framework in a Section 2 case).
444 See, e.g., Crane, supra note 343, at 55.
445 See, e.g., Chopra & Khan, supra note 343, at 360.
446 S. 2992 § 3(a)(1).
447 H.R. 3816 §§ 2(c)(1), (c)(3).
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the meaning of the “materially harm competition” standard in the Senate-reported bill was
unclear.448 Among other things, they highlighted the novelty of the standard’s materiality
language, the absence of a market-power requirement, and the bill’s omission of an explicit
consumer-welfare defense.449
Those factors made it difficult to predict the type of framework a court might have adopted in
applying the “materially harm competition” standard. In particular, it appeared unclear whether
that language was intended to broaden the types of competitive harm that antitrust has
traditionally recognized.450
This issue overlapped with questions about the relationship between the “materially harm
competition” standard and antitrust’s existing analytical tools. For example, if that standard was
intended to implement something similar to traditional rule-of-reason burden shifting—which
allows defendants to offer procompetitive justifications for their conduct—then litigation under
the AICOA may have been nearly as costly and time-consuming as Sherman Act lawsuits.451 On
the other hand, an interpretation of the bill that did not permit consumer-welfare or efficiency
justifications would have represented a departure from the prevailing framework for assessing
competitive harm.452 If the AICOA had been enacted, courts may have been reluctant to move
away from these existing analytical tools without clearer legislative direction.

448 Hovenkamp, Gatekeeper Competition Policy, supra note 394, at 24 (arguing that the meaning of the “materially
harm competition” standard was unclear and that “[i]f the AICOA is redrafted, this provision more than any other
needs clarification”); A. Douglas Melamed, Why I Think Congress Should Not Enact the American Innovation and
Choice Online Act, COMPETITION POLICY INT’L (June 19, 2022), https://www.competitionpolicyinternational.com/why-
i-think-congress-should-not-enact-the-american-innovation-and-choice-online-act/ (arguing that the meaning of the
“materially harm competition” standard was not clear); ABA Letter, supra note 391, at 5, 9-11 (similar); Transcript of
Markup of S. 2992 at 53 (Jan. 20, 2022) (on file with author) [hereinafter “S. 2992 Markup Transcript”] (Sen. Thom
Tillis) (“It’s not clear how existing competitor or competition jurisprudence would support or be changed by [S. 2992].
The purpose of competition law is to eliminate harm to consumers not to pick winners and losers. I’m also aware of the
spirited debate [over] whether decades of antitrust law based on [the] consumer-welfare standard should be put in the
burn pit. I’m open to having [a] separate discussion about potential changes to that standard and I hope that we will.
But as it stands in relation to this bill, what standard will enforcers look to[?] What about amendments [that] would
insert [the] consumer welfare standard back into the definition of material harm to competition?”).
449 Melamed, supra note 448; ABA Letter, supra note 391, at 6; S. 2992 Markup Transcript, supra note 448, at 53.
450 Francis Testimony, supra note 405, at 55 (“‘[H]arm to competition’ is just not a phrase with a single self-executing
meaning. It could be interpreted to mean welfare harm in a manner we would associate with traditional antitrust; or it
could be interpreted to mean ‘injury to rivals[.]’”) (emphasis in original); Hovenkamp, Gatekeeper Competition Policy,
supra note 394, at 23-24 (“If competition is defined in an economically sensible way to refer to reduced market output
and higher prices, then the statute might end up limiting its reach to conduct posing a realistic threat of competitive
harm. If it means something else, such as merely injuring a rival or placing it at a disadvantage on that particular
platform as opposed to the market as a whole, then it could end up doing a great deal of harm.”).
451 See Francis, supra note 48, at 823-24 (arguing that antitrust rules allowing defendants to offer justifications for
challenged conduct would be “unlikely to lighten the adjudicative load much”). Under this reading of the bill, the
self-preferencing prohibition still would have modified existing law by substituting the designation criteria discussed
earlier in this report for a market-power requirement. The prohibition also would have potentially covered conduct that
currently escapes liability because of the limitations on monopoly-leveraging and refusal-to-deal claims discussed in
this section.
452 Ohio v. Am. Express Co., 138 S. Ct. 2274, 2284 (2018); United States v. Microsoft Corp., 253 F.3d 34, 59 (D.C.
Cir. 2001) (per curiam); Schnitzer, et al., supra note 405, at 20 (interpreting the AICOA to not allow platforms to
defend challenged conduct on efficiency grounds, “as might be possible in a standard antitrust case”). The absence of
consumer-welfare and efficiency justifications would, however, be consistent with some conceptions of “competition”
that prevailed in earlier periods of antitrust history and with the stated aims of the recent Neo-Brandeisian movement.
See supra “The Goals of Antitrust” & “Substantive Antitrust Doctrine.”
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Given the potential expansiveness of a general self-preferencing prohibition,453 these issues
involving competitive harm and business justification would likely represent key questions for
any similar legislative efforts.454 Those issues also underscore that the distinction between
adjudicative and regulatory approaches to competition issues in the tech sector may be more of a
continuum than an either/or question. Unless ex ante rules entail categorical prohibitions based on
the form of challenged conduct, the competitive-effects analysis that characterizes modern
antitrust adjudication would likely play some role in a new regulatory regime.
Tying
Besides its self-preferencing prohibition, the AICOA would have barred covered platform
operators from tying access to or preferred placement on their platforms to the purchase or use of
other products or services.455 The OAMA included a narrower tying provision. The bill would
have prohibited covered firms from conditioning access to their app stores on the use of their
payment processors.456
As discussed, existing antitrust doctrine prohibits tying in certain circumstances. Under current
law, a plaintiff can prevail on a tying claim by showing that:
1. The defendant offered two distinct products;
2. The defendant conditioned the sale of one product (the tying product) on the
purchase of the other product (the tied product);
3. The defendant possessed sufficient economic power in the tying product market
to coerce purchasers into acceptance of the tied product; and
4. The defendant’s conduct affected a “not insubstantial” amount of interstate
commerce in the tied product.457
Some courts have also required plaintiffs to demonstrate that a tying arrangement had
anticompetitive effects in the tied product market.458
Unlike this test, neither the AICOA nor the OAMA contained explicit market-power
requirements. Instead, as discussed, the AICOA used certain quantitative criteria and a “critical
trading partner” standard to identify the platforms that would be subject to its prohibitions.459 The
OAMA, in contrast, employed only a quantitative threshold. The bill would have applied to
companies that control app stores with more than 50 million U.S. users.460

453 See Hovenkamp, Proposed Antitrust Reforms, supra note 391, at 18 (noting the ubiquity of self-preferencing by
vertically integrated firms); Randy Picker, How Would the Big Tech Self-Preferencing Bill Affect Users?, PROMARKET
(June 16, 2022), https://www.promarket.org/2022/06/16/how-would-the-big-tech-self-preferencing-bill-affect-users/
(reviewing possible implications of a general self-preferencing prohibition for Big Tech platforms).
454 See D. Daniel Sokol, A Framework for Digital Platform Regulation, 17 COMPETITION L. INT’L 95, 102 (2021)
(discussing the role that defenses and competitive-effects analysis may play in a regulatory regime for digital
platforms).
455 American Innovation and Choice Online Act, S. 2992, 117th Cong. § 3(a)(5) (2022) (Reported Version); American
Innovation and Choice Online Act, H.R. 3816, 117th Cong. § 2(b)(2) (2021) (Reported Version).
456 Open App Markets Act, S. 2710, 117th Cong. § 3(a)(1) (2022) (Reported Version); Open App Markets Act, H.R.
7030, 117th Cong. § 3(a)(1) (2021); Open App Markets Act, H.R. 5017, 117th Cong. § 3(a)(1) (2021).
457 HOVENKAMP, supra note 70, at 435 (summarizing the test employed by most federal circuit courts of appeals).
458 Id. at 435-36.
459 See supra “The Designated-Platform Approach.”
460 S. 2710 § 2(3); H.R. 7030 § 2(3); H.R. 5017 § 2(3).
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Both bills also would have departed from the tying test employed by some federal courts of
appeals that requires proof of anticompetitive effects.461 The AICOA’s tying prohibition would
have instead offered defendants certain competition-related affirmative defenses.462 The OAMA’s
enforcement would not have involved competitive-effects analysis.463
In addition to ties involving app stores and payment processors, the AICOA’s tying provision
potentially would have implicated several of the other practices discussed above, including some
of Google’s conduct in ad-tech markets and the link between favorable placement on Amazon’s
marketplace and use of Amazon’s logistics service.464
Interoperability and Data Access
Other proposals involve the ability of business users to interoperate with and access data they
generate on covered platforms.
The AICOA, for example, included an interoperability provision that would have prohibited
covered platform operators from restricting or impeding the ability of business users to
interoperate with features that are available to the operator’s own products or services.465 Among
other conduct, the prohibition may have been directed at Facebook’s alleged refusal to allow
certain app developers to access Facebook Platform and Apple’s alleged refusal to allow
developers to access some APIs and device functionalities that are available to Apple’s apps.466
The OAMA also contained interoperability requirements. The bill would have required covered
companies to allow users of their operating systems to install third-party apps and app stores
through means other than the covered companies’ app stores.467 It also would have mandated that
covered firms provide developers with access to operating-system interfaces, development
information, and hardware and software features on terms that are functionally equivalent to those
that covered firms offer to their own apps.468
The AICOA’s data-access provision would have prohibited covered platform operators from
restricting or impeding a business user from accessing or transferring data generated by the user’s
activities on a covered platform.469
Interoperability and data-portability issues are discussed in greater detail in “Interoperability &
Data Portability” infra.

461 See, e.g., Kaufman v. Time Warner, 836 F.3d 137, 141 (2d Cir. 2016); Amey, Inc. v. Gulf Abstract & Title Inc., 758
F.2d 1486, 1503 (11th Cir. 1985); Driskill v. Dallas Cowboys Football Club, Inc., 498 F.2d 321, 323 (5th Cir. 1974).
462 American Innovation and Choice Online Act, S. 2992, 117th Cong. § 3(b)(2)(A) (2022) (Reported Version);
American Innovation and Choice Online Act, H.R. 3816, 117th Cong. §§ 2(c)(1), (c)(3) (2021) (Reported Version).
463 S. 2710; H.R. 7030; H.R. 5017.
464 See supra “Google” & “Amazon.” The tying provision in the reported Senate version of the AICOA would not have
barred ties involving products that are “part of or intrinsic to” a covered platform. S. 2992 § 3(a)(5). Some
commentators have argued that this exception was vague and would likely be the subject of litigation. See Francis
Testimony, supra note 405, at 68; ABA Letter, supra note 391, at 5-6.
465 S. 2992 § 3(a)(4); H.R. 3816 § 2(b)(1).
466 See supra “Meta Platforms” & “Apple.”
467 S. 2710 § 3(d)(2); H.R. 7030 § 3(d)(2); H.R. 5017 § 3(d)(2).
468 S. 2710 § 3(f); H.R. 7030 § 3(f); H.R. 5017 § 3(f).
469 S. 2992 § 3(a)(7); H.R. 3816 § 2(b)(4).
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Use of Nonpublic User Data
As discussed, some Big Tech firms have been accused of using their access to user data to
identify and imitate popular offerings. Amazon, for example, has allegedly used nonpublic user
data to find profitable opportunities for its own private-label business.470 Apple has similarly been
accused of using competitively sensitive information to replicate fast-growing apps and integrate
certain functionalities into iOS.471
Some proposals would prohibit this conduct. Both the AICOA and OAMA included provisions
that would have barred covered companies from using nonpublic data from dependent businesses
to support their own offerings.472
This type of prohibition has been debated. Some commentators have argued that a platform
operator’s imitation of rival products typically increases static efficiency by stimulating
competition and lowering prices.473 Others have argued that a ban on the use of nonpublic data by
platform operators would boost dynamic efficiency by protecting the incentives of other
businesses to innovate.474
Most-Favored-Nation and Anti-Steering Policies
Another general category of proposals involves platform restrictions of the activities of business
users in other transaction venues.
The reported House version of the AICOA would have prohibited covered platform operators
from restricting a business user’s pricing of its products or services or its communications on a
covered platform regarding other transaction options.475 Similarly, the OAMA would have barred
covered companies from restricting developers from communicating with users about “legitimate
business offers,” including pricing terms and product or service offerings.476
Some of the pricing restrictions targeted by the House version of the AICOA include
most-favored-nation clauses (MFNs), which prohibit a platform’s business users from offering
lower prices on rival platforms.477 Platform MFNs may make it difficult for rivals to compete
with a dominant platform by charging lower commissions, because such clauses prevent business
users from passing along those savings to consumers.478
The primary procompetitive benefit proffered in defense of MFNs involves concerns about
free-riding. The basic worry is that, absent an MFN, consumers will use a highly functional
platform to search for and compare products, but then make their purchases on a different

470 See supra “Amazon.”
471 See supra “Apple.”
472 S. 2992 § 3(a)(6); H.R. 3816 § 2(b)(3); S. 2710 § 3(c); H.R. 7030 § 3(c); H.R. 5017 § 3(c).
473 Francis, supra note 48, at 832; Hovenkamp, Platform Monopoly, supra note 279, at 2015; Sokol, supra note 454, at
102.
474 Andre Hagiu, Tat-How Teh & Julian Wright, Should Platforms Be Allowed to Sell on Their Own Marketplaces?, 53
RAND. J. ECON. 297, 32 (2022).
475 H.R. 3816 § 2(b)(6), (b)(8).
476 S. 2710 § 3(b); H.R. 7030 § 3(b); H.R. 5017 § 3(b).
477 Baker & Scott Morton, supra note 262, at 2181. As discussed, Amazon has faced a lawsuit challenging its pricing
restrictions, though the nature of the relevant policies was disputed. See supra “Amazon.”
478 Baker & Scott Morton, supra note 262, at 2195 n.82. Platform MFNs may also facilitate collusion among sellers on
a platform. Id. at 2182.
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low-cost platform.479 Under those conditions, platforms may lack incentives to invest in
expensive site features like an attractive design or effective comparison tools, even though those
features benefit consumers.480
The literature has distinguished between “narrow” platform MFNs (which restrict a seller’s prices
only on the seller’s own website) and “wide” platform MFNs (which restrict a seller’s prices on
all other platforms).481 Some theoretical analyses have concluded that narrow MFNs are more
likely to be procompetitive than wide MFNs.482
The reported House version of the AICOA would have prohibited both narrow and wide platform
MFNs.483 Challenged restrictions would have escaped liability, however, if a platform operator
established by clear and convincing evidence that its conduct would (1) not harm “the
competitive process by restricting or impeding legitimate activity by business users,” or
(2) increase “consumer welfare.”484
App Preinstallation
The AICOA and OAMA also included provisions prohibiting covered firms from restricting or
impeding the uninstallation of preinstalled apps or changing default settings that steer users to a
covered firm’s own products or services.485
These prohibitions appeared to be directed at concerns that Google and Apple have leveraged
control of their operating systems to favor their own apps and app stores.486 Though the bills did
not explicitly prohibit the preinstallation of a covered firm’s proprietary apps, commentators have
debated whether such preinstallation would run afoul of the AICOA’s general self-preferencing
prohibition.487
Structural Separation and Line-of-Business Restrictions
Several of the proposed rules discussed above respond to concerns that Big Tech firms face
conflicts of interest when they operate both a digital platform and vertically related businesses
that compete with platform users. The proposals sought to address those concerns by prohibiting
specific categories of allegedly problematic conduct. One possible downside of this approach
involves administrability.

479 Id. at 2183-84.
480 Id. at 2184.
481 Schnitzer, et al., supra note 405, at 18 n.12.
482 Baker & Scott Morton, supra note 262, at 2184 n.23 (citing examples).
483 American Innovation and Choice Online Act, H.R. 3816, 117th Cong. § 2(b)(8) (2021) (Reported Version).
484 Id. §§ 2(c)(1), (c)(3).
485 American Innovation and Choice Online Act, S. 2992, 117th Cong. § 3(a)(8) (2022) (Reported Version); H.R. 3816
§ 2(b)(5); Open App Markets Act, S. 2710, 117th Cong. § 3(d)(1), (d)(3) (2022) (Reported Version); Open App
Markets Act, H.R. 7030, 117th Cong. § 3(d)(1), (d)(3) (2021); Open App Markets Act, H.R. 5017, 117th Cong.
§ 3(d)(1), (d)(3) (2021).
486 See supra “Google” & “Apple.”
487 Compare Picker, supra note 453 (arguing that the AICOA’s self-preferencing prohibition may prohibit app
preinstallation), with Hal Singer, Rep. Cicilline’s Nondiscrimination Bill Would Offer a Lifeline to Independent App
Developers, PROMARKET (July 2, 2021), https://www.promarket.org/2021/07/02/antitrust-self-preferencing-
preinstallation-app-developers-apple/ (arguing that the AICOA would not prohibit app preinstallation).
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The worry is twofold. First, conduct rules require regulators to continuously monitor the behavior
of covered firms.488 Second, as discussed, the availability of affirmative defenses means that rule
enforcement may entail some of the same issues of cost and timeliness that have led to
dissatisfaction with the existing antitrust framework.489
Based on these potential difficulties, some commentators have argued that structural restrictions
have important advantages over behavioral rules.490 Such restrictions can take two general forms.
Structural regulation could involve total separation, meaning firms would be prohibited from
owning both a covered platform and a business that operates on that platform.491 Alternatively,
regulations could mandate partial or functional separation, whereby firms would be required to
house a covered platform and vertically related businesses in separate legal entities.492
There is precedent for these types of structural regulations, including in the railroad, banking, and
telecommunications industries.493
In the 117th Congress, H.R. 3825 would have adopted a separations regime for covered platform
operators.494 The bill would have prohibited covered platform operators from owning, controlling,
or having a beneficial interest in a “line of business” that:
 utilizes the covered platform for the sale or provision of products or services;
 offers a product or service that the covered platform requires business users to
purchase or utilize as a condition of accessing or receiving preferred placement
on the platform; or
 gives rise to a “conflict of interest.”495
The bill would have provided that “conflicts of interest” arise when a platform operator’s
ownership or control of another “line of business” creates the incentive and ability for its platform
to (1) advantage the platform operator’s products or services over those of competitors, or
(2) exclude or disadvantage the products or services of competitors.496
These types of proposals have generated debate. Critics of separation requirements have argued
that a platform’s entry into new markets typically benefits consumers.497 For example, by selling
its own private-label products on its marketplace, Amazon may offer consumers low-cost

488 HJC REPORT, supra note 11, at 381; Khan, Platforms and Commerce, supra note 274, at 1036.
489 See, e.g., Francis, supra note 48, at 823-24.
490 HJC REPORT, supra note 11, at 381; Khan, Platforms and Commerce, supra note 274, at 1036; see also Rory Van
Loo, In Defense of Breakups: Administering a “Radical” Remedy, 105 CORNELL L. REV. 1955, 2007 (2020) (arguing
that breakups may be preferable to access remedies in certain circumstances).
491 Khan, Platforms and Commerce, supra note 274, at 1052.
492 Id.
493 Id. at 1037-43, 1045-51.
494 Ending Platform Monopolies Act, H.R. 3825, 117th Cong. (2021).
495 Id. § 2(a).
496 Id. § 2(b). In the 117th Congress, S. 1204 would have also imposed structural separation requirements on large
online marketplaces, exchanges, and search engines. Bust Up Big Tech Act, S. 1204, 117th Cong. § 2 (2021).
497 Hagiu, et al., supra note 474, at 319; Herbert J. Hovenkamp, The Looming Crisis in Antitrust Economics, 101 B.U.
L. REV. 489, 541 (2021) [hereinafter “Hovenkamp, Looming Crisis”]; Giuseppe Colangelo, Evaluating the Case for
Regulation of Digital Platforms, in GLOBAL ANTITRUST INSTITUTE REPORT ON THE DIGITAL ECONOMY 905 (2020);
Thomas A. Lambert, The Case Against Legislative Reform of U.S. Antitrust Doctrine 21-22 (Univ. of Mo. Sch. of L.
Legal Studies, Research Paper No. 2020-13, 2020), https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3598601;
Todd, supra note 249, at 524-25.
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alternatives to established brands.498 Integration into related business lines may also create
efficiencies.499 Apple and Google, for instance, may be well-positioned to produce apps and app
stores for their respective operating systems, as well as related devices like earphones and smart
watches.500
Separation requirements may also face line-drawing difficulties. The boundary between a covered
platform and separate services is not always clear.501 For example, Apple produces many apps and
functionalities—including a voice assistant (Siri), a camera app, and a payment system (Apple
Pay)—that are integrated with its iOS operating system to various degrees.502 Whether these
services would qualify as “lines of business” that are distinct from iOS may be uncertain; H.R.
3825 did not define that term. Because tech platforms regularly add new functionalities to their
primary services, some observers have argued that an absence of clarity surrounding permissible
activities may deter innovation and thereby harm consumers.503
Proponents of separation requirements have acknowledged these criticisms. In response, they
have argued that the innovation benefits of an equal playing field would likely outweigh any
losses in static efficiency that result from the elimination of a platform operator’s downward
pricing pressure in adjacent markets.504 In addition, advocates of separation rules contend that any
decreases in platform innovation caused by such rules must be weighed against likely increases in
innovation by platform users.505 The arguments in favor of broad separation requirements have
thus focused on innovation policy, in addition to the foreclosure concerns that sound in traditional
antitrust analysis.
Mergers & Acquisitions
Substantive Merger Law
Other proposals target Big Tech mergers. In the 117th Congress, H.R. 3826 would have
prohibited covered platform operators from acquiring other firms unless they could demonstrate
by clear and convincing evidence that a target does not:
 compete with the platform operator;

498 Hovenkamp, Looming Crisis, supra note 497, at 541 (“Many of the brands that compete with Amazon’s own brands
are sold by large firms, often at margins that are significantly higher than Amazon’s margins. . . . Forcibly separating
Amazon’s brands from the offerings of these companies will almost certainly reduce downward pricing pressure on
these national name brands, resulting in higher prices for consumers.”).
499 See, e.g., Todd, supra note 249, at 514-17.
500 Randy Picker, The House’s Recent Spate of Antitrust Bills Would Change Big Tech as We Know It, PROMARKET
(June 29, 2021), https://www.promarket.org/2021/06/29/house-antitrust-bills-big-tech-apple-preinstallation/.
501 Carl Shapiro, Protecting Competition in the American Economy: Merger Control, Tech Titans, Labor Markets, 33 J.
ECON. PERSPS. 69, 84 (2019); Hal Singer, Inside Tech’s “Kill Zone”: How to Deal With the Threat to Edge Innovation
Posed by Multi-Sided Platforms, PROMARKET (Nov. 21, 2018), https://www.promarket.org/2018/11/21/inside-tech-kill-
zone/.
502 Todd, supra note 249, at 536.
503 E.g., Rogerson & Shelanski, supra note 342, at 1934.
504 Khan, Platforms and Commerce, supra note 274, at 1085; see also Feng Zhu & Qihong Liu, Competing with
Complementors: An Empirical Look at Amazon.com, 39 STRATEGIC MGMT. J. 2168 (2018) (concluding that, while
Amazon’s entry into a new market typically reduces prices, it may also reduce the number of innovative products on
Amazon’s marketplace by discouraging participation by third-party sellers).
505 Khan, Platforms and Commerce, supra note 274, at 1085.
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 constitute “nascent or potential competition” for the platform operator;
 enhance or increase the platform operator’s market position with respect to
products or services offered on or directly related to a covered platform; or
 enhance or increase the platform operator’s ability to maintain its market position
with respect to products or services offered on or directly related to a covered
platform.506
The reported version of the bill included an amendment that would have exempted transactions of
less than $50 million from the prohibition.507
For transactions of $50 million or greater, then, the bill would have prohibited Big Tech firms
from engaging in horizontal mergers, mergers involving “nascent or potential” competitors, and
vertical and conglomerate mergers that enhance, increase, or help maintain their market positions
with respect to products or services “offered on or directly related” to a covered platform.
As drafted, the bill raised three issues. The first involved the legislation’s prohibition of
acquisitions involving “potential” competitors.508 As discussed, antitrust doctrine has recognized
two theories of harm in potential-competition cases: the elimination of perceived potential
competition and the elimination of actual potential competition.509 Courts have identified
prerequisites for both theories.510
The relationship between those prerequisites and H.R. 3826’s requirement that a Big Tech
platform show that a target firm is not a “potential” competitor may have generated complex legal
questions, if the bill had become law. For example, the bill could have been read to allow
platform operators to make such a showing by negating an element of both types of
potential-competition claims.511 That is not, however, the only interpretive option; the details
surrounding the relevant burden would have had to be fleshed out in practice. That the Supreme
Court has recognized only the perceived-potential-competition theory might have complicated
this inquiry.
The second issue concerned the bill’s prohibition of Big Tech acquisitions involving “nascent”
competitors.512 Commentators have offered different definitions of the concept of “nascent”
competition.513 In general, however, the term has been used to refer to new technologies with
uncertain prospects that nevertheless pose serious threats to an incumbent.514

506 Platform Competition and Opportunity Act of 2021, H.R. 3826, 117th Cong. § 2(b)(2) (2021). The bill would have
also excluded certain categories of transactions that are exempt from pre-merger filing requirements for reasons other
than their size. Id. § 2(b)(1).
507 Amendment to the Amendment in the Nature of a Substitute to H.R. 3826 Offered by Ms. Ross of North Carolina,
Markups, H.R. 3843, the Merger Filing Fee Modernization Act of 2021, et al., H. Comm. on the Judiciary, 117th Cong.
(June 24, 2021), https://docs.house.gov/meetings/JU/JU00/20210623/112818/BILLS-117-HR3826-R000305-Amdt-
1.pdf.
508 H.R. 3826 § 2(b)(2)(B).
509 See supra “Conglomerate Mergers.”
510 Id.
511 Under the bill, such efforts would be subject to a clear-and-convincing-evidence standard. H.R. 3826 § 2(b).
512 Id. § 2(b)(2)(B).
513 Yun, supra note 334, at 626 (“Amongst antitrust practitioners and scholars, various definitions have emerged for
nascent competition”); Hemphill & Wu, supra note 334, at 1881 (“Nascent competition means different things to
different people.”).
514 United States v. Microsoft Corp., 253 F.3d 34, 79 (D.C. Cir. 2001) (per curiam); Yun, supra note 334, at 626-27;
Hemphill & Wu, supra note 334, at 1886-88; Tracy J. Penfield & Molly Pallman, Looking Ahead: Nascent Competitor
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Despite posing such threats, acquisitions of “nascent” competitors may be difficult to challenge
under existing law. As discussed, to prevail under an actual-potential-competition theory, a
plaintiff must establish a “substantial likelihood” that a target firm would deconcentrate the
relevant market or produce other procompetitive benefits.515 In cases involving unproven or
developing technology, that burden could prove problematic for a plaintiff. H.R. 3826 was a
response to this doctrinal difficulty.516
While the bill thus sought to address an issue that has generated considerable attention, the
analytical framework that would govern inquiries into “nascent” competition remains unsettled.
There is little case law addressing issues of “nascent” competition in the merger context.517
Accordingly, H.R. 3826 would have leaned on the courts to develop standards for evaluating
whether a firm constituted a “nascent” competitor of a covered platform.
The third issue raised by H.R. 3826 involved the breadth of the provisions prohibiting mergers
that “enhance or increase” a platform operator’s market position or ability to maintain its market
position.518
By their terms, these prohibitions did not distinguish between procompetitive mergers and
anticompetitive mergers. As drafted, the bill thus appeared to prohibit mergers that “enhance or
increase” a Big Tech platform’s market position by improving the quality of its products or
services, even when the target company is not a competitor, potential competitor, or nascent
competitor of the platform. As a result, H.R. 3826 may have limited Big Tech platforms to
in-house development or licensing of complementary technologies; acquisitions of firms that
could enhance a platform’s core offerings would have likely been off-limits.
S. 1074—another bill in the 117th Congress—would have taken a similarly strict approach
toward Big Tech mergers.519 Among other things, S. 1074 would have prohibited companies
designated as “dominant digital firms” from engaging in acquisitions valued at more than
$1 million.520

Acquisition Challenges in the “TechLash” Era, ANTITRUST SOURCE 2 (June 2020),
https://www.americanbar.org/content/dam/aba/publishing/antitrust-magazine-online/2020/june-
2020/jun20_penfield_6_17f.pdf.
515 United States v. Marine Bancorporation, Inc., 418 U.S. 602, 633 (1974).
516 There is an ongoing debate within the antitrust community as to whether Section 2 of the Sherman Act provides a
more attractive vehicle for challenging acquisitions of nascent competitors than Section 7 of the Clayton Act. Compare
Hemphill & Wu, supra note 334, at 1896-1901 (discussing the advantages of Section 2); Melamed, supra note 334, at
6-7 (similar), with Scott Sher, Keith Klovers & John Ceccio, Nascent Competition, Section 2, and the Agencies’
Quixotic Quest to Avoid the Potential Competition Doctrine, ANTITRUST MAGAZINE ONLINE (Aug. 2021),
https://www.americanbar.org/content/dam/aba/publishing/antitrust-magazine-online/august-2021/atonline-sher.pdf
(arguing that Section 2 is less stringent than Section 7 as applied to mergers); Jonathan Jacobson & Christopher
Mufarrige, Acquisitions of “Nascent” Competitors, ANTITRUST SOURCE 5-6 (Aug. 2020),
https://www.americanbar.org/content/dam/aba/publishing/antitrust-magazine-online/2020/august-
2020/aug20_full_source.pdf (similar). Both approaches remain largely untested.
517 See, e.g., Yun, supra note 334, at 635 (“A considerable downside to bringing a nascent competition case under
[Section] 7 is that there are no court precedents for doing so. . . . Consequently, a court would need to develop new
conditions and requirements to find a violation, which is certainly a major impediment to applying the nascent
competition doctrine in [Section] 7 cases.”).
518 Platform Competition and Opportunity Act of 2021, H.R. 3826, 117th Cong. § 2(b)(2)(C)-(D) (2021).
519 Trust-Busting for the Twenty-First Century Act, S. 1074, 117th Cong. § 4 (2021).
520 Id.
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Other proposals are more limited. Several commentators, for example, have advocated a
requirement that Big Tech firms bear the burden of proving that their mergers would not harm
competition.521
Abstracting from specific policy options, the debate over special merger rules for Big Tech firms
has focused on two general concerns.
First, opponents of such rules have argued that Big Tech mergers are typically benign or
procompetitive.522 Acquisitions of complementary technologies, for example, may reduce the
transaction costs associated with licensing arrangements or allow for more efficient integration
with a platform’s offerings.523 Mergers may also stimulate competition among Big Tech firms by
giving them an attractive means of entering or expanding within each other’s core markets.524
Second, some have argued that limitations on Big Tech mergers may reduce startup investment by
eliminating a popular exit route for venture investors and other entrepreneurs.525
Proponents of special merger rules for tech platforms have responded that the procompetitive
benefits of tech mergers are often overstated.526 Merger limitations targeting a handful of
prospective acquirers may also leave startup investors with enough viable exit options to mitigate
concerns about dampened investment. Some commentators have also suggested that reducing
investment in innovations that end up in the hands of dominant incumbents is the intended
outcome of the relevant proposals.527
The Merger Review Process
Before moving on from mergers, one final topic warrants mention: the Hart-Scott-Rodino (HSR)
premerger review process. Under the HSR Act, parties to mergers that exceed certain thresholds
must report their transactions to the DOJ and FTC and abide by specified waiting periods before
closing.528 This process gives the agencies the opportunity to review proposed mergers for
antitrust concerns and seek relief before deals are consummated.
Some commentators have expressed concerns about the number of Big Tech mergers that fall
below the relevant thresholds and thus evade HSR review.529 In September 2021, the FTC

521 STIGLER REPORT, supra note 333, at 98, 111; ACCC Report, supra note 162, at 109; see also OECD STARTUP
ACQUISITION REPORT, supra note 334, at 38-41 (cataloguing various rebuttable-presumption proposals).
522 Samuel Bowman & Sam Dumitriu, Better Together: The Procompetitive Effects of Mergers in Tech, INT’L CTR. FOR
L. & ECON. (Oct. 1, 2021), https://laweconcenter.org/resources/better-together-the-procompetitive-effects-of-mergers-
in-tech/?doing_wp_cron=1676398306.5821518898010253906250; UK DIGITAL COMPETITION REPORT, supra note 333,
at 101 (concluding that regulators should adopt a “balance of harms” approach to platform mergers instead of a
presumption of illegality because “the majority of acquisitions by large digital companies are likely to be either benign
or beneficial for consumers”).
523 Bowman & Dumitriu, supra note 522; A. Douglas Melamed & Nicolas Petit, The Misguided Assault on the
Consumer Welfare Standard in the Age of Platform Markets, 54 REV. OF INDUS. ORG. 741, 754 (2019).
524 Bowman & Dumitriu, supra note 522.
525 Gary Dushnitsky & D. Daniel Sokol, Mergers, Antitrust, and the Interplay of Entrepreneurial Activity and the
Investments That Fund It, 24 VAND. J. OF ENT. & TECH. L. 255 (2022); Jacobson & Mufarrige, supra note 516, at 10;
UK DIGITAL COMPETITION REPORT, supra note 333, at 101.
526 John M. Newman, Antitrust in Digital Markets, 72 VAND. L. REV. 1497, 1541 (2019).
527 Hemphill & Wu, supra note 334, at 1893.
528 15 U.S.C. § 18a.
529 STIGLER REPORT, supra note 333, at 111.
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released a report indicating that the four Big Tech firms discussed in this report and Microsoft
together engaged in 819 non-reportable deals between 2010 and 2019.530
In response to worries about these transactions, some have supported a blanket HSR filing
requirement for Big Tech acquisitions.531 Opponents of such a rule have argued that it would be
burdensome and offer few benefits for regulators.532
Interoperability & Data Portability
Network effects and switching costs are frequent themes in discussions of Big Tech.533 Some
reform proposals seek to address these structural features of certain platform markets by imposing
interoperability and data-portability obligations on designated platform operators.534
In broad strokes, interoperability refers to the ability of distinct services to work together and
communicate with one another.535 Interoperability can develop organically—as with email and
many patent pools—or as a result of a legal mandate.536 Examples in the latter category include
the 1996 Telecommunications Act’s requirement that local exchange carriers interconnect with
other providers.537 The DOJ’s 2002 monopolization settlement with Microsoft also included an
interoperability provision prohibiting Microsoft from excluding other firms’ web browsers from
its Windows operating system.538
These types of measures seek to lower the entry barriers associated with networked industries by
shifting network effects from individual firms to the market as a whole, thus making them
available to nascent and potential competitors of a dominant incumbent.539
Data portability, by contrast, refers to a consumer’s right to move his or her data from one
platform to another.540 Telecommunications law again offers an example by granting phone users
the right to retain their phone numbers when they change carriers.541 Such requirements decrease
the switching costs that might otherwise discourage consumers from taking their business to a
more attractive provider.542

530 FTC NON-REPORTABLE ACQUISITIONS STUDY, supra note 332, at 10.
531 HJC REPORT, supra note 11, at 388.
532 ABA DIGITAL ECONOMY REPORT, supra note 358, at 16.
533 See, e.g., HJC REPORT, supra note 11, at 40-42; STIGLER REPORT, supra note 333, at 38-39, 109; UK DIGITAL
COMPETITION REPORT, supra note 333, at 35-36.
534 OECD, DATA PORTABILITY, INTEROPERABILITY AND DIGITAL PLATFORM COMPETITION (2021),
https://www.oecd.org/daf/competition/data-portability-interoperability-and-digital-platform-competition-2021.pdf
[hereinafter “OECD INTEROPERABILITY REPORT”]; HJC REPORT, supra note 11, at 384-86; STIGLER REPORT, supra note
333, at 109-10, 113; see also Kades & Scott Morton, supra note 345 (advocating interoperability remedies in antitrust
litigation involving tech platforms).
535 Ezrielev & Marquez, supra note 167, at 9; OECD INTEROPERABILITY REPORT, supra note 534, at 12.
536 Herbert Hovenkamp, Antitrust Interoperability Remedies, 123 COLUM. L. REV. F. 1, 10 (2023) [hereinafter
“Hovenkamp, Interoperability Remedies”].
537 47 U.S.C. § 251(c).
538 United States v. Microsoft Corp., 215 F. Supp. 2d 1 (D.D.C. 2002). For other examples of antitrust cases in which
interoperability has been used as a remedy, see Hovenkamp, Interoperability Remedies, supra note 536, at 13 n.74.
539 Kades & Scott Morton, supra note 345, at 41-42; Becky Chao & Ross Schulman, Promoting Platform
Interoperability, NEW AM. FDN. 21-22 (May 2020).
540 Michal S. Gal & Daniel L. Rubinfeld, Data Standardization, 94 NYU L. REV. 737, 739 (2019).
541 47 U.S.C. § 251(b)(2).
542 Juan Pablo Maicas, et al., Reducing the Level of Switching Costs in Mobile Communications: The Case of Mobile
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In the 117th Congress, H.R. 3849 would have imposed interoperability and data-portability duties
on designated digital platforms.543 The bill would have directed the FTC to develop standards
implementing those duties for individual covered platforms.544 In promulgating standards under
the legislation, the FTC would have been advised by technical committees that included
representatives of a platform’s competitors, competition and privacy-advocacy organizations, the
National Institute of Standards and Technology, and covered platforms.545
The obligations contemplated by H.R. 3849 were potentially broader than those in the AICOA,
which were discussed earlier in this report.546 The AICOA’s interoperability provision would
have prohibited a covered platform operator from restricting the ability of business users to
interoperate with features that are available to the operator’s own products or services.547
Accordingly, the prohibition would have been limited to a platform operator’s unequal treatment
of firms that utilize its platform.548
In contrast, H.R. 3849 would have granted the FTC rulemaking authority to impose potentially
broader, platform-specific interoperability obligations.549 For a social network like Facebook, an
interoperability rule might have included duties to allow users of other networks to “friend”
Facebook users and transmit posted content from Facebook to other networks.550 Supporters of
interoperability have argued that these types of obligations would catalyze competition by
allowing users of upstart social networks to benefit from Facebook’s scale.551
H.R. 3849’s data-portability provision was also potentially broader than the parallel requirement
in the AICOA. While the AICOA’s requirement would have applied only to a platform’s business
users,552 H.R. 3849’s data-portability obligation would have encompassed individuals who use a
covered platform.553
A rule implementing this duty might have required a social network like Facebook to keep a
user’s messages, photos, and other content in an accessible format that could be transferred to
other platforms.554 Although this type of requirement may have partially overlapped with the
ongoing transferability contemplated by H.R. 3849’s interoperability mandate, it could also have

Number Portability, 33 TELECOMMS. POL’Y 544 (2009).
543 ACCESS Act of 2021, H.R. 3849, 117th Cong. §§ 3-4 (2021).
544 Id. § 6(c).
545 Id. § 7.
546 See supra “Interoperability and Data Access.”
547 American Innovation and Choice Online Act, S. 2992, 117th Cong. § 3(a)(4) (2022) (Reported Version); American
Innovation and Choice Online Act, H.R. 3816, 117th Cong. § 2(b)(1) (2021) (Reported Version).
548 The reported House version of the AICOA also included a broader provision that prohibited covered platform
operators from restricting a business user’s ability to interoperate with “any product or service.” H.R. 3816 § 2(b)(9).
549 ACCESS Act of 2021, H.R. 3849, 117th Cong. §§ 4, 6 (2021); see also Schnitzer, et al., supra note 405, at 22
(contrasting the AICOA’s interoperability provision with the “general interoperability requirement” in H.R. 3849).
550 Kades & Scott Morton, supra note 345, at 16; Transcript of Markup of H.R. 3843, the Merger Filing Fee
Modernization Act, et al., at 48,832-48,835 (June 23, 2021) (on file with author) [hereinafter “H.R. 3849 Markup
Transcript”] (Rep. Mary Gay Scanlon) (“Much like texting allows iPhone owners to communicate with Android
owners, so, too, would [H.R. 3849] allow individuals switching to new social media platforms to be able to
communicate and interact with their friends and family on Facebook.”).
551 Kades & Scott Morton, supra note 345, at 9.
552 S. 2992 § 3(a)(4); H.R. 3816 § 2(b)(1).
553 H.R. 3849 § 3.
554 Hovenkamp, Interoperability Remedies, supra note 536, at 27.
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included categories of data not subject to continuous real-time interoperability for technical or
other reasons.555 Data-portability rules may likewise require Amazon to allow retailers on its
marketplace to port their customer reviews to rival e-commerce platforms and Apple to permit
iPhone users to transfer their message histories to an Android device.556
Objections to interoperability and data-portability mandates take several forms. Some have
highlighted the complexity of interoperability requirements, which may pose challenges of
implementation and enforcement.557 Others have focused on possible privacy and data-security
risks that might accompany both interoperability and data-portability rules.558
H.R. 3849 attempted to address complexity concerns by directing the FTC to establish technical
committees to assist with rule development.559 The bill sought to mitigate privacy and
data-security risks by imposing data-security requirements on firms that interoperate with or
receive ported data from a covered platform.560
Another category of criticism directed at interoperability requirements involves innovation
concerns. Some have worried that interoperability may result in homogenized markets as an
incumbent’s rivals coalesce around a single set of standards.561 Compelled interoperability also
potentially implicates the free-rider problems that motivate narrow duty-to-deal doctrine: by
requiring firms to share the fruits of their innovation with competitors, policymakers may dampen
incentives to invest in new products.562 Defenders of interoperability have acknowledged this
risk, but maintain that interoperating Big Tech platforms would still face incentives to innovate to
prevent rivals from gaining a competitive edge.563
Changes to General Antitrust
While the proposals discussed above would entail special competition rules for large tech
platforms, other options involve changes to general antitrust law. Because general antitrust reform
is a vast topic, this report does not attempt an exhaustive overview of the relevant proposals.
Instead, it briefly reviews selected bills involving exclusionary conduct and merger law.

555 See id. (arguing that “dynamic” interoperability for social networks might be technically difficult and that the
“static” interoperability offered by data portability may thus be a more promising option).
556 H.R. 3849 Markup Transcript, supra note 550, at 4,564-4,568 (Rep. David Cicilline).
557 See, e.g., Hovenkamp, Interoperability Remedies, supra note 536, at 35; Randy Picker, Forcing Interoperability on
Tech Platforms Would Be Difficult to Do, PROMARKET (Mar. 11, 2021), https://www.promarket.org/2021/03/11/
interoperability-tech-platforms-1996-telecommunications-act/.
558 See, e.g., Laura Alexander & Randy Stutz, Interoperability in Antitrust Law & Competition Policy, COMPETITION
POLICY INT’L ANTITRUST CHRON. 31, 36 (June 2021); OECD INTEROPERABILITY REPORT, supra note 534, at 24; Peter
Swire & Yianni Lagos, Why the Right to Data Portability Likely Reduces Consumer Welfare: Antitrust and Privacy
Critique, 72 MD. L. REV. 335, 365-75 (2013).
559 ACCESS Act of 2021, H.R. 3849, 117th Cong. § 6 (2021).
560 Id. §§ 3(b), 4(b).
561 Hovenkamp, Interoperability Remedies, supra note 536, at 35; Ezrielev & Marquez, supra note 167, at 10-11.
562 See, e.g., FUMAGALLI, et al., supra note 73, at 547; ABA Letter, supra note 391, at 14; Ezrielev & Marquez, supra
note 167, at 10-11; Howard A. Shelanski, Unilateral Refusals to Deal in Intellectual and Other Property, 76
ANTITRUST L.J. 369, 371 (2009).
563 Kades & Scott Morton, supra note 345, at 26.
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Exclusionary Conduct
S. 225, the Competition and Antitrust Law Enforcement Reform Act (117th
Cong.)
In the 117th Congress, S. 225 would have made several changes to the legal framework
governing exclusionary-conduct claims.564 The bill would have amended the Clayton Act to
prohibit “exclusionary conduct that presents an appreciable risk of harming competition.”565
“Exclusionary conduct” would have been defined to mean conduct that (1) “materially
disadvantages” an actual or potential competitor, or (2) “tends to foreclose or limit” the ability of
an actual or potential competitor to compete.566
S. 225 would have adopted a presumption that exclusionary conduct presents “an appreciable risk
of harming competition” if it is undertaken by a firm with a market share of greater than 50
percent or that otherwise has “significant market power” in the relevant market.567 That
presumption could be rebutted, however, if a defendant established by a preponderance of the
evidence that:
1. “distinct procompetitive benefits of the exclusionary conduct in the relevant
market eliminate the risk of harming competition presented by the exclusionary
conduct”;
2. another firm has “entered or expanded their presence in the market with the effect
of eliminating the risk of harming competition posed by the exclusionary
conduct”; or
3. “the exclusionary conduct does not present an appreciable risk of harming
competition.”568
The bill would have provided that several of the conduct-specific tests that courts have adopted in
Sherman Act cases would not apply to exclusionary-conduct claims under the amended Clayton
Act. Among other things, exclusionary-conduct plaintiffs would not have to show:
 that a defendant terminated a prior course of dealing,569 which some courts have
held is a prerequisite for refusal-to-deal liability under the Sherman Act;570
 that the defendant priced its products below its costs or is likely to recoup losses
from below-cost pricing,571 which are both requirements for predatory-pricing
claims under the Sherman Act;572 or

564 Competition and Antitrust Law Enforcement Reform Act of 2021, S. 225, 117th Cong. §§ 9, 13 (2021).
565 Id. § 9.
566 Id.
567 Id.
568 Id.
569 Id.
570 E.g., Novell, Inc. v. Microsoft Corp., 731 F.3d 1064, 1075 (10th Cir. 2013) (Gorsuch, J.).
571 Competition and Antitrust Law Enforcement Reform Act of 2021, S. 225, 117th Cong. § 9 (2021).
572 Brooke Grp. Ltd. v. Brown & Williamson Tobacco Corp., 509 U.S. 209, 222-24 (1993).
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 that the conduct of a multi-sided platform presents an appreciable risk of harming
competition on more than one side of the platform,573 contrary to the rule the
Supreme Court adopted for two-sided transaction platforms in Amex.574
S. 225 also would have provided that market definition is not necessary to prove an antitrust
violation, except in cases where the applicable statute includes the phrase “relevant market,”
“market concentration,” or “market share.”575
S. 1074, the Trust-Busting for the Twenty-First Century Act (117th Cong.)
S. 1074—another bill in the 117th Congress—also would have made changes to the standards
governing exclusionary-conduct claims.576 The legislation would have provided that, in litigation
under Section 1 or Section 2 of the Sherman Act, a defendant that relies upon procompetitive
effects to justify its conduct must establish by clear and convincing evidence that:
1. the relevant procompetitive effects “clearly outweigh” any anticompetitive
effects; and
2. the defendant “could not obtain substantially similar procompetitive effects
through commercially reasonable alternatives that would involve materially
lower competitive risks.”577
Like S. 225, the bill would have provided that market definition is not required to prove a
violation of Section 1 or Section 2.578
Mergers
S. 225, the Competition and Antitrust Law Enforcement Reform Act (117th
Cong.)
In addition to the exclusionary-conduct provisions discussed above, S. 225 would have modified
several aspects of merger law. The bill would have amended Section 7 of the Clayton Act to
prohibit mergers that “create an appreciable risk of materially lessening” competition579—a
change from the current language that prohibits mergers that may “substantially” lessen
competition.580 The term “materially” was defined to mean “more than a de minimis amount.”581
S. 225 also would have shifted the relevant burden of proof to the merging parties in certain
circumstances.582 For example, merging parties would have had the burden of proving that their
transactions would not “create an appreciable risk of materially lessening” competition in cases
where:

573 S. 225 § 9.
574 Ohio v. Am. Express Co., 138 S. Ct. 2274, 2286-87 (2018).
575 S. 225 § 13(a).
576 Trust-Busting for the Twenty-First Century Act, S. 1074, 117th Cong. § 2 (2021).
577 Id.
578 Id.
579 S. 225 § 4(b)(1).
580 15 U.S.C. § 18.
581 S. 225 § 4(b)(3).
582 Id.
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 a merger would lead to a “significant increase in market concentration”;
 a firm with a market share greater than 50 percent or that possesses “significant
market power” acquires a competitor or a company that has a “reasonable
probability” of becoming a competitor;
 a transaction is valued at more than $5 billion; or
 the acquiring firm has assets, net revenue, or a market capitalization exceeding
$100 billion and the transaction is valued at $50 million or more.583
S. 1074, the Trust-Busting for the Twenty-First Century Act (117th Cong.)
S. 1074 also included merger restrictions.584 The bill would have prohibited firms with market
capitalizations exceeding $100 billion from engaging in mergers whose effect “may be to lessen
competition in any way.”585 It also would have explicitly provided that market definition is not
necessary to block a merger and that mergers shall not be presumed to be legal on the grounds
that the parties are not direct competitors.586
S. 3847, the Prohibiting Anticompetitive Mergers Act (117th Cong.)
In the 117th Congress, S. 3847 would have taken a similarly skeptical approach to large mergers.
The legislation would have prohibited mergers valued at more than $5 billion, mergers that result
in a market share of over 33 percent for sellers or 25 percent for employers, and mergers that
would result in specified levels of market concentration.587
S. 3847 also would have made changes to the merger-review process.588 Among other things, the
bill would have extended the initial HSR waiting period from 30 days to 120 days and allowed
the antitrust agencies to block mergers without obtaining a court order.589
In addition, the bill would have directed the DOJ and FTC to review mergers consummated after
January 1, 2000, if they would have qualified as “prohibited mergers” under the categories
mentioned above.590 It would have further required the agencies to pursue remedies to restore
competition or address the anticompetitive effects of these mergers in specified circumstances.591

583 Id.
584 S. 1074 contained both size-based merger restrictions and merger restrictions that would have applied to companies
designated as “dominant digital firms.” Trust-Busting for the Twenty-First Century Act, S. 1074, 117th Cong. §§ 3, 4
(2021). The latter are discussed in supra “Substantive Merger Law.”
585 S. 1074 § 3.
586 Id.
587 Prohibiting Anticompetitive Mergers Act of 2022, S. 3847, 117th Cong. § 3 (2022). The market-concentration
prohibition would have barred mergers that would (1) result in a Herfindahl-Hirschman Index (HHI) of greater than
1,800, and (2) increase the relevant HHI by more than 100 points. Id. A market with an HHI of 1,800 qualifies as
“moderately concentrated” under the current Horizontal Merger Guidelines, but would have been deemed to be “highly
concentrated” under the 1992 version of the Guidelines. HORIZONTAL MERGER GUIDELINES, supra note 100, at § 5.3;
DEP’T OF JUSTICE AND FED. TRADE COMM’N, 1992 MERGER GUIDELINES § 1.5 (1992).
588 S. 3847 § 4(b).
589 Id.
590 Id. § 6.
591 Id.
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Author Information

Jay B. Sykes

Legislative Attorney

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Congressional Research Service
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