Patent Law: A Handbook for Congress

Patent Law: A Handbook for Congress
September 16, 2020
A patent gives its owner the exclusive right to make, use, import, sell, or offer for sale the
invention covered by the patent. The patent system has long been viewed as important to
Kevin T. Richards
encouraging American innovation by providing an incentive for inventors to create. Without a
Legislative Attorney
patent system, the reasoning goes, there would be little incentive for invention because anyone

could freely copy the inventor’s innovation.

Congressional action in recent years has underscored the importance of the patent system,
including a major revision to the patent laws in 2011 in the form of the Leahy-Smith America Invents Act. Congress has also
demonstrated an interest in patents and pharmaceutical pricing; the types of inventions that may be patented (also referred to
as “patentable subject matter”); and the potential impact of patents on a vaccine for COVID-19.
As patent law continues to be an area of congressional interest, this report provides background and descriptions of several
key patent law doctrines. The report first describes the various parts of a patent, including the specification (which describes
the invention) and the claims (which set out the legal boundaries of the patent owner’s exclusive rights). Next, the report
provides detail on the basic doctrines governing patentability, enforcement, and patent validity.
For patentability, the report details the various requirements that must be met before a patent is allowed to issue. These
requirements include the following:
Patentable Subject Matter. The claimed invention must be directed to one of the statutorily defined
categories of patent-eligible subject matter.
Definiteness. The patent claims defining the invention’s legal boundaries must be sufficiently clear.
Written Description. The specification must adequately describe the invention.
Enablement. The specification must enable a person in the field of the relevant technology to make and
use the invention.
Novelty. The invention cannot be the same as something known in the “prior art” (i.e., public knowledge in
the field of relevant technology at the time of invention).
Nonobviousness. The invention cannot be an obvious extension of the prior art.
The report then explains how the rights granted by a patent are enforced, including issues relating to patent infringement
(such as direct infringement, infringement under the doctrine of equivalents, induced infringement, and contributory
infringement). Also addressed are issues relating to litigation in federal district court and before the International Trade
Commission (ITC), including the specialized dispute procedures governed by the Drug Price Competition and Patent Term
Restoration Act of 1984 (Hatch-Waxman Act) and the Biologics Price Competition and Innovation Act of 2009 (BPCIA).
Finally, the report explains how a patent owner may lose their patent. This includes discussions of ex parte reexamination,
post-grant review, inter partes review, and covered business method review.
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What Is a Patent? ............................................................................................................................. 2
Parts of a Patent ......................................................................................................................... 2
Rights Conferred by a Patent .................................................................................................... 6
Patent Appeals ........................................................................................................................... 8
Patent Requirements ........................................................................................................................ 8
Inventorship Requirements ..................................................................................................... 10
The Person of Ordinary Skill ................................................................................................... 11
Claim Construction .................................................................................................................. 11
Patent Application Requirements ............................................................................................ 12
Claim Clarity ..................................................................................................................... 12
Specification Contents ...................................................................................................... 13
Patentability............................................................................................................................. 14
Patentable Subject Matter ................................................................................................. 14
Novelty .............................................................................................................................. 15
Nonobviousness ................................................................................................................ 16
Maintenance Fees .................................................................................................................... 17
Patent Infringement and Enforcement ........................................................................................... 17
Proving Patent Infringement ................................................................................................... 17
Direct Infringement ........................................................................................................... 17
Indirect Infringement ........................................................................................................ 18
Enforcing a Patent ................................................................................................................... 19
District Court Enforcement ............................................................................................... 19
International Trade Commission Enforcement ................................................................. 20
Specialized Dispute Procedures for Certain Pharmaceuticals .......................................... 22
Patent Invalidation and Cancellation ............................................................................................. 23
District Court Litigation .......................................................................................................... 23
PTO Administrative Proceedings ............................................................................................ 24
Ex Parte Reexamination .................................................................................................... 24
Post-Grant Review ............................................................................................................ 24
Inter Partes Review ........................................................................................................... 25
Covered Business Method Review ................................................................................... 26
Comparison of PTO Proceedings ...................................................................................... 26

Considerations for Congress.......................................................................................................... 28

Table 1. PTO Post-Issuance Proceedings ...................................................................................... 27

Author Information ........................................................................................................................ 30

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Patent Law: A Handbook for Congress

he patent system has long been viewed as important to encouraging American innovation.
Abraham Lincoln, in a speech before he became President, argued that the patent system
T “added the fuel of interest to the fire of genius, in the discovery and production of new and
useful things.”1 In Mark Twain’s A Connecticut Yankee in King Arthur’s Court, the titular
Connecticut Yankee related that “the very first official thing I did, in my administration—and it
was on the very first day of it, too—was to start a patent office; for I knew that a country without
a patent office and good patent laws was just a crab, and couldn’t travel any way but sideways or
backways.”2 Upon commencing patent infringement litigation against Kodak, Polaroid founder
Edwin Land, inventor of the instant camera, explained that “[t]he only thing that keeps us alive is
our brilliance. The only way to protect our brilliance is our patents.”3
Patents and intellectual property (IP) remain important today. In 2019, the U.S. Patent and
Trademark Office (PTO) issued 354,507 new patents—the most in its history.4 In 2016, a joint
report from the Economics and Statistics Administration and the PTO estimated that patent-
intensive industries added 3.9 million jobs to the U.S. economy.5 The same report estimated that
patent-intensive industries added $881 billion in value to the U.S. gross domestic product (GDP),
comprising 5.1% of the U.S. GDP.6
Patents also are an important aspect of technology and health care in the United States. It has
been estimated that a single smartphone may be protected by as many as 250,000 patents.7 New
pharmaceuticals are often protected by patents;8 indeed, intellectual property rights, including
patent rights, are generally considered to play an essential role in encouraging the research and
development necessary to create new pharmaceutical products.9 For example, one recent study of
the top twelve drugs by gross U.S. revenue found that pharmaceutical manufacturers obtained an
average of seventy-one patents on each of these drugs.10 Whether and to what extent any

1 Abraham Lincoln, Second Lecture on Discoveries and Inventions (Feb. 11, 1859) in 3 COLLECTED WORKS OF
ABRAHAM LINCOLN 356, 363 (Roy P. Basler, ed. 2001).
3 Victor K. McElheny, Polaroid Is Suing Kodak, Charges Patent Violation, N.Y. TIMES (Apr. 28, 1976), at
suing.html. Polaroid and Kodak eventually settled their dispute in 1991, with Kodak agreeing to pay Polaroid $925
million. Reuters, Kodak Settles With Polaroid, N.Y. TIMES (July 16, 1991), at
business/kodak-settles-with-polaroid.html. Land had died earlier that year. Eric Pace, Edwin H. Land Is Dead at 81;
Inventor of Polaroid Camera
, N.Y TIMES (March 2, 1991), at
4 Dennis Crouch, How Many Patents Issued in 2019?, PATENTLYO (Dec. 31, 2019), at
5 Robert Rubinovitz et al., Intellectual Property & the U.S. Economy: 2016 Update, at ii, ECONOMICS & STATISTICS
6 Id. at 22.
7 Steve Lohr, Apple-Samsung Patent Battle Shifts to Trial, N.Y. TIMES, (July 29, 2012), at
2012/07/30/technology/apple-samsung-trial-highlights-patent-wars.html. Notably, not all of the patents covering
aspects of a smartphone are owned by the same entity. Id.
8 See generally CRS Report R46221, Drug Pricing and Pharmaceutical Patenting Practices, coordinated by Kevin T.
Richards, at 9-10, 16-20, 24-28.
9 Henry G. Grabowski et al., The Roles of Patents and Research and Development Incentives in Biopharmaceutical
, 34 HEALTH AFF. 302, 302 (2015) (“Patents and other forms of intellectual property protection are generally
thought to play essential roles in encouraging innovation in biopharmaceuticals.”).
10 See Overpatented, Overpriced: How Excessive Pharmaceutical Patenting Is Extending Monopolies and Driving Up
Drug Prices
, I-MAK 6-8 (Aug. 2018), at
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countermeasures against COVID-19 should be patented has also been a subject of congressional
As patents and IP remain a subject of congressional interest, this report provides an overview of
U.S. patent law. It begins by describing the various parts of a patent to provide context and
background for the legal discussion. It then describes the legal requirements that must be met in
order to obtain a patent and how the rights granted by a patent may be enforced. Finally, the
report closes with a description of how patent rights may be lost, either through litigation or
through administrative proceedings before the PTO’s Patent Trial and Appeal Board.
What Is a Patent?
The Constitution empowers Congress to “promote the Progress of Science and useful Arts, by
securing for limited Times to ... Inventors the exclusive Right to their respective ...
Discoveries.”12 Since 1790, Congress has enacted patent laws pursuant to this power, granting
inventors certain exclusive rights in their inventions for a period of time.13 Broadly speaking,
those exclusive rights are granted in return for the inventor’s public disclosure of the invention.14
Thus, patents represent a “quid pro quo”: in return for the inventor’s public disclosure, the
inventor receives those time-limited exclusive rights.15 Many of the specific doctrines underlying
patent law can be explained by that rationale.
Parts of a Patent
Before describing the exclusive rights granted by a patent and related issues (such as how to
obtain, enforce, and lose a patent), it is helpful to understand the basic parts of a patent.16 For
example, before describing the legal requirements for patent claims,17 it is important to
understand what patent claims are. Recently issued U.S. Patent No. 10,000,000 (the ’000 patent)
provides a good illustration of a patent’s format.18

11 See, e.g., Press Release, Office of Representative Jan Schakowsky, Congressional Progressive Leaders Announce
Principles On COVID-19 Drug Pricing for Next Coronavirus Response Package (Apr. 15, 2020), at
12 U.S. CONST. art. I, § 8, cl. 8.
13 See, e.g., 35 U.S.C. § 271 (setting forth how patents may be infringed).
14 J.E.M. Ag Supply, Inc. v. Pioneer Hi-Bred Int’l, Inc., 534 U.S. 124, 142 (2001) (“The disclosure required by the
Patent Act is ‘the quid pro quo of the right to exclude.’” (quoting Kewanee Oil Co. v. Bicron Corp., 416 U.S. 470, 484
(1974))); see also Universal Oil Prod. Co. v. Globe Oil & Ref. Co., 322 U.S. 471, 484 (1944) (“As a reward for
inventions and to encourage their disclosure, the United States offers a ... monopoly to an inventor who refrains from
keeping his invention a trade secret. But the quid pro quo is disclosure of a process or device in sufficient detail to
enable one skilled in the art to practice the invention once the period of the monopoly has expired; and the same
precision of disclosure is likewise essential to warn the industry concerned of the precise scope of the monopoly
15 J.E.M. Ag Supply, 534 U.S. at 142.
16 The following description and legal requirements relate only to utility patents. Design patents, which protect a “new,
original and ornamental design for an article of manufacture,” see 35 U.S.C. §§ 171-73, and plant patents, which
protect “any distinct and new variety of plant,” see id. §§ 161-64, are beyond the scope of this report.
17 See discussion infra in “Patent Application Requirements.”
18 U.S. Patent 10,000,000 was issued, with much fanfare, on June 19, 2018. U.S. Patent No. 10,000,000; United States
Issues Patent Number 10,000,000
, U.S. PAT. & TRADEMARK OFF. (June 19, 2018), at
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Patent Law: A Handbook for Congress

As shown below, a patent’s cover page provides basic information about the patent, including the
name(s) of the inventor(s), the title of the patent, the date that the patent issued, an abstract briefly
summarizing the invention,19 and a representative drawing:

The cover page is followed by drawings illustrating background technology; various aspects of
the invention; or different implementations of the invention. For example, Figure 4 of the ’000
patent illustrates use of the invention in an exemplary environment:20

us/news-updates/united-states-issues-patent-number-10000000; U.S. Patent 10 Million, U.S. PAT. & TRADEMARK OFF.,
19 Because the purpose of this discussion and description is to familiarize the reader with the various parts of a patent,
rather than specifically familiarize the reader with the innovations underlying the ’000 patent, description of the
relevant technological background and specific advance claimed by the ’000 patent are omitted from this report.
20 ’000 patent, col. 6 ll. 7-59.
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Patent Law: A Handbook for Congress

Following the drawings is the specification, a textual description of the invention set out in two-
column pages. As shown in the excerpt below, the description relating to Figure 4 appears in
column six beginning at line seven (annotated with a red box):
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Patent Law: A Handbook for Congress

The textual description must meet specific legal requirements in order for the patent to be valid.21
Following this textual description (and concluding the patent) are the patent claims, a series of
numbered paragraphs setting forth what the inventor regards as his invention.22 These claims
form the metes and bounds of the patent right; in other words, the claims define the scope of the

21 Those requirements are explained in detail infra. See discussion infra in “Patent Application Requirements.”
22 1 ROBERT A. MATTHEWS, JR., ANNOTATED PATENT DIGEST § 1:24 (2020) (“The end of each specification contains a
series of numbered paragraphs [where] the patent applicant defines in concise terms the specific invention that the
patent applicant particularly claims as his invention. These paragraphs are referred to as patent claims.”).
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Patent Law: A Handbook for Congress

invention, and thus the scope of the legal rights granted by the patent.23 Some of the ’000 patent’s
claims appear below:

The individual clauses within each patent claim are limitations that serve to define the
invention.24 Those limitations, taken together, set forth what has been invented. Independent
generally do not reference other claims; for example, claim 1 of the ’000 patent is an
independent claim. Dependent claims, on the other hand, reference and incorporate the limitations
of previous claims;25 for example, claims 2 and 3 of the ’000 patent are dependent claims. Patent
claims have specific legal requirements, which are explained in more detail later in the report.26
Rights Conferred by a Patent
A patent confers certain legal rights on its owner. Specifically, the patent owner may exclude
others from making, using, importing, offering for sale, or selling the invention (collectively,

23 Thorner v. Sony Ent. Am. LLC, 669 F.3d 1362, 1367 (Fed. Cir. 2012) (“It is the claims that define the metes and
bounds of the patentee’s invention.” (citation omitted)).
24 Hyatt v. Dudas, No. CIV A 04-1138 HHK, 2006 WL 2521242, at *1 (D.D.C. Aug. 30, 2006), aff’d, 551 F.3d 1307
(Fed. Cir. 2008) (“[A] single claim can be composed of multiple elements and/or limitations.... Limitations ... usually
describe the claim’s restrictions, or the interaction between or features of the claim’s elements. An application may
contain several claims, and each claim usually contains several limitations.”); see also Bell Commc’ns Rsch., Inc. v.
Vitalink Commc’ns Corp., 55 F.3d 615, 619 (Fed.Cir.1995) (“[T]he language of the claim defines the scope of the
protected invention.”).
25 35 U.S.C. § 112(d) (“[A] claim in dependent form shall contain a reference to a claim previously set forth and then
specify a further limitation of the subject matter claimed. A claim in dependent form shall be construed to incorporate
by reference all the limitations of the claim to which it refers.”).
26 See discussion infra in “Patent Application Requirements.”
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Patent Law: A Handbook for Congress

“practicing the invention”).27 Notably, the patent includes only negative rights to exclude others
from practicing the invention;28 the patent grant does not include the positive right for the patent
owner to do so.29 In other words, a patent allows the owner to prevent others from making, using,
importing, offering for sale, or selling the invention, but does not give the patent owner the power
to perform those acts affirmatively.30 In some circumstances, a patented invention when practiced
in a particular manner may itself infringe another patent.31 The infringed patent is referred to as a
blocking patent because it blocks practice of the patented invention.32 Blocking patents may arise,
for example, when a patent’s claims are directed to an improvement on another patented
invention.33 In that case, the original patent may “block” practice of the patent on the
The exclusive rights granted by the patent begin on the date that the patent issues, and generally
expire twenty years from the date that the patent application was filed with the PTO.35 The patent
term may be extended under certain circumstances; for example, to compensate for time spent in
regulatory review (such as before the Food and Drug Administration (FDA) in the context of
pharmaceutical patents)36 or for delays due to certain PTO procedural failures.37
Patents “have the attributes of personal property.”38 Accordingly, although title in an invention
initially vests with the inventor, that interest may be transferred or assigned to others.39 It is
common for employment contracts to include provisions under which an employee assigns his
interest in any patents developed in the course of employment to the employer.40 Similarly,
patents may be sold from one party to another.41 A patent owner may also form a contract with

27 35 U.S.C. § 271(a). See also Bloomer v. McQuewan, 55 U.S. 539, 549 (1852) (“The franchise which the patent
grants, consists altogether in the right to exclude every one from making, using, or vending the thing patented, without
the permission of the patentee. This is all that he obtains by the patent.”).
28 See Bloomer, 55 U.S. at 549.
29 Animal Legal Def. Fund v. Quigg, 932 F.2d 920, 935 (Fed. Cir. 1991) (“It should hardly need saying that the
issuance of a patent gives no right to make, use or sell a patented invention ....”).
30 Id.
31 See Robert Merges, Intellectual Property Rights and Bargaining Breakdown: The Case of Blocking Patents, 62
TENN. L. REV. 75, 80-82 (1994).
32 See id.
33 Id.
34 Id.
35 35 U.S.C. § 154(a)(2). For patents whose application was filed before June 8, 1995, the patent term is seventeen
years from the date of issuance; for patents whose application was filed after that date, the patent term is twenty years
from the earliest date to which the application claims priority. Novartis Pharm. Corp. v. Breckenridge Pharm. Inc., 909
F.3d 1355, 1358 (Fed. Cir. 2018). Before the change in patent term, patent applications could remain pending for many
years (in some cases, decades) before issuing and then disrupting developed industries because the term ran from the
date of issuance. See Mark A. Lemley & Kimberley A. Moore, Ending Abuse of Patent Continuations, 84 B.U. L. REV.
63, 79-80 (2004).
36 See generally 35 U.S.C. § 156.
37 Id. § 154(b).
38 Id. § 261.
39 See id.; Beech Aircraft Corp. v. EDO Corp., 990 F.2d 1237, 1248 (Fed. Cir. 1993) (“[T]he patent right initially vests
in the inventor who may then, barring any restrictions to the contrary, transfer that right to another, and so forth.”).
40 See, e.g., Daniel F. Spulber, Intellectual Contract and Intellectual Law, 23 J. TECH. L. & POL’Y 1, 55 (2018); Robert
P. Merges, The Law and Economics of Employee Inventions, 13 HARV. J.L. & TECH. 1, 2 (1999).
41 See, e.g., Steve Lohr, Microsoft’s AOL Deal Intensifies Patent Wars, N.Y. TIMES (April 9, 2012), at
(describing Microsoft’s purchase of more than 800 patents held by America Online for more than $1 billion).
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another party permitting the other party to make, use, import, or sell a patented invention in return
for compensation (e.g., a lump sum payment or a continuing royalty).42 Such a contract is referred
to as a license.43
Patent Appeals
Unlike most cases in federal court, appeals involving patent law are heard by a single appellate
court—the U.S. Court of Appeals for the Federal Circuit (Federal Circuit).44 (Appeals from
decisions of U.S. district courts in most nonpatent cases are heard by the various U.S. Courts of
Appeals for different geographical regions or circuits.) Sitting in Washington, DC, Congress
created the Federal Circuit in 1982 in an effort to unify and standardize patent law.45 Although the
Supreme Court left the Federal Circuit’s interpretations of patent law essentially undisturbed
during the first two decades of the Federal Circuit’s existence, in recent years the Supreme Court
has taken more interest in patent law cases.46 In many of those cases, the Supreme Court has
reversed the Federal Circuit’s interpretation of patent law.47 Nevertheless, Federal Circuit
decisions play a large role in the acquisition and enforcement of patent rights in the United States.
Patent Requirements
The process for receiving a patent begins with the filing of an application with the PTO.48 A PTO
patent examiner then reviews the application for compliance with the substantive requirements

42 Thomas R. Varner, An Economic Perspective on Patent Licensing Structure and Provisions, 47 LES NOUVELLES 28,
32 (2012) (finding, based on a study of nearly 1,500 licensing agreements filed with the Securities and Exchange
Commission between 1994 and 2010, that 83% of licenses used a royalty with a rate based on percentage of sales,
number of units sold, percentage of profits, or percentage of costs).
43 MATTHEWS, supra note 22, at 5 § 35:28 (“In essence, a patent license is a permission, backed by a contractual
promise not to sue, for a party to perform acts that without the license would be deemed acts of infringement.”). See
35 U.S.C. § 261 (“Applications for patent, patents, or any interest therein, shall be assignable in law by an
instrument in writing. The applicant, patentee, or his assigns or legal representatives may in like manner grant and
convey an exclusive right under his application for patent, or patents, to the whole or any specified part of the United
44 Daniel Kazhdan, Beyond Patents: The Supreme Court’s Evolving Relationship with the Federal Circuit, 94 J. PAT. &
TRADEMARK OFF. SOC’Y 275, 294 (2012) (“[U]nlike regional courts of appeals, because the Federal Circuit has
exclusive jurisdiction over the questions of law that it decides, it can create uniformity.”).
11 (1991). See also Timothy R. Holbrook, The Federal Circuit’s Acquiescence(?), 66 AM. U. L. REV. 1061, 1065
(2017) (“When the Federal Circuit was created, it had a monumental task on its hands: creating uniformity from the
morass of patent case law developed by the regional circuits.”). The Federal Circuit has exclusive jurisdiction in a
number of nonpatent areas as well, including appeals from the PTO, the U.S. Court of Appeals for Veterans Claims, the
U.S. Court of Federal Claims, the U.S. International Trade Commission, and the U.S. Court of International Trade. 28
U.S.C. § 1295.
46 Paul R. Gugliuzza, The Supreme Court Bar at the Bar of Patents, 95 NOTRE DAME L. REV. 1233, 1234-35 (2020);
Peter Lee, The Supreme Assimilation of Patent Law, 114 MICH. L. REV. 1413, 1421-22 (2016); Timothy R. Holbrook,
The Return of the Supreme Court to Patent Law, 1 AKRON INTELL. PROP. J. 1, 2 (2007); John F. Duffy, The Festo
Decision and the Return of the Supreme Court to the Bar of Patents
, 2002 SUP. CT. REV. 273, 274 (2002).
47 Samuel F. Ernst, A Patent Reformist Supreme Court and Its Unearthed Precedent, 29 FORDHAM INTELL. PROP.
MEDIA & ENT. L.J. 1, 5 (2018) (“Since the year 2000, the Supreme Court has reversed or vacated the Federal Circuit in
patent law cases in 74% of the opinions it has issued reviewing that court ....”); H.R. Rep. No. 112-98, at 39 (2011)
(“[T]he need to modernize our patent laws has found expression in the courts, as well. The Supreme Court has reversed
the Federal Circuit in six of the patent-related cases that it has heard since the beginning of the 109th Congress.”).
48 See generally 35 U.S.C. § 111.
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for receiving a patent.49 If the examiner determines that the application does not meet one of the
requirements, she will reject the application.50 The applicant may generally then amend the
application in an effort to overcome the examiner’s rejection.51 Once the examiner determines
that an application meets all of the patentability requirements, she “allows” the application to
issue as a patent.52 Patent prosecution is the process of applying for a patent, addressing examiner
concerns, and receiving the patent.53 As PTO examiners are generally not lawyers,54 but rather are
subject specialists in the relevant science and/or technology area, the PTO issues the Manual of
Patent Examining Procedure
(MPEP) as guidance for examiners and practitioners.55
The following sections outline the requirements that a patent applicant must satisfy to receive a
patent. The discussion begins with two preliminary explanations. First, a discussion of who may
receive a patent—an area with some emerging issues in view of the rise of artificial intelligence
(AI) in recent years. Second, a discussion of one of the core concepts in analyzing patentability:
the “person of ordinary skill.” The sections that follow then address the substantive requirements
for patentability. Those substantive requirements broadly fall into two groups. First are
requirements of the patent application; that is, requirements regarding the specification that
describes the invention, and the level of clarity required in the patent claims. Second are the
requirements of the invention; namely, that the claimed invention must be patentable subject
matter and not be too similar to what has come before. Examiners may reject patent claims that
fail to meet one or more of these requirements while the application is still pending.56 If a patent
claim issues as part of a patent and is later determined to fail one or more of these requirements,
then that claim is generally “invalid” and subject to challenge if it is enforced.57

49 See JAMES E. HAWES & FREDERIC M. DOUGLAS, PATENT APPLICATION PRACTICE § 2:4 (2020) (providing an overview
of the patent application process); General Information Concerning Patents, U.S. PAT. & TRADEMARK OFF. (Oct. 2015),
50 HAWES & DOUGLAS, supra note 49, § 14:2.
51 Id. § 15.7-15.19.
52 Id. § 21.1.
53 Nick Cornor, Are Changes to the U.S. Patent System Objectively Killing Innovation?, 24 CURRENTS: J. INT’L ECON.
L. 87, 90 (2020) (“Patent prosecution refers to the process of applying for a patent.”). Although the foregoing
discussion provides a high-level overview of the process, patent prosecution is governed by specific laws and
regulations, the detailed discussion of which could fill its own report. See generally HAWES & DOUGLAS, supra note 49.
54 Lital Helman, Decentralized Patent System, 20 NEV. L.J. 67, 89 (2019) (“PTO examiners are not lawyers.”); Greg
Reilly, Decoupling Patent Law, 97 B.U. L. REV. 551, 592 (2017) (“Inherently legal tasks—like parsing the wording of
documents, analogizing and distinguishing precedent, and applying canons of document interpretation—are better
suited for legally trained judges than legally limited patent examiners.”).
55 See Manual of Patent Examining Procedure, U.S. PAT. & TRADEMARK OFF. (9th ed. June 2020), at
56 HAWES & DOUGLAS, supra note 49, § 14:2.
57 Steven Adamson, Pharmaceutical Patent Wars, Reverse-Payment Settlements, and Their Anticompetitive Effects for
, 30 LOY. CONSUMER L. REV. 241, 267 (2018) (“[A]n invalid patent does not meet the statutory
requirements.”); Connell v. Sears, Roebuck & Co., 722 F.2d 1542, 1552 (Fed. Cir. 1983) (“No claim of a patent
declared invalid can be enforced ....”).
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Inventorship Requirements
Under current law, only natural persons may be listed as an inventor on a patent.58 However, it is
common for inventors to assign their patent rights to their employers.59 Further, anyone to whom
the inventor has assigned or is under an obligation to assign patent rights may apply for a patent
in the inventor’s name.60
An emerging issue is whether an AI device may qualify as a patent’s inventor. In a recent
decision, the PTO rejected a patent application where the listed inventor was an AI device.61 In
that case, the application named an AI device called “DABUS” as the inventor.62 The application
further stated that “the invention was autonomously generated by artificial intelligence.”63 The
PTO ruled that an AI could not be an inventor because, in its view, the relevant statutory
provisions permitted only natural persons to be inventors.64 For example, the PTO reasoned, the
patent statutes repeatedly refer to the inventor as an “individual,”65 and other provisions of the
Patent Act state that “[w]hoever” creates a new invention may receive a patent, both of which
suggested that the inventor must be a natural person.66 Finally, the PTO reasoned that the Federal
Circuit had indicated in the past under different circumstances that an inventor must be a natural
person (although the Federal Circuit has not directly confronted the question whether an AI
device may be an inventor).67 The European Patent Office has similarly rejected patent
applications naming DABUS as an inventor.68
The question of who invented a particular invention raises the question of what happens when
two people claim to have invented the same thing. For applications filed prior to March 16, 2013,
the first person to invent a particular invention was generally regarded as the inventor and given
priority in obtaining a patent.69 Congress changed that practice, however, when it passed and
President Obama signed the Leahy-Smith America Invents Act (AIA).70 For applications filed on

58 MBO Labs., Inc. v. Becton, Dickinson & Co., 602 F.3d 1306, 1310 n.1 (Fed. Cir. 2010) (“Individuals, not
corporations, create inventions.”); see also Beech Aircraft Corp. v. EDO Corp., 990 F.2d 1237, 1248 (Fed. Cir. 1993)
(“[O]nly natural persons can be ‘inventors.’”).
59 See supra note 40 and accompanying text.
60 35 U.S.C. § 118 (“A person to whom the inventor has assigned or is under an obligation to assign the invention may
make an application for patent.”).
61 In re Application No. 16/524,350, Decision on Petition, 2020 WL 1970052, at *1 (Apr. 22, 2020).
62 Id. DABUS is an acronym for “Device for the Autonomous Bootstrapping of Unified Sentience.” Rebecca Tapscott,
USPTO Shoots Down DABUS’ Bid For Inventorship, IPWATCHDOG (May 4, 2020), at
63 Application No. 16/524,350, 2020 WL 1970052, at *1.
64 Id. at *3.
65 Id. at *3 & n.8 (citing 35 U.S.C. §§ 100(a), 100(g), 115(a)).
66 Id. at *3.
67 Id. at *3-4.
68 EPO Refuses DABUS Patent Applications Designating a Machine Inventor, European Patent Office (Dec. 20, 2019),
69 Leahy-Smith America Invents Act, Pub. L. No. 112-29, § 3(n)(2), 125 Stat. 284, 293 (2011); see also Sanofi-Aventis
v. Pfizer Inc., 733 F.3d 1364, 1366 n.3 (Fed. Cir. 2013).
70 See, e.g., Biogen MA, Inc. v. Japanese Found. for Cancer Rsch., 785 F.3d 648, 654 (Fed. Cir. 2015) (“The AIA
changed the patent system, among other things, from a first-to-invent to a first-inventor-to-file regime for determining
patent priority.”).
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or after March 16, 2013, generally the first person to file his application with the PTO is regarded
as the inventor.71
The Person of Ordinary Skill
Many of the patentability requirements discussed below are analyzed from the perspective of a
“person of ordinary skill in the art” (“POSITA,” sometimes referred to as “a person having
ordinary skill in the art” (PHOSITA), “a person skilled in the art,” and the like).72 For example,
the question whether an invention would have been obvious is analyzed by determining what
would have been known to a person of ordinary skill at the time of the invention under review.73
The person of ordinary skill is a hypothetical construct, not a real person.74 Instead, the person of
ordinary skill is assumed to have the level of education and training common in the field of the
invention, as well as all of the publicly available knowledge in that field.75 Thus, for example, the
legal question in determining whether an invention would have been obvious (and thus ineligible
for patenting) is not whether an invention was in fact obvious to the inventor, but instead whether
the invention would have been obvious to this hypothetical person of ordinary skill.76
Claim Construction
Both a patent’s validity and the determination whether a particular patent is infringed upon may
turn on the meaning and scope of particular patent claim terms.77 For example, the Federal Circuit
has reversed a jury verdict of infringement, and vacated the associated award of $85 million in
damages, based on its conclusion that the trial court applied the incorrect meaning of a single
claim term.78 The process for determining the meaning of a disputed patent claim term is referred
to as claim construction.79

71 Id.
72 See generally MATTHEWS, supra note 22, at 3 § 18:35.
73 35 U.S.C. § 103. See also KSR Int’l Co. v. Teleflex Inc., 550 U.S. 398, 417 (2007).
74 In re Rouffet, 149 F.3d 1350, 1357 (Fed. Cir. 1998) (“Obviousness is determined from the vantage point of a
hypothetical person having ordinary skill in the art to which the patent pertains. This legal construct is akin to the
‘reasonable person’ used as a reference in negligence determinations. The legal construct also presumes that all prior
art references in the field of the invention are available to this hypothetical skilled artisan.” (citation omitted)).
75 Takeda Chem. Indus., Ltd. v. Alphapharm Pty., Ltd., 492 F.3d 1350, 1363 (Fed. Cir. 2007) (stating that a “person of
ordinary skill is a hypothetical person who is presumed to be aware of all the pertinent prior art”) (quoting Custom
Accessories, Inc. v. Jeffrey-Allan Indus., 807 F.2d 955 (Fed. Cir. 1986)).
76 KSR, 550 U.S. at 420 (“The question is not whether the combination was obvious to the patentee but whether the
combination was obvious to a person with ordinary skill in the art.”)
77 MPHJ Tech. Invs., LLC v. Ricoh Ams. Corp., 847 F.3d 1363, 1364 (Fed. Cir. 2017) (“[T]he first step in any validity
analysis is to construe the claims of the invention to determine the subject matter for which patent protection is sought.”
(quoting Smiths Indus. Med. Sys., Inc. v. Vital Signs, Inc., 183 F.3d 1347, 1353 (Fed. Cir. 1999))); Nazomi Commc’ns,
Inc. v. Nokia Corp., 739 F.3d 1339, 1343 (Fed. Cir. 2014) (“The first step of the infringement analysis is claim
construction ....”). See also TVIIM, LLC v. McAfee, Inc., 851 F.3d 1356, 1362 (Fed. Cir. 2017) (“Claim terms must be
construed the same way for the purpose of determining invalidity and infringement.”).
78 SimpleAir, Inc. v. Sony Ericsson Mobile Commc’ns AB, 820 F.3d 419, 421 (Fed. Cir. 2016).
79 Netword, LLC v. Centraal Corp., 242 F.3d 1347, 1352 (Fed. Cir. 2001) (“‘Claim construction’ is the judicial
statement of what is and is not covered by the technical terms and other words of the claims.”). See also Abbott Labs.
v. Sandoz, Inc., 544 F.3d 1341, 1358 (Fed. Cir. 2008) (“The first step in most infringement suits is the procedure called
‘claim construction,’ where the scope of the claim is defined by the court.”); Pall Corp. v. Hemasure Inc., 181 F.3d
1305, 1308 (Fed. Cir. 1999) (“Analysis of patent infringement starts with ‘construction’ of the claim, whereby the court
establishes the scope and limits of the claim, interprets any technical or other terms whose meaning is at issue, and
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There are two standards for determining the proper claim scope. Once a patent has issued, a
patent claim term is given “the meaning that the term would have to a person of ordinary skill in
the art in question at the time of the invention, i.e., as of the effective filing date of the patent
application.”80 This meaning is determined by analyzing evidence intrinsic to the patent (i.e., the
language of the claims, specification, and history of prosecution before the PTO), as well as
extrinsic evidence (e.g., dictionaries or expert testimony) if necessary.81 Because this standard
was clarified by the Federal Circuit sitting en banc in Phillips v. AWH Corp., it is referred to as
the “Phillips standard.”82
If the claim being interpreted is part of a patent application still pending before the PTO,
however, the claim is given its “broadest reasonable construction.”83 The Federal Circuit has
explained that this standard, which is understood to read the patent claims more broadly than
under the Phillips standard,84 applies during examination because the patent applicant can amend
her claims and therefore “has the opportunity and responsibility to remove any ambiguity in claim
term meaning by amending the application.”85
Patent Application Requirements
Claim Clarity
Under 35 U.S.C. § 112(b), the claims appearing at the end of the patent must “particularly point[]
out and distinctly claim[] the subject matter which the inventor or a joint inventor regards as the
invention.”86 This is sometimes referred to as the definiteness requirement.87 Patent claims meet
this requirement by being clear enough to “inform those skilled in the art about the scope of the
invention with reasonable certainty.”88 If a claim fails to meet this standard, it is “indefinite” and
therefore invalid.89 The Supreme Court has described this requirement as “essential” to the quid
pro quo underlying the patent grant; it “enables efficient investment in innovation” because “[a]
patent holder should know what he owns, and the public should know what he does not.”90 The
definiteness requirement thus fosters the “delicate balance the law attempts to maintain between
inventors, who rely on the promise of the law to bring the invention forth, and the public, which

thereby defines the claim with greater precision than had the patentee.”).
80 Phillips v. AWH Corp., 415 F.3d 1303, 1313 (Fed. Cir. 2005) (en banc).
81 Id. at 1313-19.
82 See, e.g., Hamilton Beach Brands, Inc. v. f’real Foods, LLC, 908 F.3d 1328, 1339 n.3 (Fed. Cir. 2018).
83 Phillips, 415 F.3d at 1316 (“The Patent and Trademark Office ... determines the scope of claims in patent
applications not solely on the basis of the claim language, but upon giving claims their broadest reasonable construction
‘in light of the specification as it would be interpreted by one of ordinary skill in the art.’” (quoting In re Am. Acad. of
Sci. Tech. Ctr., 367 F.3d 1359, 1364 (Fed. Cir. 2004))).
84 Celgene Corp. v. Peter, 931 F.3d 1342, 1362 (Fed. Cir. 2019) (“And [inter parte reviews], at the time of these
proceedings, used the broadest reasonable interpretation for claim construction rather than the narrower standard from
Phillips v. AWH Corp., ... used in district court.”).
85 In re Bigio, 381 F.3d 1320, 1324 (Fed. Cir. 2004).
86 35 U.S.C. § 112(b).
87 HZNP Meds. LLC v. Actavis Labs. UT, Inc., 940 F.3d 680, 694 (Fed. Cir. 2019) (describing one of the purposes of
“the definiteness requirement” as “to afford clear notice of what is being claimed so as to apprise the public of what is
still open to them”).
88 Nautilus, Inc. v. Biosig Instruments, Inc., 572 U.S. 898, 910 (2014).
89 See, e.g., Intellectual Ventures I LLC v. T-Mobile USA, Inc., 902 F.3d 1372, 1381 (Fed. Cir. 2018).
90 Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722, 731 (2002).
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should be encouraged to pursue innovations, creations, and new ideas beyond the inventor’s
exclusive rights.”91
Specification Contents
The specification must also meet certain requirements. The specification must provide “a written
description of the invention, and of the manner and process of making and using it,”92 which is
referred to as the written description requirement.93 The written description requirement is met
when the specification “reasonably conveys to those skilled in the art that the inventor had
possession of the claimed subject matter as of the filing date” of the patent.94 Because “the
invention” is defined by the patent claims, the practical analysis is whether the specification
conveys possession of the subject matter of a particular claim or claims.95 The Federal Circuit has
explained that whether an inventor had possession of the invention “requires an objective inquiry
into the four corners of the specification from the perspective of a person of ordinary skill in the
art” and requires the specification to “describe an invention understandable to that skilled artisan
and show that the inventor actually invented the invention claimed.”96 If a patent claim is not
adequately described in the specification, then that claim is invalid.97
The specification must also provide sufficient detail to “enable any person skilled in the art to
which it pertains, or with which it is most nearly connected, to make and use” the invention,98
referred to as the enablement requirement.99 Because, again, the “invention” is defined by the
patent claims, the practical analysis is whether the specification enables a person skilled in the art
to make and use the full scope of a particular claim.100 Thus, the enablement requirement is met
when the specification teaches “those skilled in the art how to make and use the full scope of the
claimed invention without ‘undue experimentation.’”101 If the full scope of a claim is not enabled,
then that claim is invalid.102
The specification must also specify the “the best mode contemplated by the inventor or joint
inventor of carrying out the invention.”103 The best mode requirement means that if inventors
possess a best mode for practicing the invention, they must disclose in the specification
“sufficient information such that one reasonably skilled in the art could practice the best

91 Id.
92 35 U.S.C. § 112(a).
93 Ariad Pharm., Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1340 (Fed. Cir. 2010) (en banc).
94 Rivera v. Int’l Trade Comm’n, 857 F.3d 1315, 1319 (Fed. Cir. 2017) (quoting Ariad, 598 F.3d at 1351).
95 See id.
96 Ariad, 598 F.3d at 1351.
97 See, e.g., Idenix Pharm. LLC v. Gilead Scis. Inc., 941 F.3d 1149, 1164 (Fed. Cir. 2019).
98 35 U.S.C. § 112(a).
99 Ariad, 598 F.3d at 1340.
100 Trustees of Bos. Univ. v. Everlight Elecs. Co., 896 F.3d 1357, 1361-65 (Fed. Cir. 2018).
101 Monsanto Co. v. Syngenta Seeds, Inc., 503 F.3d 1352, 1360 (Fed. Cir. 2007) (quoting In re Wright, 999 F.2d 1557,
1561 (Fed. Cir. 1993)).
102 Everlight, 896 F.3d at 1361-65.
103 35 U.S.C. § 112(a).
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mode.”104 Unlike the written description and enablement requirements, however, claims may not
be held invalid for a failure to disclose the best mode.105
The preceding requirements control the form and content of the disclosure supporting the patent.
The following requirements relate to the claimed invention itself.
Patentable Subject Matter
Section 101 of the Patent Act (Section 101) states that “any new and useful process, machine,
manufacture, or composition of matter, or any new and useful improvement thereof” is patentable
if the invention meets other requirements.106 Despite the seemingly broad scope of this provision,
however, the Supreme Court “has long held that this provision contains implicit exceptions.
Specifically, “‘laws of nature, natural phenomena, and abstract ideas’ are not patentable.”107
To determine whether a patent claim encompasses one of these “judicial exceptions” to
patentability, courts use a two-step test.108 First, the court determines whether the claim is directed
to one of the exceptions.109 If it is, then the court determines whether the claim includes an
“inventive concept” such that the claim is more than just a patent on the abstract idea, law of
nature, or natural phenomena itself.110
The law of patentable subject matter received less attention than the other patent requirements
until about a decade ago, when the Supreme Court began to show renewed interest in the
doctrine.111 Since then, some stakeholders (including a former Chief Judge of the Federal Circuit)
have criticized the Supreme Court and the Federal Circuit for failing to apply the two-step test in
a predictable way, and applying it broadly to inventions that should be eligible for patent
protection.112 The Federal Circuit itself has suggested that Supreme Court revision or
congressional intervention is needed to prevent inventions on important innovations from being
held invalid.113 Last summer, the Senate Committee on the Judiciary’s Subcommittee on
Intellectual Property held three days of hearings on possible legislative revisions to Section
101.114 Petitioners have also asked the Supreme Court to reconsider its patentable subject matter

104 In re Cyclobenzaprine Hydrochloride Extended-Release Capsule Patent Litig., 676 F.3d 1063, 1085 (Fed. Cir.
105 35 U.S.C. § 282(b)(3)(A).
106 Id. § 101.
107 Mayo Collaborative Servs. v. Prometheus Labs., Inc., 566 U.S. 66, 70 (2012).
108 See ChargePoint, Inc. v. SemaConnect, Inc., 920 F.3d 759, 765 (Fed. Cir. 2019).
109 Alice Corp. Pty. v. CLS Bank Int’l, 573 U.S. 208, 217 (2014).
110 Id.
111 For the history of the law of patentable subject matter and its development, see CRS Report R45918, Patent-Eligible
Subject Matter Reform in the 116th Congress
, by Kevin J. Hickey.
112 See, e.g., Paul R. Michel, Reviving and Repairing the American Patent System, 27 FED. CIR. B.J. 263, 277-80
(2018). Paul R. Michel is a former chief judge of the Federal Circuit. Id. at 263 n.a1.
113 See Athena Diagnostics, Inc. v. Mayo Collaborative Servs., LLC, 927 F.3d 1333 (Fed. Cir. 2019) (denying en banc
rehearing of the Section 101 issue, with opinions by eight judges); CRS Legal Sidebar LSB10344, Judges Urge
Congress to Revise What Can Be Patented
, by Kevin T. Richards (discussing the Athena en banc denial in more detail).
114 See Sen. Chris Coons & Sen. Thom Tillis, What Coons and Tillis Learned at Patent Reform Hearings, LAW360
(June 21, 2019), at Video of the hearings and the written testimony are
available online. See The State of Patent Eligibility in America: Part I: Hearing Before the S. Judiciary Comm.,
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jurisprudence in a number of high-profile cases.115 To date, neither the Supreme Court nor
Congress has revised its approach to Section 101.
An applicant also may not receive a patent on something that is not new.116 Thus, if the claimed
invention was, among other things, in public use, on sale, or described in a publication prior to
the filing date of the patent application, then it is ineligible for a patent.117 The requirement that
the invention be different from what came before is referred to as the novelty requirement.118 To
establish a lack of novelty, the PTO examiner (or, in post-issuance proceedings, another party
challenging the patent) relies on the “prior art”—references, such as publications and other
patents, that establish what was known in the art at the time of the applicant’s alleged
invention.119 To demonstrate a lack of novelty (or, in other words, to demonstrate that a patent
claim is “anticipated”), a single reference (usually, a patent or publication) must disclose all of the
limitations in a patent claim.120 Notably, the statutory provision governing novelty states that an
applicant “shall be entitled to a patent unless” the invention is not novel.121 Thus, the statute
places the burden on the PTO to demonstrate that the invention is not novel.122
Under the statute, certain references do not qualify as prior art that would serve to prevent
patenting.123 For example, disclosures by the inventor or a joint inventor made one year or less
before the filing date of the patent application do not qualify as prior art.124 This establishes a one-
year “grace period” for inventors to disclose information regarding the invention without losing
the opportunity to receive a patent.125

Subcomm. on Intellectual Property, 116th Cong. (2019), at
patent-eligibility-in-america-part-i; The State of Patent Eligibility in America: Part II: Hearing Before the S. Judiciary
Comm., Subcomm. on Intellectual Property, 116th Cong. (2019), at
state-of-patent-eligibility-in-america-part-ii; The State of Patent Eligibility in America: Part III: Hearing Before the S.
Judiciary Comm., Subcomm. on Intellectual Property, 116th Cong. (2019), at
115 See, e.g., Athena Diagnostics, Inc. v. Mayo Collaborative Servs., LLC, 915 F.3d 743 (Fed. Cir. 2019), cert. denied,
140 S. Ct. 855 (2020); Ariosa Diagnostics, Inc. v. Sequenom, Inc., 788 F.3d 1371 (Fed. Cir. 2015), cert. denied, 136 S.
Ct. 2511 (2016).
116 See generally 35 U.S.C. § 102.
117 Id.
118 Id.
119 Id.
120 Acoustic Tech., Inc. v. Itron Networked Sols., Inc., 949 F.3d 1366, 1373 (Fed. Cir. 2020) (“In an anticipation
analysis, the dispositive question is whether a skilled artisan would ‘reasonably understand or infer’ from a prior art
reference that every claim limitation is disclosed in that single reference.” (quoting Akamai Techs., Inc. v. Cable &
Wireless Internet Servs., Inc., 344 F.3d 1186, 1192 (Fed. Cir. 2003))).
121 35 U.S.C. § 102.
122 See id.
123 See generally id. § 102(b).
124 Id. § 102(b)(1).
125 Peter Lee, Patents and the University, 63 DUKE L.J. 1, 69 (2013).
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An applicant also may not receive a patent on an invention that is an obvious extension of the
prior art.126 Thus, “if the differences between the claimed invention and the prior art are such that
the claimed invention as a whole would have been obvious before the effective filing date of the
claimed invention,” then the applicant may not receive a patent.127 The Supreme Court has
directed that four factors must be considered when determining whether the prior art renders a
claimed invention obvious:
1. the scope and content of the prior art;
2. the differences between the prior art and the claimed invention;
3. the level of ordinary skill of the art; and
4. any secondary considerations (also referred to as objective indicia) of
Secondary considerations/objective indicia that may be considered in evaluating obviousness
include commercial success, long-felt but unsolved needs, and failure of others, which might
provide evidence regarding whether the invention would have been obvious at the time of
While a single prior art reference is generally used to demonstrate lack of novelty, multiple
references may also be used to establish that a claim would have been obvious.130 Simply
demonstrating that all of the limitations in a claim were disclosed across several references,
however, is insufficient to establish that an invention would have been obvious.131 Instead, the
party challenging the patent must further prove that a person of ordinary skill would have had
some reason to combine the different references.132 For example, a party may argue that a person
of ordinary skill would have had a reason to modify the system disclosed in one reference by
incorporating a part disclosed in another reference.133

126 See 35 U.S.C. § 103.
127 Id.
128 Graham v. John Deere Co. of Kansas City, 383 U.S. 1, 17-18 (1966) (“Under § 103, the scope and content of the
prior art are to be determined; differences between the prior art and the claims at issue are to be ascertained; and the
level of ordinary skill in the pertinent art resolved. Against this background, the obviousness or nonobviousness of the
subject matter is determined. Such secondary considerations as commercial success, long felt but unsolved needs,
failure of others, etc., might be utilized to give light to the circumstances surrounding the origin of the subject matter
sought to be patented.”).
129 Apple Inc. v. Samsung Elecs. Co., 839 F.3d 1034, 1048 (Fed. Cir. 2016) (en banc) (“[E]vidence rising out of the so-
called ‘secondary considerations’ must always when present be considered en route to a determination of obviousness.”
(quoting Transocean Offshore Deepwater Drilling, Inc. v. Maersk Drilling USA, Inc., 699 F.3d 1340, 1349 (Fed. Cir.
130 See, e.g., KSR Int’l Co. v. Teleflex Inc., 550 U.S. 398, 422-26 (2007) (determining that claims would have been
obvious in view of two references).
131 Id. at 418 (“[A] patent composed of several elements is not proved obvious merely by demonstrating that each of its
elements was, independently, known in the prior art.”).
132 Id. at 417-18.
133 Id. at 422-26.
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Maintenance Fees
Although not a prerequisite to receiving a patent, patentees must also pay periodic maintenance
fees (due at 3.5, 7.5, and 11.5 years after issuance) in order to keep their patent in force once it
issues.134 Those fees begin at $1,600 at 3.5 years after issuance, and climb to $7,400 at 11.5 years
after issuance.135 These fees change periodically.136 If a patentee fails to pay the maintenance fees,
then the patent is no longer enforceable.137
Patent Infringement and Enforcement
Although patent rights are granted by the government, the government does not actively protect
those rights once granted; for example, there is no criminal penalty for infringing another’s
patent.138 Instead, the patent owner is responsible for enforcing the patent.139 Often, a patent
owner will sue a party she believes is violating her exclusive rights in federal court.140 Violating
the exclusive rights granted by a patent is referred to as “infringing” a patent.141 This section will
describe patent infringement and related doctrines, before turning to how a patent owner may
attempt to enforce a patent that she believes is being infringed.
Proving Patent Infringement
Patent infringement primarily takes two forms: direct infringement, where a party itself makes,
uses, imports, sells, or offers to sell a patented invention without authorization; and indirect
, where a party in some culpable way causes direct infringement by another.142
Direct Infringement
A party directly infringes a patent by itself making, using, importing, selling, or offering for sale
the claimed invention.143 To determine whether a party infringes, the patent claims are construed

134 HAWES & DOUGLAS, supra note 49, § 24:2.
135 USPTO Fee Schedule, U.S. PAT. & TRADEMARK OFF. (accessed July 9, 2020), at
136 HAWES & DOUGLAS, supra note 49, § 24:2.
137 Id.
138 Dowling v. United States, 473 U.S. 207, 227 (1985) (“Despite its undoubted power to do so, ... Congress has not
provided criminal penalties for distribution of goods infringing valid patents.”); Noel Mendez, Patent Infringers, Come
Out with Your Hands Up!: Should the United States Criminalize Patent Infringement?
, 6 BUFF. INTELL. PROP. L.J. 34,
34-35 (2008) (“In the United States, however, there are no criminal penalties for patent infringement.”).
139 See 35 U.S.C. § 281 (“A patentee shall have remedy by civil action for infringement of his patent.”).
140 Id.
141 Id.
142 A third type of infringement, “artificial infringement,” arises in the context of the specific patent dispute procedure
that Congress developed for resolution of disputes between brand-name and generic pharmaceutical manufacturers. See
discussion infra in “Specialized Dispute Procedures”; see also Richards, supra note 8, at 10-12. Infringement is
“artificial” in those situations because the patent statute defines certain acts as infringing, even though no party has yet
practiced the invention, in order to encourage early resolution of those disputes.
143 35 U.S.C. § 271(a). See also Lifetime Indus., Inc. v. Trim-Lok, Inc., 869 F.3d 1372, 1378 (Fed. Cir. 2017)
(explaining that a party can “make” an invention by assembling separate parts into an infringing combination, as well
as through commercial manufacture); Centillion Data Sys., LLC v. Qwest Commc’ns Int’l, Inc., 631 F.3d 1279, 1284
(Fed. Cir. 2011) (“We hold that to ‘use’ a system for purposes of infringement, a party must put the invention into
service, i.e., control the system as a whole and obtain benefit from it.”); Transocean Offshore Deepwater Drilling, Inc.
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and then compared to the product or method accused of infringement.144 There are two ways a
patentee can prove that an element of an accused product or method meets a patent claim
limitation. First, an element of an accused product or method may exactly match (or “meet”) the
claim limitation. This is referred to as an element “literally” meeting the claim limitation.145 For
example, if the limitation at issue requires a wooden doorknob and the accused product includes a
wooden doorknob, the accused product literally meets the limitation.
An element may also meet a claim limitation under the doctrine of equivalents; in other words,
even if the accused product or method does not literally meet a claim limitation, that limitation
may be met if the accused product or method includes an element that is equivalent to the claim
limitation.146 Under the doctrine of equivalents, an element is equivalent to a claim limitation if it
performs the same function, in the same way, to reach the same result.147 For example, if the
limitation at issue requires a wooden doorknob and the accused product includes a steel
doorknob, the accused product would not literally meet that claim limitation, but might meet the
limitation under the doctrine of equivalents.
Indirect Infringement
Indirect infringement refers to conduct where a party does not itself directly infringe a patent, but
causes another party to infringe directly.148 There are two main types of indirect infringement:
induced infringement and contributory infringement.149
Induced Infringement
Under the patent statute, “[w]hoever actively induces infringement of a patent shall be liable as an
infringer.”150 To induce infringement, a party must take an affirmative action to encourage another
to perform direct infringement of a patent, knowing that those actions would constitute

v. Maersk Contractors USA, Inc., 617 F.3d 1296, 1311 (Fed. Cir. 2010) (“A ‘sale’ is not limited to the transfer of
tangible property; a sale may also be the agreement by which such a transfer takes place.”); 3D Sys., Inc. v. Aarotech
Labs., Inc., 160 F.3d 1373, 1379 (Fed. Cir. 1998) (holding that “price quotation letters” were an offer to sell).
144 Cordis Corp. v. Bos. Sci. Corp., 658 F.3d 1347, 1354 (Fed. Cir. 2011) (“The infringement analysis is a two step
inquiry. ‘First, the court determines the scope and meaning of the patent claims asserted, and then the properly
construed claims are compared to the allegedly infringing device.’” (quoting Cybor Corp. v. FAS Techs., Inc., 138 F.3d
1448, 1454 (Fed. Cir. 1998) (en banc) (internal citations omitted))).
145 E.I. du Pont De Nemours & Co. v. Unifrax I LLC, 921 F.3d 1060, 1073 (Fed. Cir. 2019) (“For literal infringement,
the patentee must prove that the accused product meets all the limitations of the asserted claims; if even one limitation
is not met, there is no literal infringement.”).
146 Warner-Jenkinson Co. v. Hilton Davis Chem. Co., 520 U.S. 17, 21 (1997) (explaining that under the doctrine of
equivalents, “a product or process that does not literally infringe upon the express terms of a patent claim may
nonetheless be found to infringe if there is ‘equivalence’ between the elements of the accused product or process and
the claimed elements of the patented invention”).
147 Plastic Omnium Advanced Innovation & Rsch. v. Donghee Am., Inc., 943 F.3d 929, 938 (Fed. Cir. 2019) (“A
finding of infringement under the doctrine of equivalents requires a showing that the difference between the claimed
invention and the accused product or method was insubstantial or that the accused product or method performs the
substantially same function in substantially the same way with substantially the same result as each claim limitation of
the patented product or method.” (quoting AquaTex Indus., Inc. v. Techniche Sols., 479 F.3d 1320, 1326 (Fed. Cir.
148 See Lifetime Indus., 869 F.3d at 1377-80.
149 Id. at 1379-80.
150 35 U.S.C. § 271(b).
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infringement.151 Thus, a finding of induced infringement requires proof that “(1) a third party
directly infringed the asserted claims of the ... patents; (2) [the defendant] induced those
infringing acts; and (3) [the defendant] knew the acts it induced constituted infringement.”152
Contributory Infringement
Broadly speaking, contributory infringement bars selling or importing a material component of a
patented invention, where the component has no substantial noninfringing use.153 To prove
contributory infringement, a patent owner must prove (1) “that there is direct infringement”;
(2) “that the accused infringer had knowledge of the patent”; (3) “that the component has no
substantial noninfringing uses”; and (4) “that the component is a material part of the
Enforcing a Patent
Patent owners can enforce their patents in two main ways. First, the patent owner may file a civil
action in a federal district court alleging direct or indirect patent infringement.155 Second, if the
patent owner believes that another party is importing articles that infringe its patent, it may file a
complaint in the International Trade Commission.156
District Court Enforcement
The primary method of patent enforcement is to file a civil action in federal district court. The
process begins when a patent owner files a complaint alleging that another person has infringed
its patent.157 Generally speaking, the three primary issues in district court litigation will be claim
, infringement, and validity. For claim construction, the parties will litigate any
disputed patent claim constructions—that is, the manner in which a patent claim is interpreted—
and the assigned judge will issue an order ruling how the disputed claim terms will be
construed.158 Following claim construction by the judge, whether the accused product(s) infringe
the patent claims, as construed by the judge, is generally tried to a jury.159

151 Limelight Networks, Inc. v. Akamai Techs., Inc., 572 U.S. 915, 920 (2014) (holding that induced infringement
requires direct infringement); Glob.-Tech Appliances, Inc. v. SEB S.A., 563 U.S. 754, 766 (2011) (“[I]nduced
infringement under § 271(b) requires knowledge that the induced acts constitute patent infringement.”); Power
Integrations, Inc. v. Fairchild Semiconductor Int’l, Inc., 843 F.3d 1315, 1332 (Fed. Cir. 2016).
152 Power Integrations, 843 F.3d at 1332.
153 See 35 U.S.C. § 271(c) (“Whoever offers to sell or sells within the United States or imports into the United States a
component of a patented machine, manufacture, combination or composition, or a material or apparatus for use in
practicing a patented process, constituting a material part of the invention, knowing the same to be especially made or
especially adapted for use in an infringement of such patent, and not a staple article or commodity of commerce
suitable for substantial noninfringing use, shall be liable as a contributory infringer.”).
154 Fujitsu Ltd. v. Netgear Inc., 620 F.3d 1321, 1326 (Fed. Cir. 2010).
155 28 U.S.C. § 1338.
156 19 U.S.C. § 1337(a)(1)(B)-(E).
157 See, e.g., Lifetime Indus., Inc. v. Trim-Lok, Inc., 869 F.3d 1372, 1375 (Fed. Cir. 2017).
158 Markman v. Westview Instruments, Inc., 517 U.S. 370, 372 (1996) (“We hold that the construction of a patent,
including terms of art within its claim, is exclusively within the province of the court.”).
159 See Apple Inc. v. Samsung Elecs. Co., 839 F.3d 1034, 1040 (Fed. Cir. 2016) (en banc) (reviewing jury verdict of
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In defense, the party accused of infringement may argue that the patent did not, in fact, meet the
statutory requirements for patenting when it issued. This is referred to as an argument that the
patent is “invalid.”160 Because an invalid patent is not legally enforceable, a judgment that the
patent is invalid will lead to a finding of no liability.161 The issue of invalidity is also typically
tried to a jury.
If the jury finds that the patent is infringed and not invalid, then the patent owner is entitled to a
remedy. Available remedies include money damages and a court order that the infringer cease
infringement (an “injunction”).162 The minimum amount of money damages is a “reasonable
royalty,”163 generally set at the amount that the parties would have agreed to for the infringer to
license the patent at the time infringement began.164 In certain circumstances, the patent owner
may also be entitled to recover any profits she can prove were lost due to the infringement.165 If
the infringing behavior was “egregious,” moreover, then the damages award may be increased up
to triple the amount awarded by the jury.166 To receive an injunction, a patentee must prove
(1) that it has suffered an irreparable injury; (2) that monetary damages are inadequate to
compensate for that injury; (3) that the balance of hardships favors an injunction; and (4) that an
injunction is in the public interest.167
In “exceptional” cases, the trial judge may also, in her discretion, award the prevailing party its
attorney’s fees.168 The Supreme Court has held that an exceptional case is one that “stands out
from others with respect to the substantive strength of a party’s litigating position (considering
both the governing law and the facts of the case) or the unreasonable manner in which the case
was litigated.”169
International Trade Commission Enforcement
The U.S. International Trade Commission (ITC)—an independent federal agency—administers
Section 337 of the Tariff Act of 1930 (Section 337), among other statutes, which allows it to
“investigate and issue decisions on unfair methods of competition and unfair acts in the
importation and/or sale of imported articles.”170 Section 337 establishes that the importation into,
or sale within the United States of articles that infringe a valid U.S. patent, copyright, or
trademark are unlawful actions the ITC may address.171 Although Section 337 investigations are

160 35 U.S.C. § 282(b).
161 Viskase Corp. v. Am. Nat. Can Co., 261 F.3d 1316, 1323 (Fed. Cir. 2001) (“[A]n invalid claim can not be infringed
....” (quoting Richdel, Inc., v. Sunspool Corp., 714 F.2d 1573, 1580 (Fed. Cir. 1983))). See also Commil USA, LLC v.
Cisco Sys., Inc., 135 S. Ct. 1920, 1929 (2015) (“To say that an invalid patent cannot be infringed, or that someone
cannot be induced to infringe an invalid patent, is in one sense a simple truth, both as a matter of logic and semantics.”)
162 35 U.S.C. §§ 281 (remedies generally), 283 (injunction), 284 (damages).
163 Id. § 284.
164 See, e.g., Power Integrations, Inc. v. Fairchild Semiconductor Int’l, Inc., 904 F.3d 965, 977 (Fed. Cir. 2018).
165 Mentor Graphics Corp. v. EVE-USA, Inc., 851 F.3d 1275, 1283 (Fed. Cir. 2017).
166 Halo Elecs., Inc. v. Pulse Elecs., Inc., 136 S. Ct. 1923, 1931 (2016).
167 eBay Inc. v. MercExchange, L.L.C., 547 U.S. 388, 391 (2006).
168 35 U.S.C. § 285.
169 Octane Fitness, LLC v. ICON Health & Fitness, Inc., 572 U.S. 545, 554 (2014).
170 William P. Atkins & Justin A. Pan, An Updated Primer on Procedures and Rules in 337 Investigations at the U.S.
International Trade Commission
, 18 U. BALT. INTELL. PROP. L.J. 105, 106-07 (2010).
171 19 U.S.C. § 1337(a)(1)(B)-(E).
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not limited to behavior arising from IP, in recent years many such investigations “have focused on
either patent, unregistered trademark, or trade secret claims.”172
Section 337 investigations are somewhat similar to civil infringement actions in district court,
with some important differences. Unlike infringement actions in district court, where the court
primarily adjudicates disputes between the parties, in Section 337 investigations the ITC itself
investigates whether there were unfair methods of competition or unfair acts in importation.173
Thus, an investigative attorney from the ITC’s Office of Unfair Import Investigations participates
as a party in the process, along with the complainant and respondent.174
Moreover, in order to be entitled to relief, the party who files the Section 337 complaint “must
show that a U.S. industry that is dedicated to exploitation of the asserted IP rights either exists or
is in the process of being established.”175 To meet this domestic industry requirement, a
complainant must establish that she is performing activities based in the United States that exploit
the particular IP rights (the “technical element”) and that she has significant investment in
exploitation of the IP rights (the “economic element”).176
Section 337 investigations are evaluated based on the complaint filed by a private party.177 First,
the ITC performs a pre-institution investigation to determine whether the complaint provides an
adequate basis for a full investigation.178 If the ITC determines that the complaint establishes such
a basis, then a full investigation begins and is overseen by an administrative law judge (ALJ).179
Following this process, the ALJ issues an initial determination whether a violation of Section 337
has been shown; that determination may be reviewed by the ITC Commissioners, and the
Commissioners’ determination may then be appealed to the Federal Circuit.180
If a Section 337 violation is established, possible remedies include (1) a general exclusion order,
which forbids importation of products regardless of the source; (2) a limited exclusion order,
which forbids importation of those products by specific companies designated in the complaint;
(3) cease-and-desist orders that enjoin activities by U.S. entities; (4) temporary exclusion or
cease-and-desist orders during the pendency of the investigation; and (5) consent orders, where
the parties agree to an outcome.181 The U.S. President may disapprove any exclusion or cease-
and-desist order within sixty days of issuance; if he does not, then the order goes into effect.182

172 Atkins & Pan, supra note 170, at 107 (“The majority of Section 337 investigations have focused on either patent,
unregistered trademark, or trade secret claims, in part because these types of rights are not subject to recordation with
the U.S. Customs Service.”). While most recent cases have involved allegations of patent infringement, the ITC has
also adjudicated cases involving alleged trademark infringement or dilution, trade dress misappropriation and
infringement, false designation of origin, copyright infringement, and misappropriation of trade secrets, among others.
Id. at 108-09 (collecting cases).
173 19 U.S.C. § 1337(b); 19 C.F.R. §§ 210.9-210.10.
174 Atkins & Pan, supra note 170, at 116. See also 19 C.F.R. § 210.3.
175 Atkins & Pan, supra note 170, at 120 (citing 19 U.S.C. § 1337(a)(2)).
176 Id. at 121; see, e.g., InterDigital Commc’ns, LLC v. ITC, 707 F.3d 1295, 1298 (Fed. Cir. 2013); 19 U.S.C.
§ 1337(a)(3).
177 Atkins & Pan, supra note 170, at 112; 19 C.F.R. § 210.8.
178 Atkins & Pan, supra note 170, at 112; 19 C.F.R. § 210.9.
179 Atkins & Pan, supra note 170, at 113; 19 U.S.C. § 1337(b).
180 Atkins & Pan, supra note 170, at 113.
181 Id. at 129-33.
182 Id. at 135 (citing 19 U.S.C. § 1337(j)). Such disapprovals are reportedly rare. Id.
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Specialized Dispute Procedures for Certain Pharmaceuticals
Congress has also implemented several specialized procedures for certain pharmaceutical patent
disputes, with the general goal of encouraging early resolution of disputes relating to market entry
of small-molecule drugs and large-molecule biological products (i.e., “biologics”).183 Generally,
these disputes are between brand-name drug and biological product manufacturers (the brands),
whose products are generally protected by patents, and generic drug or biosimilar manufacturers
(the generics), which market competing pharmaceuticals once the brands’ products are no longer
protected by patents. The procedures differ depending on whether the pharmaceutical is regulated
as a drug or as a biologic.184
The Hatch-Waxman Act governs the dispute process for small-molecule drugs.185 In order to
market a new drug, the manufacturer must submit and the Food and Drug Administration (FDA)
must approve a new drug application (NDA). The NDA must demonstrate, among other things,
that the drug is safe and effective for its intended use, and must list any patents claiming the drug
or method of using the drug that could reasonably be asserted in infringement litigation.186 A
generic drug manufacturer may later file an abbreviated new drug application (ANDA) that relies
on the FDA’s approval of a drug with the same active ingredient (the “reference listed drug,” or
RLD) to establish safety and efficacy.187 The ANDA may also certify that the RLD is either not
protected by patents or that applicable patents are invalid and/or not infringed.188 Under certain
circumstances, patent law treats the filing of an ANDA as an “artificial” act of patent
infringement,189 allowing for the resolution of patent disputes (for example, whether any patent
covering the RLD is invalid) before the generic product is marketed to the public. If the brand
manufacturer sues the generic manufacturer within forty-five days following the generic’s ANDA
filing, FDA generally cannot approve the ANDA for thirty months while the parties litigate the
patent dispute—a period often referred to as the “thirty-month stay.”190
The Biologics Price Competition and Innovation Act of 2009 (BPCIA) governs the dispute
resolution procedure for biologics and biosimilars.191 In order to market a biologic, a
manufacturer must submit and FDA must approve a biologics license application (BLA). Under
the BPCIA, a biosimilar manufacturer may rely on a sufficiently similar, already licensed biologic
(the “reference product”) when applying for a manufacturing license. Unlike Hatch-Waxman,
however, regulatory approval of biologics is not directly contingent on the parties’ resolution of

183 Often, new pharmaceuticals are marketed under patent protection by brand-name manufacturers of drugs and
biologics. These specialized procedures are also designed to encourage follow-on production of competing (generally
less expensive) generic drugs and products that are biosimilar to the biologics. See generally CRS Report R45666,
Drug Pricing and Intellectual Property Law: A Legal Overview for the 116th Congress, coordinated by Kevin J.
Hickey, at 27-35.
184 For a summary comparison, see CRS In Focus IF11214, Drug Pricing and the Law: Pharmaceutical Patent
, by Kevin J. Hickey.
185 Drug Price Competition and Patent Term Restoration Act of 1984, Pub. L. No. 98-417, 98 Stat. 1585 (1984) (Hatch-
Waxman Act) (codified as amended at 21 U.S.C. §355 and 35 U.S.C. §156, 271 and 282).
186 21 U.S.C. § 355(d).
187 Pub. L. No. 98-417, § 101, 98 Stat. 1585.
188 35 U.S.C. § 355(j)(2)(A)(vii)(I)-(IV).
189 See Eli Lilly & Co. v. Medtronic, Inc., 496 U.S. 661, 676 (1990); 35 U.S.C. § 271(e)(2)-(6). The “artificial” act of
infringement (filing an application with FDA) is distinguished from traditional direct patent infringement—making,
using, selling, or importing the patented invention. See 35 U.S.C. § 271(a).
190 See 35 U.S.C. § 271(a); Caraco Pharm. Labs., Ltd. v. Novo Nordisk A/S, 566 U.S. 399, 407-08 (2012).
191 Pub. L. No. 111-148, tit. VII, 124 Stat. 199, 804-21 (2010).
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any patent disputes. Instead, biosimilar patent disputes may be resolved through the BPCIA’s
“patent dance,” “a carefully calibrated scheme for preparing to adjudicate, and then adjudicating,
claims of infringement.”192 After the biosimilar manufacturer submits its application with FDA,
the biosimilar applicant and reference product manufacturer may exchange information regarding
the patents that each party believes are relevant along with related positions on infringement and
validity.193 Depending on the extent of their participation in this information exchange, each party
may have the opportunity to litigate the patents at the conclusion of the patent dance, or later on,
when the biosimilar is marketed.194 Injunctive relief to compel the biosimilar applicant to engage
in the patent dance is unavailable under federal law.195
Patent Invalidation and Cancellation
As explained above, PTO examines patent applications for compliance with the various statutory
requirements before allowing patents to issue.196 If it is later determined that an issued patent did
not meet those requirements, the patent is held invalid and cannot be enforced.197 There are two
primary fora in which an issued patent can be invalidated or cancelled: (1) through district court
litigation; or (2) through specialized administrative proceedings before the PTO.
District Court Litigation
A common defense to an allegation of patent infringement is that the patent is invalid and should
not have been issued because it did not meet the requirements for patenting.198 For example, an
accused infringer may claim that the patented invention was not actually novel or that the patent
claims are indefinite. Because issued patents are presumed to be valid,199 facts surrounding
invalidity must be proven by clear and convincing evidence—a higher burden than the
preponderance-of-the-evidence standard generally used in civil litigation.200
An accused infringer may also argue that the patent is unenforceable due to “inequitable conduct”
during patent prosecution before the PTO.201 Inequitable conduct occurs when the patentee, in the
course of prosecuting the patent, acts “with the specific intent to deceive the PTO” and that, but
for that deception, the PTO would not have allowed the patent to issue.202 For example, “[i]n a
case involving nondisclosure of information, clear and convincing evidence must show that the
applicant made a deliberate decision to withhold a known material reference.”203

192 Sandoz Inc. v. Amgen Inc., 137 S. Ct. 1664, 1670 (2017); 42 U.S.C. § 262(l).
193 Sandoz, 137 S. Ct. at 1671-72.
194 Id. at 1672.
195 Id. at 1675. Rather, the exclusive remedy for the biosimilar applicant’s failure to commence the patent dance is
provided by 42 U.S.C. § 262(l)(9)(C), which provides that, in that situation, “the reference product sponsor, but not the
[biosimilar] applicant, may bring an action under section 2201 of title 28 for a declaration of infringement, validity, or
enforceability of any patent that claims the biological product or a use of the biological product.” Id.
196 See discussion supra in “Patent Requirements.
197 35 U.S.C. § 282(b).
198 See discussion supra in “District Court Enforcement.”
199 35 U.S.C. § 282.
200 Microsoft Corp. v. i4i Ltd. P’ship, 564 U.S. 91, 95 (2011).
201 Therasense, Inc. v. Becton, Dickinson & Co., 649 F.3d 1276, 1290 (Fed. Cir. 2011) (en banc).
202 Id.
203 Id. (quoting Molins PLC v. Textron, Inc., 48 F.3d 1172, 1181 (Fed. Cir. 1995)).
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PTO Administrative Proceedings
Congress has also enacted a number of specialized administrative proceedings for reviewing and
potentially cancelling issued patents.204
Ex Parte Reexamination
“Any person at any time” may file a request for the PTO to reexamine an issued patent.205 The
request must be based on “patents or printed publications which that person believes to have a
bearing on the patentability of any claim of a particular patent.”206 If the PTO Director determines
that the request raises “a substantial new question of patentability affecting any claim of the
patent,” then she may institute an ex parte reexamination.207 If a reexamination is initiated, it
proceeds in the same manner as the initial examination; in other words, the examiner may reject
the claims on the basis of the new prior art, the applicant may amend the claims, etc.208 As in
initial examination, claim terms are given their broadest reasonable construction consistent with
the specification.209 Unlike other methods of post-issuance review, however, the person who
sought reexamination is not involved in the process once the PTO decides to initiate
Post-Grant Review
As part of the AIA’s major changes to the patent regime in 2011, Congress also created post-grant
review (PGR), an administrative proceeding that can result in cancellation210 of an issued
patent.211 Within nine months after a patent issues,212 anyone other than the patent holder may file
a petition with the PTO requesting the PTO to initiate PGR to review the validity of the patent.213
The petition may request review of the patent based on any of the requirements for patenting.214
For example, the petition may argue that the patent is not directed to patentable subject matter
under Section 101; that the claims are indefinite under Section 112; or that the claims would have
been obvious under Section 103.215

204 These proceedings have been upheld over constitutional challenges arguing that patents can be invalidated only by a
federal court. Oil States Energy Servs., LLC v. Greene’s Energy Grp., LLC, 138 S. Ct. 1365, 1370 (2018); Patlex Corp.
v. Mossinghoff, 758 F.2d 594, 596 (Fed. Cir. 1985).
205 35 U.S.C. § 302.
206 Id. § 301.
207 Id. § 303(a). The PTO Director may also determine whether a substantial new question of patentability exists on her
own initiative. Id.
208 Id. § 305. For more detail regarding initial examination, see discussion supra in “Patent Requirements.”
209 In re Man Mach. Interface Techs. LLC, 822 F.3d 1282, 1286 (Fed. Cir. 2016) (“In reexamination, claims are given
their broadest reasonable interpretation (“BRI”) consistent with the specification.”).
210 Although the terminology is different, there is no practical difference between a district court invalidating a claim
during litigation and the PTO cancelling a claim following an administrative proceeding. The result is the same: the
patent can no longer be enforced.
211 35 U.S.C. §§ 321-29.
212 Id. § 321(b).
213 Id. § 321(a).
214 Id. § 282(b).
215 Id.
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Although the PTO’s Patent Trial and Appeal Board (PTAB) applied the “broadest reasonable
construction” standard for some time,216 the PTAB now applies the Phillips standard for claim
construction.217 After a PGR petition is filed, the patent owner may file a preliminary response
arguing that the patent claims meet all patenting requirements.218 Based on the petition and any
response, the PTO Director determines whether “it is more likely than not that at least 1 of the
claims challenged in the petition is unpatentable.”219 If so, the PTAB may institute review.220 The
PTAB may also institute review if the petition “raises a novel or unsettled legal question that is
important to other patents or patent applications.”221 The PTAB’s decision whether to institute
review may not be appealed.222
If the PTAB institutes review, the patent owner may file a full response to the petition; the
petitioner may file a reply; and, generally, the patent owner may file a sur-reply.223 The patent
owner may also file a motion to amend the claims.224 Following the sur-reply, the PTAB holds a
hearing where the petitioner and patent owner present arguments regarding whether the patent
meets the relevant requirements for patenting.225 Following the hearing, the PTAB issues a final
written decision determining whether the patent is valid.226 The final written decision may be
appealed to the Federal Circuit.227 If, after all appeals, the patent claims are held invalid, then the
PTO issues a certificate cancelling those claims.228
Inter Partes Review
Inter partes review (IPR) is another administrative proceeding introduced in the AIA, and the
most-used PTO proceeding by an overwhelming margin.229 The process for IPR is nearly

216 Cuozzo Speed Techs., LLC v. Lee, 136 S. Ct. 2131, 2139 (2016).
217 Personalized Media Commc’ns, LLC v. Apple Inc., 952 F.3d 1336, 1340 n.2 (Fed. Cir. 2020) (“Per recent
regulation, the Board applies the Phillips claim construction standard to IPR petitions filed on or after November 13,
2018. See Changes to the Claim Construction Standard for Interpreting Claims in Trial Proceedings Before the Patent
Trial and Appeal Board
, 83 Fed. Reg. 51,340 (Oct. 11, 2018) (codified at 37 C.F.R. § 42.100(b)). Because Apple filed
its IPR petition before November 13, 2018, we apply the broadest reasonable interpretation standard.”).
218 35 U.S.C. § 323.
219 Id. § 324(a). The PTO Director has delegated this authority to PTAB. 37 C.F.R. § 42.4 (“The Board institutes the
trial on behalf of the Director.”); Thryv, Inc v. Click-To-Call Techs., LP, 140 S. Ct. 1367, 1371 (2020) (“The Director
has delegated institution authority to the Patent Trial and Appeal Board.”).
220 35 U.S.C. § 324(a). Notably, the decision whether to institute is permissive, rather than mandatory. Id. (stating that
“the director may not institute” PGR “unless” the petitioner demonstrates that it is more likely than not that at least one
claim is unpatentable, but not mandating institution (emphasis added)).
221 Id. § 324(c).
222 Id. § 324(e); Thryv, 140 S. Ct. at 1372-74; Cuozzo Speed Techs., LLC v. Lee, 136 S. Ct. 2131, 2139 (2016). See
CRS Legal Sidebar LSB10454, No Judicial Review of Certain Patent Office Decisions, Supreme Court Holds, by
Kevin T. Richards.
223 Patent Trial and Appeal Board Consolidated Trial Practice Guide, U.S. PAT. & TRADEMARK OFF. (Nov. 2019), at See also 35 U.S.C. § 326(a) (giving PTO Director the
power to promulgate regulations governing PGR).
224 35 U.S.C. § 326(a)(9).
225 See id. § 326(a)(10).
226 Id. § 328(a).
227 Id. § 329.
228 Id. § 328(b).
229 Trial Statistics, U.S. PAT. & TRADEMARK OFF. (June 2019), at
Trial_Statistics_2019-06-30.pdf (stating that IPR petitions account for 93% of all administrative proceeding petitions).
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identical to PGR, with two primary differences.230 The first difference is the time window for
filing an IPR. Whereas a PGR must be filed within the first nine months after a patent issues,231
an IPR may be filed only after the later of nine months after the patent issues (and when any PGR
regarding the patent concludes) through the time the patent expires.232
The second difference is the grounds for cancellation that may be presented in an IPR. Whereas a
PGR petition may challenge whether a patent claim meets any of the patenting requirements, an
IPR may challenge a patent claim only on the basis of anticipation (Section 102) or obviousness
(Section 103), and may rely only on prior art patents or printed publications (and not other forms
of prior art, such as public uses).233 Procedurally, however, IPR is the same as PGR: a person
(other than a patent’s owner) files a petition; the patent owner may file a preliminary response;
and the PTAB decides whether to initiate IPR.234 If IPR is instituted, the patent owner files a
response; the petitioner files a reply; the patent owner files a sur-reply; and the PTAB holds a
hearing on the issues.235 The PTAB then issues a final written decision, which may be appealed to
the Federal Circuit.236
Covered Business Method Review
The AIA also introduced cover business method review (CBM), a time-limited administrative
proceeding for reviewing patents relating to methods of doing business.237 CBM review follows
many of the same procedures as PGR,238 with several differences. A CBM review petition may be
filed only by a party who “has been sued for infringement of the patent or has been charged with
infringement under that patent” and may be filed only against a patent that is the subject of the
suit.239 Moreover, the patent must claim a “covered business method,” which the statute defines as
“a method or corresponding apparatus for performing data processing or other operations used in
the practice, administration, or management of a financial product or service, except that the term
does not include patents for technological inventions.”240 The CBM review program will sunset
on September 16, 2020, absent congressional extension.241
Comparison of PTO Proceedings
Table 1 summarizes the four methods of challenging patents administratively at the PTO:

230 Another difference is that the standard for instituting IPR is “that there is a reasonable likelihood that the petitioner
would prevail with respect to at least 1 of the claims challenged in the petition,” 35 U.S.C. § 314(a), instead of PGR’s
standard of “that it is more likely than not that at least 1 of the claims challenged in the petition is unpatentable,” id.
§ 324(a).
231 Id. § 321(c).
232 Id. § 311(c).
233 Id. § 311(b).
234 Id. § 312-14, 316, 318.
235 Id. § 318.
236 Id. § 319.
237 Leahy-Smith America Invents Act, Pub. L. No. 112-29, 125 Stat. 331, § 18(a) (2011).
238 Id. § 18(a)(1)(A).
239 Id. § 18(a)(1)(B).
240 Id. § 18(d)(1).
241 Id. § 18(a)(3).
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Table 1. PTO Post-Issuance Proceedings
Ex Parte
Novelty or
Substantial new
including the
nonobviousness on the
question of
PTO Director
basis of patents or
on his/her own printed publications.245
Nine months
Anyone except Patent-eligible subject
More likely than None.
after issuance
the patent
matter; novelty;
not that at least
or reissuance
one of the
of a patent.247
indefiniteness; written
patent claims is
The later of
Anyone except Novelty or
(1) nine
the patent
nonobviousness on the
likelihood that
months after
basis of patents or
the petitioner
patent grant;
printed publications.253
would prevail
with respect to
(2) termination
at least one of
of any PGR.251
the challenged

242 35 U.S.C. § 302 (“Any person at any time may file a request for reexamination ....”).
243 Id.
244 Id. § 303(a).
245 Id. § 302 (“Any person at any time may file a request for reexamination by the [PTO] of any claim of a patent on the
basis of any prior art cited under the provisions of section 301.”); id. § 301 (allowing any person at any time to cite
“prior art consisting of patents or printed publications which that person believes to have a bearing on the patentability
of any claim of a particular patent”).
246 Id. § 303(a).
247 Id. § 321(c).
248 Id. § 321(a) (“[A] person who is not the owner of a patent may file with the [PTO] a petition to institute a post-grant
review of the patent.”).
249 Id. § 321(b); id. § 282(b)(2), (3).
250 Id. § 324(a).
251 Id. § 311(c).
252 Id. § 311(a) (“[A] person who is not the owner of a patent may file with the [PTO] a petition to institute an inter
partes review of the patent.”).
253 Id. § 311(b) (“A petitioner in an inter partes review may request to cancel as unpatentable 1 or more claims of a
patent only on a ground that could be raised under section 102 or 103 and only on the basis of prior art consisting of
patents or printed publications.”).
254 Id. § 314(a).
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None (other
A person or
May challenge only a
More likely than Sept. 16,
than sunset
the person’s
covered business
not that at least
real party in
method patent.257 May
one of the
interest or
raise patent-eligible
privy who has
subject matter; novelty;
claims is
been sued or
charged with
indefiniteness; written
description; or
under the
enablement issues. If
challenging a pre-AIA
patent, may rely only on
certain types of prior
Source: Created by CRS based on Title 35 of the U.S. Code.
Considerations for Congress
Just as the Supreme Court has seemingly taken an increased interest in patent law in recent years,
as indicated by the rise in the number of patent law cases for which it has granted certiorari,261
Congress has also recently enacted several major patent reforms. Congress enacted the AIA in
2011, which introduced a number of new administrative procedures for challenging patents and
restructured the substantive patent laws.262 Congress also enacted specialized procedures
governing patent disputes involving drugs (the Hatch-Waxman Act)263 and biologics (BPCIA).264
To the extent that Congress wishes to further reform the law governing patents, it could do so
under the powers granted to it in the Constitution.265 Indeed, various reforms have been proposed
over the past several years.
For example, Congress could modify the patentable subject matter requirement under Section
101. As explained above,266 some stakeholders have criticized the Supreme Court and Federal

255 Pub. L. No. 112-29, 125 Stat. 331, § 18(a)(1), (a)(1)(A) (2011) (stating that CBM proceedings will be governed by
the PGR procedures, except that the § 321(c) deadline for filing does not apply).
256 Id. § 18(a)(1)(B).
257 Id. § 18(a)(1)(E); id. § 18(d)(1) (defining a “covered business method patent” as “a patent that claims a method or
corresponding apparatus for performing data processing or other operations used in the practice, administration, or
management of a financial product or service, except that the term does not include patents for technological
258 Id. § 18(a)(1)(C).
259 Id. § 18(a)(1); 35 U.S.C. § 324(a).
260 Pub. L. No. 112-29, 125 Stat. 331, § 18(a)(3) (2011).
261 See discussion supra in note 46 and accompanying text.
262 See generally id.
263 Pub. L. No. 98-417, 98 Stat. 1585 (1984).
264 Pub. L. No. 111-148, tit. VII, 124 Stat. 199, 804-21 (2010).
265 U.S. CONST. art. I, § 8, cl. 8 (empowering Congress to “promote the Progress of Science and useful Arts, by securing
for limited Times to ... Inventors the exclusive Right to their respective ... Discoveries”).
266 See discussion supra in “Patentable Subject Matter.”
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Circuit for allegedly not applying the governing two-step test in a predictable manner,267 and
some judges on the Federal Circuit have suggested that reform is necessary.268 Although potential
draft language was circulated before the three days of hearings on Section 101 last summer,269
ultimately no bill was introduced.
PTAB administrative reviews are another area of potential and proposed reform. For example, the
proposed Support Technology and Research for Our Nation’s Growth and Economic Resilience
Patents Act of 2019 (STRONGER Patents Act; S. 2082) would make it harder to invalidate
patents in PTAB proceedings by applying the presumption of validity and increasing the burden
of proof, among other changes.270 Conversely, other stakeholders argue that recent changes in
PTAB procedures have made it too difficult to invalidate patents and thus undermine the purpose
of those reviews.271 Those stakeholders urge Congress to examine the frequency with which the
PTAB exercises its discretion to deny administrative review without addressing the merits of the
Other reforms are aimed at addressing perceived misuses of the patent system by various entities.
For example, the proposed Advancing America’s Interests Act (H.R. 8037) aims to “modernize
the ITC process”273 by, among other things, limiting the scope of activities that meet the domestic
industry requirement for invoking ITC jurisdiction.274 According to one sponsor, this will ensure
that the ITC “is not misused by patent licensing entities.”275 As another example, there have been
several proposals in the 116th Congress to address alleged misuse of the patent system by
pharmaceutical manufacturers.276
As technologies grow and change, additional areas of patent law may interest Congress and may
prove ripe for reform. For example, if use of AI devices continues to rise, Congress could
overturn the PTO’s decision that AI devices may not be listed as inventors on patent
applications.277 Whatever changes occur, the importance of patents and IP to the American
economy suggests that patent law will remain an area of interest and activity in the years to come.

267 See, e.g., Michel, supra note 112, at 277-80.
268 See Athena Diagnostics, Inc. v. Mayo Collaborative Servs., LLC, 927 F.3d 1333 (Fed. Cir. 2019) (denying en banc
rehearing of the Section 101 issue, with opinions by eight judges); Richards, supra note 113.
269 Press Release, Office of Senator Thom Tillis, Sens. Tillis and Coons and Reps. Collins, Johnson, and Stivers
Release Draft Bill Text to Reform Section 101 of the Patent Act
(May 22, 2019), at
270 Support Technology and Research for Our Nation’s Growth and Economic Resilience Patents Act of 2019, H.R.
3666, 116th Cong. (2019).
271 Britain Eakin, Congress Urged To Probe ‘Badly Misguided’ PTAB Denials, LAW360 (June 30, 2020), at
272 Id.
273 Press Release, Office of Congresswoman Suzan DelBene, DelBene, Schweikert Introduce Legislation to Modernize
ITC Process to Protect American Industry, Workers, and Consumers
(Aug. 14, 2020), at
274 Advancing America’s Interests Act, H.R. 8037, 116th Cong. (2020).
275 DelBene, Schweikert Introduce Legislation, supra note 273.
276 See generally Richards, supra note 8, at 32-41.
277 See discussion supra in “Inventorship Requirements.”
Congressional Research Service

Patent Law: A Handbook for Congress

Author Information

Kevin T. Richards

Legislative Attorney

This document was prepared by the Congressional Research Service (CRS). CRS serves as nonpartisan
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