Legal Sidebari

Barriers Along the U.S. Border: Key
Authorities and Recent Developments
October 23, 2023
On October 5, 2023, Secretary of Homeland Security Alejandro Mayorkas invoked Section 102(c) of the
Illegal Immigration Reform and Immigrant Responsibility Act of 1996 (IIRIRA), waiving requirements
under twenty-six federal statutes to expedite construction of twenty miles of barriers and related
infrastructure along the U.S.-Mexico border. Secretary Mayorkas said that the waiver did not signal a
“new Administration policy with respect to border walls.” From “day one,” the Secretary continued, that
policy had been that a “border wall is not the answer.”
Secretary Mayorkas’s waiver determination is the latest development in border barrier construction. The
Trump Administration identified more than $16 billion to construct barriers from amounts originally
available to the Departments of Defense (DOD), Treasury, and Homeland Security (DHS). It also issued
several Section 102(c) waivers to facilitate construction. The Biden Administration, by contrast, largely
ceased barrier construction, canceling certain construction contracts while generally suspending others.
Different Congresses have also placed more or less emphasis on barrier construction. Over the years,
Congress specified barrier miles that the Secretary of Homeland Security (the Secretary) had to construct,
and lawmakers have repeatedly modified the Secretary’s discretion over the location and characteristics of
those barriers. Congress has also varied how it makes appropriations for barrier construction, sometimes
expressly setting aside funds for fence or barrier system construction. This Sidebar examines the
Secretary’s October 2023 waiver in light of the statutes that authorize and fund barrier construction.
Authorization to Construct Barriers
Before 1996, federal immigration statute did not expressly authorize, much less expressly require,
construction of barriers to deter unlawful migration. Still, the federal government had erected barriers for
this purpose, apparently relying on the Attorney General’s general statutory responsibility to “guard the
boundaries and borders of the United States” against the illegal entry of aliens. (In 2003, Congress vested
this responsibility in the Secretary.) In 1996, Congress passed IIRIRA. Section 102 of the statute
(classified to the U.S. Code as a note to 8 U.S.C. § 1103) expressly instructs immigration authorities to
construct barriers along the international land borders to deter unauthorized migration. Congress last
amended Section 102 in 2007. The statute now expressly authorizes border barrier construction; imposes
Congressional Research Service
https://crsreports.congress.gov
LSB11059
CRS Legal Sidebar
Prepared for Members and
Committees of Congress

---

Congressional Research Service
2
minimum construction requirements; and permits the waiver of “all legal requirements” to expedite
construction.
Express Authority to Construct Border Barriers
Section 102(a) states that the Secretary “shall take such actions as may be necessary to install additional
physical barriers and roads . . . in the vicinity of the United States border to deter illegal crossings in areas
of high illegal entry into the United States.” The statute uses the term “shall,” which generally conveys a
statutory command. However, this statutory command is qualified by the language that follows it. Subject
to the minimum construction requirements of Section 102(b), the Secretary may determine the appropriate
amount of “additional” barriers to deploy. The Secretary may also determine the appropriate locations, in
the “vicinity of the United States Border,” to install barriers. The Secretary may construct barriers and
roads to “deter illegal crossings in areas of high illegal entry.” Section 102(b) also authorizes placement
of “lighting, cameras, and sensors to gain operational control of the southwest border.”
Minimum Construction Requirements
On its own, Section 102(a) generally permits the construction of “additional physical barriers and roads.”
Since IIRIRA’s enactment in 1996, though, Congress has qualified this general discretion in part by
imposing minimum mileage requirements.
The original statute required the Attorney General to construct fencing along a fourteen-mile section of
the border extending east from the Pacific Ocean near San Diego, California. In 2006, Congress expanded
the minimum mileage requirement to require barriers along five border segments in California, Arizona,
New Mexico, and Texas. According to DHS, meeting the 2006 requirement would have entailed building
about 854 miles of fencing because of the topography of the border segments specified in the statute.
Congress further revised the minimum mileage requirement to its current form in 2007. The Secretary
must “construct reinforced fencing along not less than 700 miles of the southwest border where fencing
would be most practical and effective and provide for the installation of additional physical barriers,
roads, lighting, cameras, and sensors to gain operational control of the southwest border.” While the
statute continues to mandate minimum barrier mileage, unlike the 1996 and 2006 enactments, it does not
require barriers in particular border segments. As of January 2021, the Trump Administration stated that
U.S. Customs and Border Protection (CBP) had approximately “701 miles of primary barriers.”
Congress has at times used Section 102(b) to qualify the Secretary’s discretion over the types of barriers
to install in an area where the statute required barriers to be constructed. (Appropriations acts can qualify
this discretion as well by, for example, limiting use of appropriations for only “operationally effective
designs” deployed as of a certain date or adaptations thereof.) The 1996 statute called for a second and
third layer of fencing along the San Diego-area segment. The 2006 enactment specified “at least 2 layers
of reinforced fencing” in each of the five border segments. IIRIRA now requires 700 miles of “reinforced
fencing,” rather than two or more layers of such fencing.
Waiver Authority
Since its original enactment, IIRIRA has vested immigration authorities with another form of discretion
intended to ensure “expeditious construction” of barriers and roads. Though an agency might have
statutory authority to undertake a construction project, use of that authority might be subject to planning
and other requirements under other federal statutes.
In 1996, Congress authorized the Attorney General to waive the provisions of the Endangered Species Act
of 1973 (ESA) and the National Environmental Policy Act of 1969 (NEPA) as needed to achieve

---

Congressional Research Service
3
expeditious barrier and road construction. In 2005, Congress expanded this waiver authority to its current
form. The Secretary now has “sole discretion” to waive “all legal requirements” as needed for expeditious
construction. The Secretary’s waivers are effective upon publication in the Federal Register. The
Secretary has invoked this waiver authority on more than thirty occasions. Only one such waiver—issued
in May 2020 for barrier and road projects in Webb County, Texas, and Zapata County, Texas—was later
rescinded in June 2023.
The 2005 revision to IIRIRA also restricted judicial review of the Secretary’s waivers. The federal district
courts have “exclusive jurisdiction” to hear “all causes or claims” arising from the Secretary’s waiver
authority. The statute further restricts the types of claims that may be brought. “A cause of action or claim
may only be brought alleging a violation of the Constitution of the United States. The court shall not have
jurisdiction to hear any [other] claim . . . .” IIRIRA limits appellate review of district court action.
Judgments and orders are not appealable to a federal circuit court as is normally the case in civil
litigation. Instead, they may be reviewed “only upon petition for a writ of certiorari to the Supreme Court
of the United States.”
The statute’s restrictions on judicial review concern “all causes or claims arising from” actions or
decisions made under the Secretary’s waiver authority. The U.S. Court of Appeals for the D.C. Circuit
(D.C. Circuit) has reasoned that the restriction does not extend, more broadly, to claims that do not
originate or stem from a waiver determination. Relatedly, the D.C. Circuit has asserted appellate
jurisdiction over waiver-related claims when a plaintiff brings an “ultra vires claim,” that is, a claim based
on an allegation that a waiver-related action is “obviously beyond the terms of the statute.” Plaintiffs have
not prevailed on ultra vires claims in this context.
Litigants have challenged Section 102(c) waivers on constitutional grounds. Some have attacked the
waiver authority as an impermissible delegation of Congress’s legislative power. Others challenged
waivers as executive authority to repeal or amend existing law in violation of the Bicameralism and
Presentment Clauses or as a derogation of the President’s Take Care Clause duty. Litigants have also cast
waivers as violations of the Tenth Amendment. All such challenges have failed.
Funding DHS Barrier Construction
IIRIRA authorizes barrier construction, but the statute does not provide budget authority for the costs of
construction. Budget authority is the authority to enter into obligations. Obligations are definite
commitments that create legal liabilities on the federal government’s part to make payments to third
parties. An expenditure, the payment of funds from the Treasury to a third party, is what satisfies an
obligation. An appropriation is the only form of budget authority that allows an agency to both incur
obligations and make expenditures from the Treasury to liquidate those obligations.
By the time President Biden assumed office in January 2021, the Trump Administration had identified
more than $16 billion in appropriations for barrier construction. These appropriations derived from three
sources. First, most of the funds came from DOD, which engaged in barrier construction as military
construction undertaken in connection with a national emergency or as support for counterdrug activities
following transfers from other appropriations (e.g., procurement and National Guard-related accounts).
Second, the Trump Administration tapped the Department of the Treasury Forfeiture Fund (TFF), a fund
credited with forfeiture receipts and available, in part, for the “law enforcement activities of any Federal
agency.” Third, the Trump Administration obligated appropriations available to CBP.
The Biden Administration determined that DOD appropriations and funds transferred to DHS from the
TFF should no longer be used for barrier construction. New obligations using these funds ceased, and the
government canceled existing contracts supported by the funds. The DOD and TFF funds used for these
contracts were not made expressly for barrier construction only, so unobligated balances remaining after

---

Congressional Research Service
4
the costs suspension and cancellation could be put to uses other than barrier construction. Thus, for
example, DOD dedicated “more than $2 billion” in military construction appropriations to sixty-six
previously deferred, non-barrier projects. Some DOD funds had expired and could not be used for new
obligations.
CBP appropriations are different: unlike the relevant DOD and TFF funds, Congress appropriated funds
to DHS in certain fiscal years expressly for barrier construction. CBP receives an annual appropriation
under the heading “Procurement, Construction, and Improvement” (PC&I) for the necessary expenses of
those CBP activities. Congress has constrained DHS’s allocation discretion over all or part of the CBP
PC&I appropriation through line-item appropriations included in statute, sometimes by expressly
referencing “fencing” or a “barrier system.” Congress made $1.375 billion of the FY2019 CBP PC&I
appropriation available “only” for “the construction of primary pedestrian fencing, including levee
pedestrian fencing, in the Rio Grande Valley Sector.” The same amount of funding, $1.375 billion, was
reserved “only” for “the construction of barrier system along the southwest border” in the FY2020 CBP
PC&I appropriation, a line item included in the FY2021 appropriation as well. Subsequent DHS
Appropriations Acts for FY2022 and FY2023 continue to make line-item appropriations for CBP PC&I
funds but do not refer to “fencing” or a “barrier system.”
The CBP PC&I appropriation is typically multiyear budget authority, available for the needs of not only
the fiscal year for which the appropriation is made but for two to four subsequent fiscal years as well.
After that period, the funds expire. Expired funds are not available for new obligations but are available
for five fiscal years after expiration for, among other things, making expenditures to liquidate obligations.
After that five-year period, the appropriation’s balances (obligated and unobligated) are canceled. CBP
uses five-year PC&I funds for border barrier construction.
The FY2019 Line Item and the October 2023 Waiver
In June 2021, DHS stated that it had not deobligated funds for CBP-funded contracts entered into during
the prior Administration. Limited, urgent work “to avert physical dangers” would continue under the
contracts in the meantime, using existing Section 102(c) waivers. Otherwise, DHS said that it would
suspend CBP-funded border barrier contracts while it engaged in planning and consultation activities. It
signaled that “rescinding or revising prior” Section 102(c) waivers “will not be feasible” for “some
segments.” Regardless of whether a waiver remained in effect, as of June 2021, DHS intended to engage
“in standard environmental planning” under NEPA and other statutes concerning use of FY2019 funds,
among others. In July 2022, DHS further explained that, for the remaining FY2019 funds, it intended to
prioritize “remediation and mitigation” from past barrier construction and the installation of “barrier
system attributes” (e.g., lighting) for fencing previously constructed using the FY2019 line item.
In June 2023, DHS authorized CBP to “move forward with the planning and execution of up to
approximately 20 miles of border barrier system” in the Rio Grande Valley Sector. DHS explained that it
would use FY2019 CBP PC&I appropriations for this purpose, of which there was $190 million
“remaining.” CBP “began to solicit public input on potential impacts” of this project in August 2023. The
comment period closed in September 2023. On September 28, two days before expiration of the FY2019
PC&I line item, CBP awarded a construction contract for the project. On October 5, Secretary Mayorkas
issued a Section 102(c) waiver for the twenty miles of barrier systems. That same day, Secretary
Mayorkas stated that the “construction project reported today was appropriated during the prior
administration in 2019 and the law requires the government to use these funds for this purpose.”
As noted above, $1.375 billion of the FY2019 CBP PC&I appropriation is available “only” for “the
construction of primary pedestrian fencing, including levee pedestrian fencing, in the Rio Grande Valley
Sector.” GAO has said that a line item of this form “presumptively ‘fences in’ the earmarked sum” by
setting both a “maximum and minimum” amount of budget authority that must be obligated for that

---

Congressional Research Service
5
purpose. Though CBP was thus required to obligate this amount, it had some discretion to decide the
particular expenses that would fit the object of fence construction. As future Supreme Court Justice Brett
Kavanaugh explained, an “appropriation made for a specific object is available for expenses necessarily
incident to accomplishing that object unless prohibited by law or otherwise provided for.” An agency has
discretion, in the first instance, to decide an “expenditure is reasonably necessary to accomplish the
agency’s mission.” Projects such as installing lighting for existing fencing previously constructed using
the FY2019 line item would seem to be incident to fence construction as much as the erection of new
fencing.
However, CBP could not decline to obligate the FY2019 PC&I fencing because it disagreed with the
object for which that appropriation had been made. Agencies cannot defer use of “budget authority for
general policy reasons.” Unless Congress rescinds budget authority, an agency must take steps to
“prudently” obligate an appropriation before it expires. The Biden Administration proposed rescission of
CBP PC&I funds, but Congress did not enact these proposals. Thus, CBP’s duty was to take steps to
prudently obligate the FY2019 CBP PC&I appropriation for fence construction before it expired.
The 2019 CBP funds obligated by September 30, 2023, remain available for expenditure through
September 30, 2028, to complete contract activities. Because of Secretary Mayorkas’s waiver,
“construction of roads and physical barriers” in the project area will not be affected by requirements
stemming from the twenty-six federal statutes identified in the waiver. While a litigant might try to
challenge the waiver, to date such challenges have not succeeded.


Author Information

Michael John Garcia
Sean M. Stiff
Deputy Assistant Director/ALD
Legislative Attorney





Disclaimer
This document was prepared by the Congressional Research Service (CRS). CRS serves as nonpartisan shared staff
to congressional committees and Members of Congress. It operates solely at the behest of and under the direction of
Congress. Information in a CRS Report should not be relied upon for purposes other than public understanding of
information that has been provided by CRS to Members of Congress in connection with CRS’s institutional role.
CRS Reports, as a work of the United States Government, are not subject to copyright protection in the United
States. Any CRS Report may be reproduced and distributed in its entirety without permission from CRS. However,
as a CRS Report may include copyrighted images or material from a third party, you may need to obtain the
permission of the copyright holder if you wish to copy or otherwise use copyrighted material.

LSB11059 · VERSION 1 · NEW

---