Class Action Lawsuits and Classwide Injunctive Relief
Congressional research reportJun 5, 2026
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Class Action Lawsuits and Classwide
Injunctive Relief
June 5, 2026
Congressional Research Service
https://crsreports.congress.gov
R48972
SUMMARY
Class Action Lawsuits and Classwide Injunctive
Relief
R48972
June 5, 2026
Bryan L. Adkins
Legislative Attorney
In Trump v. CASA, Inc., the Supreme Court limited the ability of federal courts to issue
nationwide (or universal) injunctions, which are court orders prohibiting the government from
implementing a challenged law, regulation, or other policy against all persons and entities,
including non-parties to the lawsuit. Trump v. CASA, Inc., 606 U.S. 831 (2025). Although CASA
limited the availability of nationwide injunctions, the decision left open a number of potential
avenues for litigants to obtain broad relief for persons or entities affected by allegedly unlawful government policies. Class
action lawsuits are one such avenue, and class actions have attracted increased attention as a potential alternative to
nationwide injunctions following CASA.
Whereas a nationwide injunction blocks the government from enforcing a law or policy against all persons and entities, a
class action is a form of representative action that seeks relief for members of a defined class. Classwide injunctive relief is
sometimes functionally equivalent to a nationwide injunction insofar as a class may be defined broadly to cover large
numbers of affected individuals or entities who are not participating actively in the case. Class actions in federal court must
satisfy certain procedural requirements.
Federal Rule of Civil Procedure 23 (Rule 23) governs class actions in federal courts. Rule 23’s requirements help ensure that
absent class members’ interests are protected and that the lawsuit is the type of case for which class treatment would be
beneficial. A lawsuit may not proceed on a class basis unless the court certifies the class upon determining that Rule 23’s
requirements are met. Smith v. Bayer Corp., 564 U.S. 299, 313–15 (2011). The party seeking class certification bears the
burden of demonstrating that the requirements are met, and the Supreme Court has held that courts must perform a “rigorous
analysis” before deciding whether certification is warranted. Wal-Mart Stores, Inc. v. Dukes, 564 U.S. 338, 350–52 (2011).
Class certification decisions often involve evidentiary hearings and may require the court to address complex legal issues that
overlap with the merits of the case.
To the extent class actions are viewed as an alternative to nationwide injunctions, some observers have expressed concern
that class certification may not always be possible to achieve quickly, or at all, in some cases in which courts otherwise may
have granted a nationwide injunction. See, e.g., Suzette M. Malveaux, Class Actions, Civil Rights, and the National
Injunction, 131 HARV. L. REV. F. 56, 58–60 (2017). In addition to the potential difficulty of satisfying Rule 23’s
requirements, obtaining class certification can also be expensive and time-consuming, and some courts and commentators
have raised questions about the extent to which courts may expedite class certification or grant injunctive relief for putative
class members without first certifying a class. See, e.g., L.G.M.L. v. Noem, 800 F. Supp. 3d 100, 117 n.3 (D.D.C. 2025). In
contrast, some legal scholars contend that obtaining certification for a class seeking injunctive relief against the government
is generally not as difficult as other commentators have suggested. See, e.g., David Marcus, The Class Action After Trump v.
CASA, 72 UCLA L. REV. DISCOURSE 2, 8–9. The prospect of using class actions as a substitute for nationwide injunctions has
also raised concerns that district courts may become too permissive in certifying class actions after CASA, and that loose
enforcement of Rule 23’s certification requirements could undermine the CASA ruling.
Plaintiffs have obtained broad, classwide injunctions in a number of class actions challenging government policies since the
Supreme Court’s CASA decision, but it remains to be seen how the Supreme Court may respond as more such cases work
through the judicial system. The extent to which class actions may become a substitute for nationwide injunctions after CASA
remains subject to ongoing debate.
Nationwide injunctions have received substantial attention from the 119th Congress, and some legal scholars have observed
that nationwide class actions against the government may implicate similar policy concerns as nationwide injunctions in
certain respects. See, e.g., Michael T. Morley, Disaggregating Nationwide Injunctions, 71 ALA. L. REV. 1, 52–53 (2019);
David Marcus, The Class Action After Trump v. CASA, 72 UCLA L. REV. DISCOURSE at 23. Congress has substantial
constitutional authority to regulate federal court procedures, including the procedures that apply to class action lawsuits.
Hanna v. Plumer, 380 U.S. 460, 472 (1965). In light of the increased focus on class actions as a potential substitute for
nationwide injunctions, Congress may choose to monitor the use of the class action device in lawsuits seeking injunctive
relief against the government, and evaluate whether such use aligns with Congress’s preferences. If Congress wished, it could
consider legislating to expand or limit the ability of plaintiffs to bring suits challenging government policies on a class action
basis.
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Class Action Lawsuits and Classwide Injunctive Relief
Contents
Background on Class Actions.......................................................................................................... 2
Class Certification Under Rule 23 ................................................................................................... 4
Rule 23(a) .................................................................................................................................. 4
Rule 23(b) ................................................................................................................................. 6
Classwide Injunctions...................................................................................................................... 6
Preliminary Injunctive Relief in Class Actions ............................................................................... 9
Class Actions as an Alternative to Nationwide Injunctions ............................................................ 11
Considerations for Congress.......................................................................................................... 13
Contacts
Author Information........................................................................................................................ 15
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I
n Trump v. CASA, Inc.,1 the Supreme Court limited the ability of federal courts to issue
nationwide (or universal) injunctions, which are court orders prohibiting the government from
implementing a challenged law, regulation, or other policy against all relevant persons and
entities, including non-parties to the lawsuit.2 An injunction is a “court order commanding or
preventing an action,”3 and the Supreme Court has explained that the difference between a
traditional injunction and a nationwide injunction is “not so much where it applies, but whom it
protects.”4 While “[e]ven a traditional, parties-only injunction can apply beyond the jurisdiction
of the issuing court,” a nationwide injunction “prohibits the Government from enforcing [a] law
against anyone, anywhere.”5
Although CASA limited the availability of nationwide injunctions, the decision left open a number
of potential avenues for litigants to obtain broad relief from a court to block enforcement of
allegedly unlawful government policies against large numbers of affected persons or entities.6
Class action lawsuits are one such legal mechanism, and class actions have attracted increased
attention as a potential alternative to nationwide injunctions.7
Whereas a nationwide injunction blocks the government from enforcing a law or policy against
all persons and entities, a class action is a form of representative action that seeks relief for
members of a defined class who have all suffered the same injury.8 The Supreme Court’s majority
opinion in CASA characterized nationwide injunctions as a “class-action workaround.”9 In the
majority’s view, by providing a “shortcut to relief that benefits parties and nonparties alike,
1 Trump v. CASA, Inc., 606 U.S. 831 (2025).
2 Although nationwide injunction appears to be the most common term for an injunction that blocks government action
against anyone, courts and legal commentators also refer to these injunctions by other names, such as universal
injunctions, which is the Supreme Court’s preferred term. See, e.g., CASA, 606 U.S. at 838 n.1 (observing that “the
term ‘universal’ better captures how these injunctions work”).
For an in-depth discussion of nationwide injunctions and the CASA decision, see CRS Report R46902, Nationwide
Injunctions: Law, History, and Proposals for Reform, by Joanna R. Lampe (2021); and CRS Report R48600, Trump v.
CASA, Inc. and Nationwide Injunctions During the Second Trump Administration, by Joanna R. Lampe (2025).
3 Injunction, BLACK’S LAW DICTIONARY (12th ed. 2024).
4 CASA, 606 U.S. at 838 n.1.
5 Id.
6 For example, courts hearing challenges to government actions under the Administrative Procedure Act, ch. 324, 60
Stat. 237 (1946), sometimes universally stay a challenged action while a case is pending or vacate the agency action
following litigation on the merits, which can have a universal effect. See Harmon v. Thornburgh, 878 F.2d 484, 495
n.21 (D.C. Cir. 1989) (“When a reviewing court determines that agency regulations are unlawful, the ordinary result is
that the rules are vacated—not that their application to the individual petitioners is proscribed.”). In CASA, 606 U.S. at
847 n.10, the Supreme Court expressly declined to resolve “the distinct question whether the Administrative Procedure
Act authorizes federal courts to vacate federal agency action.”
For additional background on vacatur under the Administrative Procedure Act, see CRS Legal Sidebar LSB11357, “Set
Aside” and Vacatur Under the Administrative Procedure Act, by Benjamin M. Barczewski (2025). For discussion of
other potential avenues for obtaining universal judicial relief after CASA, see CRS Legal Sidebar LSB11331, Trump v.
CASA, Inc.: Supreme Court Limits Nationwide Injunctions, by Joanna R. Lampe (2025).
7 See, e.g., David Lat, Class Actions Might Be The Surprise Fix For Problems With Universal Injunctions, ORIGINAL
JURISDICTION (May 21, 2025), https://davidlat.substack.com/p/class-actions-might-partially-fix-universal-ornationwide-injunctions-birthright-citizenship-arguments-casa-aarp-v-trump [https://perma.cc/A7YH-6EHK]; Brian
Fitzpatrick, The Perils of Using Class Actions as a Replacement for Universal Injunctions, SCOTUSBLOG (Aug. 12,
2025), https://www.scotusblog.com/2025/08/the-perils-of-using-class-actions-as-a-replacement-for-universalinjunctions/ [https://perma.cc/E6N8-6XJP].
8 See Wal-Mart Stores, Inc. v. Dukes, 564 U.S. 338, 348–49 (2011).
9 CASA, 606 U.S. at 850 (citing CASA, 606 U.S. at 900–03 (Sotomayor, J., dissenting)).
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[nationwide] injunctions circumvent Rule 23’s procedural protections and allow ‘courts to create
de facto class actions at will.’”10
Classwide injunctive relief is sometimes functionally equivalent to a nationwide injunction11
insofar as it may block the government from implementing a challenged policy with respect to a
broad group of persons or entities who are not participating actively in the case.12 For a lawsuit to
proceed as a class action in federal court, however, the lawsuit must satisfy the requirements of
Federal Rule of Civil Procedure 23 (Rule 23).13 While plaintiffs have obtained certification of
broad, nationwide classes since the CASA decision in some cases in which the courts had
previously issued a nationwide injunction,14 obtaining class certification under Rule 23 can be
difficult and time-consuming. The extent to which class actions will become a substitute for
nationwide injunctions following the CASA decision remains subject to ongoing debate.15
Additionally, nationwide injunctions have received substantial attention from the 119th
Congress,16 and some legal scholars have observed that nationwide class actions against the
government may implicate similar policy concerns as nationwide injunctions in certain respects.17
This report provides an overview of the class action mechanism and Rule 23’s certification
requirements, examines legal questions concerning the availability of classwide injunctive relief,
and discusses ongoing debates over the extent to which class actions are a substitute for
nationwide injunctions. This report concludes with considerations for Congress.
Background on Class Actions
A class action lawsuit is a form of representative action that aggregates the legal claims of
numerous individuals or entities into a single proceeding. The general rule in American litigation
is that lawsuits are brought on behalf of the named parties, but the class action mechanism is an
exception that permits one or more named plaintiffs to sue a defendant on their own behalf and as
representatives of a larger group of persons who have allegedly suffered the same injury.18
Whereas plaintiffs in ordinary multi-plaintiff lawsuits each participate in the litigation, in class
actions the unnamed class members—also called absent class members—typically do not actively
participate in the litigation and may not even be aware of their potential claims when the lawsuit
is filed.19 Although the unnamed members of a class are not formal “parties” to the litigation in
10 Id. (quoting Smith v. Bayer Corp., 564 U.S. 299, 315 (2011)).
11 See CASA, 606 U.S. at 873 (Kavanaugh, J. concurring) (describing “a preliminary injunction to a putative nationwide
class under Rule 23(b)(2)” as “the functional equivalent of a universal injunction”).
12 Califano v. Yamasaki, 442 U.S. 682 (1979).
13 FED. R. CIV. P. 23; Smith v. Bayer Corp., 564 U.S. 299, 315 (2011).
14 See CASA, Inc. v. Trump, 793 F. Supp. 3d 703, 728–29 (D. Md. 2025); Pacito v. Trump, 796 F. Supp. 3d 692 (W.D.
Wash. 2025).
15 See, e.g., Suzette M. Malveaux, Class Actions, Civil Rights, and the National Injunction, 131 HARV. L. REV. F. 56, 58
(2017); Amanda Frost, In Defense of Nationwide Injunctions, 93 N.Y.U. L. REV. 1065, 1095–97 (2018); David Marcus,
The Class Action After Trump v. CASA, 72 UCLA L. REV. DISCOURSE 2, 23 (2025); Fitzpatrick, supra note 7.
16 See infra note 116.
17 See infra note 117.
18 Gen. Tel. Co. of Sw. v. Falcon, 457 U.S. 147, 155 (1982). While plaintiff classes are most common, federal courts
also may certify classes of defendants. Defendant class actions are rare and raise different considerations than plaintiff
class actions. See Bell v. Brockett, 922 F.3d 502, 504 (4th Cir. 2019). The discussion in this report is limited to plaintiff
class actions.
19 Phillips Petroleum Co. v. Shutts, 472 U.S. 797, 810 (1985) (“[A]n absent class-action plaintiff is not required to do
(continued...)
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the sense of participating in and directing the litigation,20 they “are considered parties to the
litigation in many important respects,”21 and are generally bound by a final judgment resolving
their legal claims in the case.22
The Supreme Court has observed that a primary purpose of class actions is to improve the
“efficiency and economy of litigation.”23 When many persons have allegedly suffered the same
injury from a defendant’s conduct, aggregating the claims into a single class action lawsuit may
allow courts and parties to avoid the time and expense of litigating large numbers of duplicative
individual lawsuits.24 Also, by enabling class representatives to litigate numerous other parties’
claims in a single proceeding, class actions can serve to vindicate rights and deter wrongdoing,
such as where injured class members may lack the means to hire their own attorneys, or the costs
of litigating may not justify bringing a claim on an individual basis.25
Courts have also recognized that class actions may be subject to abuse. For instance, because
unnamed class members generally are not directly involved in the litigation, class actions can
create a risk that the class representatives or class attorneys might place their own interests ahead
of those of absent class members in litigating the case.26 Additionally, aggregating numerous
claims into a single proceeding can create intense pressure on a defendant to settle even
unmeritorious legal claims.27
While the class action mechanism has roots in early English law, the modern class action in the
United States was created in Rule 23,28 which governs class actions in federal courts.29 The
anything . . . [and] may sit back and allow the litigation to run its course, content in knowing that there are safeguards
provided for his protection.”).
20
See, e.g., Williams v. Gen. Elec. Cap. Auto Lease, Inc., 159 F.3d 266, 269 (7th Cir. 1998).
21 United States v. Sanchez-Gomez, 584 U.S. 381, 387 (2018). See also, e.g., Devlin v. Scardelletti, 536 U.S. 1, 9–10
(2002) (explaining that unnamed class members “may be parties for some purposes and not for others,” and that “[t]he
label ‘party’ does not indicate an absolute characteristic, but rather a conclusion about the applicability of various
procedural rules that may differ based on context”).
22 Cooper v. Fed. Rsrv. Bank of Richmond, 467 U.S. 867, 874 (1984) (“There is of course no dispute that under
elementary principles of prior adjudication a judgment in a properly entertained class action is binding on class
members in any subsequent litigation.”); Hansberry v. Lee, 311 U.S. 32, 41 (1940).
23 Am. Pipe & Const. Co. v. Utah, 414 U.S. 538, 553 (1974); Crown, Cork & Seal Co. v. Parker, 462 U.S. 345, 349
(1983).
24 Falcon, 457 U.S. at 155.
25 Amchem Prods., Inc. v. Windsor, 521 U.S. 591, 617 (1997).
26 See, e.g., Eubank v. Pella Corp., 753 F.3d 718, 720 (7th Cir. 2014).
27 See, e.g., Messner v. Northshore Univ. HealthSystem, 669 F.3d 802, 825 (7th Cir. 2012).
28 Ortiz v. Fibreboard Corp., 527 U.S. 815, 832–33 (1999). For further background on the origins and development of
the modern class action, see STEPHEN YEAZELL, FROM MEDIEVAL GROUP LITIGATION TO THE MODERN CLASS ACTION
(1987); Benjamin Kaplan, Continuing Work of the Civil Committee: 1966 Amendments of the Federal Rules of Civil
Procedure (i), 81 HARV. L. REV. 356 (1967).
29 More specifically, Rule 23 governs class actions in federal district courts, which are the primary trial courts in the
federal court system. See FED. R. CIV. P. 1 (specifying that, with certain exceptions, the Federal Rules of Civil
Procedure “govern the procedure in all civil actions and proceedings in the United States district courts”); About U.S.
District Courts, U.S. CTS., https://www.uscourts.gov/about-federal-courts/court-role-and-structure/about-us-districtcourts [https://perma.cc/2TGP-GZ44] (last visited Mar. 30, 2026) (providing an overview of the role and structure of
federal district courts). Two specialized federal trial courts—the U.S. Court of Federal Claims and the U.S. Court of
International Trade—have their own class action rules modeled on Federal Rule of Civil Procedure 23. See CT. INT’L
TRADE R. 23; FED. CL. R. 23.
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Supreme Court first promulgated Rule 23 in 1937,30 and major amendments in 1966 remade the
rule into its modern form.31
Class Certification Under Rule 23
For a lawsuit to proceed as a class action under Rule 23, the plaintiff or plaintiffs seeking to
represent the class must establish that the lawsuit satisfies certain requirements enumerated in
Rule 23(a) and (b),32 discussed below. These requirements help ensure that absent class members’
interests are protected and that the lawsuit is the type of case for which class treatment would be
beneficial.33 The lawsuit may not proceed on a class basis unless the court certifies the class upon
determining that the requirements are met.34 The party seeking class certification bears the burden
of “affirmatively demonstrating” that the requirements are met, and courts must perform a
“rigorous analysis” before deciding whether certification is warranted.35 Class certification
decisions often involve evidentiary hearings36 and may require the court to address complex legal
issues that overlap with the merits of the case.37
A lawsuit that seeks to bring claims on behalf of a class that has not yet been certified is
commonly referred to as a putative class action, and members of the uncertified class are putative
class members.38 If a court concludes that a putative class satisfies Rule 23’s certification
requirements, then it issues a certification order defining the class and appointing class counsel.39
Rule 23(a)
A class action must meet all four of the prerequisites listed in Rule 23(a), which are commonly
known as numerosity, commonality, typicality, and adequacy of representation.40
•
Numerosity. Under Rule 23(a)(1), the proposed class must be so large that it
would be “impracticable” for all the class members to be joined to the
proceeding.41 There is not a strict numerical cutoff, but as a rule of thumb, courts
30 As discussed below, the Rules Enabling Act (P.L. 100-702, tit. IV, 102 Stat. 4648 (1988) (codified as amended at 28
U.S.C. §§ 2071–2077)) authorizes the Supreme Court to create and amend federal procedural rules, such as Rule 23.
31 Amchem Prods., Inc. v. Windsor, 521 U.S. 591, 613 (1997) (“Rule 23, governing federal-court class actions, stems
from equity practice and gained its current shape in an innovative 1966 revision.”).
32 Id. at 613–14.
33 Wal-Mart Stores, Inc. v. Dukes, 564 U.S. 338, 350 (2011).
34 FED. R. CIV. P. 23(c)(1); Genesis Healthcare Corp. v. Symczyk, 569 U.S. 66, 75 (2013) (“[A] putative class acquires
an independent legal status once it is certified under Rule 23.”); Standard Fire Ins. Co. v. Knowles, 568 U.S. 588, 593
(2013) (“[A] plaintiff who files a proposed class action cannot legally bind members of the proposed class before the
class is certified.”); Smith v. Bayer Corp., 564 U.S. 299, 313–14 (2011) (“Neither a proposed class action nor a rejected
class action may bind nonparties. What does have this effect is a class action approved under Rule 23.”).
35 Wal-Mart, 564 U.S. at 350–52.
36 See ANN. MANUAL COMPLEX LIT. § 21.21 (4th ed.).
37 Wal-Mart, 564 U.S. at 351–52.
38 See, e.g., China Agritech v. Resh, 584 U.S. 732 (2018) (discussing putative class actions and putative class
members).
39 FED. R. CIV. P. 23(c)(1).
40 Amchem Prods., Inc. v. Windsor, 521 U.S. 591, 613 (1997).
41 FED. R. CIV. P. 23(a)(1).
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•
•
•
have observed that classes with more than forty members generally satisfy the
numerosity requirement.42
Commonality. Under Rule 23(a)(2), there must be “questions of law or fact
common to the class.”43 Although the Supreme Court has held that even one
“common question” is enough to satisfy this requirement,44 the Court has
interpreted the common-question requirement as more demanding than what a
literal reading of the rule might suggest.45
In Wal-Mart Stores, Inc. v. Dukes, the Supreme Court explained that it is not
enough that the class members’ claims “literally raise[] common questions,” but
instead the common question must be capable of generating a “common answer”
that would resolve an issue central to the class members’ claims in “one stroke.”46
Commonality thus requires that the class members have “suffered the same
injury,” and not “merely that they have all suffered a violation of the same
provision of law.”47
Typicality. Under Rule 23(a)(3), the “claims or defenses of the representative
parties” must be “typical of the claims or defenses of the class.”48 This essentially
requires there to be sufficient similarity between the legal and factual bases of the
representative plaintiffs’ claims and the class members claims.49 The Supreme
Court has explained that the commonality and the typicality requirements “tend
to merge” and that “[b]oth serve as guideposts” for determining whether a class
action would be economical and whether the claims of the class representatives
and absent class members are so interrelated that the interests of the absent class
members will be adequately protected.50
Adequacy of Representation. Rule 23(a)(4) requires that class representatives
will “fairly and adequately protect the interests of the class.”51 The adequacy
requirement considers potential conflicts of interest between class representatives
42 See, e.g., In re Nat’l Football League Players Concussion Inj. Litig., 821 F.3d 410, 426 (3d Cir. 2016), as amended
(May 2, 2016).
43 FED. R. CIV. P. 23(a)(2).
44 Wal-Mart Stores, Inc. v. Dukes, 564 U.S. 338, 359 (2011).
45 Id.
46 Id. at 350.
47 Id. In the lower court proceedings in Wal-Mart, a federal district court had certified a class of all female employees at
Wal-Mart stores nationwide in a Title VII sex discrimination lawsuit, and on appeal the Supreme Court ruled that the
class did not satisfy Rule 23(a)’s commonality requirement. Id. at 358. The Court reasoned that the Title VII
discrimination claims depended on the reasons for particular employment decisions, but Wal-Mart gave its local
managers significant discretion in making employment decisions, and plaintiffs had not established that the store
managers across the nation exercised their discretion in a common way. Id. In the Court’s view, because they failed to
establish that the employees were subject to a uniform employment policy or practice across the stores nationwide, the
plaintiffs were unable to show that all the employees’ Title VII claims depended on the answers to common questions.
Id.
48 FED. R. CIV. P. 23(a)(3).
49 See, e.g., Small v. Allianz Life Ins. Co. of N. Am., 122 F.4th 1182, 1201–02 (9th Cir. 2024); Angell v. GEICO
Advantage Ins. Co., 67 F.4th 727, 736 (5th Cir. 2023); In re Schering Plough Corp. ERISA Litig., 589 F.3d 585, 597
(3d Cir. 2009).
50 Wal-Mart, 564 U.S. at 350 n.5 (2011) (quoting Gen. Tel. Co. of Sw. v. Falcon, 457 U.S. 147, 157–158, n.13 (1982).
The Supreme Court has observed that the commonality and the typicality requirements therefore also tend to merge
with the adequacy of representation requirement. Id.
51 FED. R. CIV. P. 23(a)(4).
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or class counsel and absent class members, and whether the class counsel and
class representatives will competently litigate the claims on behalf of the class.52
Rule 23(b)
In addition to satisfying all four of the Rule 23(a) prerequisites, a class must also fall into one of
the types of class actions permitted under Rule 23(b). While Rule 23(b) permits multiple types of
class actions,53 this report focuses on class actions brought under Rule 23(b)(2), which permits
class actions seeking injunctive relief. Rule 23(b)(2) specifically authorizes class actions where
“the party opposing the class has acted or refused to act on grounds that apply generally to the
class, so that final injunctive relief or corresponding declaratory relief is appropriate respecting
the class as a whole.”54
The Supreme Court has explained that Rule 23(b)(2) permits class actions when a single
injunction would provide relief to all the class members, but not when the lawsuit primarily seeks
individualized relief for class members.55 Rule 23(b)(2) therefore does not authorize a class
“when each individual class member would be entitled to a different injunction . . . against the
defendant.”56 A “prime example[]” of a class action under Rule 23(b)(2) is a civil rights lawsuit
seeking a court order to stop a defendant from engaging in class-based discrimination.57
In contrast to class actions seeking money damages, in which class members have the right to
notice of class certification and may choose to opt out of the class,58 injunctive relief classes
under Rule 23(b)(2) are considered “mandatory” classes in that class members do not have the
right to notice of class certification or to exclude themselves from the class.59
Classwide Injunctions
Whereas a nationwide injunction blocks the government from enforcing a law or policy against
all persons and entities, a class action seeks relief for members of a defined class. A class may be
defined broadly and may include class members located across the country,60 and courts have
ordered broad, classwide injunctive relief against the federal government in class action lawsuits
both before and after the CASA decision.61
In 1979, for example, the Supreme Court upheld a district court’s decision to certify a nationwide
class under Rule 23(b)(2) in Califano v. Yamasaki, a lawsuit challenging the legality of certain
procedures a federal agency had implemented for recouping the overpayment of social security
52 Amchem Prods., Inc. v. Windsor, 521 U.S. 591, 625–26, 26 n.20 (1997).
53 Class actions seeking money damages are the most common type of class action and are generally brought under a
different category, Rule 23(b)(3), which imposes additional requirements. Rule 23(b)(1) permits class actions in certain
circumstances where it would be “impossible or unworkable” to litigate a claim individually, Wal-Mart, 564 U.S. at
361, and is a less common type of class action.
54 FED. R. CIV. P. 23(b)(2).
55 Wal-Mart, 564 U.S. at 338.
56 Id. at 360–61.
57 Id. at 361.
58 FED. R. CIV. P. 23(c)(2).
59 Wal-Mart, 564 U.S. at 361–62.
60 Califano v. Yamasaki, 442 U.S. 682 (1979).
61 See, e.g., Califano, 442 U.S. 682; Barbara v. Trump, 790 F. Supp. 3d 80, 90 (D.N.H. 2025), cert. granted before
judgment sub nom., Trump v. Barbara, 146 S. Ct. 879 (2025).
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benefits.62 The district court had certified a class that included, subject to limited exceptions,63 all
individuals nationwide who were eligible for old age and survivor Social Security benefits and
whose benefits were being subjected to the recoupment procedures.64
The Supreme Court explained that “[n]othing in Rule 23 . . . limits the geographical scope of a
class action that is brought in conformity with that Rule.”65 The Court also reasoned that
awarding injunctive relief to the nationwide class was consistent with equity jurisprudence
principles because “the scope of injunctive relief is dictated by the extent of the violation
established, not by the geographical extent of the plaintiff class.”66
While the Califano Court concluded that “certifying a nationwide class is committed in the first
instance to the discretion of the district court,”67 the Court also cautioned that nationwide classes
may have “detrimental effects” in some cases.68 For example, granting injunctive relief to a
nationwide class may foreclose consideration of the issues by multiple different courts.69
According to the Court, “[i]t often will be preferable to allow several courts to pass on a given
class claim in order to gain the benefit of adjudication by different courts in different factual
contexts.”70 The Court also observed that nationwide class actions can sometimes increase
pressure on the Court’s docket.71 Accordingly, the Court emphasized that district courts
considering whether to certify a nationwide class should “take care to ensure that nationwide
relief is indeed appropriate in the case before it, and that certification of such a class would not
improperly interfere with the litigation of similar issues in other judicial districts.”72
Since the Court’s 2025 CASA decision, plaintiffs have obtained certification of broad, nationwide
classes in some cases in which district courts had previously granted nationwide injunctions,
62 Califano, 442 U.S. 682.
In certifying the class, the district court “excluded from the class residents of Hawaii and the Eastern District of
Pennsylvania, where suits raising similar issues were known to have been brought.” Id. at 679. The district court also
“excluded all persons who had participated as plaintiffs or members of a plaintiff class in litigation against the
Secretary on similar issues, if a decision on the merits previously had been rendered.” Id.
64 Id. at 689.
65 Id. at 702. The Supreme Court held that the district court “did not abuse its discretion in certifying a nationwide
class,” but also held that the class definition was overbroad in a different respect. Id. The Court explained that the
jurisdictional statute under which the plaintiffs had sued provided for judicial review of a “final decision of the
Secretary” and that “no ‘final decision” concerning the right to a prerecoupment hearing” would be made for persons
who did not file a request for reconsideration or waiver. Id. at 704. The Court therefore held that the class definition
should have excluded “persons who had not filed requests for reconsideration or waiver in the past and would not do so
in the future.” Id.
66 Id.
67 Id. at 703.
68 Id. at 702.
69
Id.
70 Id.
71 Id.
72 Id. Legal scholars debate under what circumstances it is appropriate for courts to certify nationwide classes in cases
against the government. See, e.g., Michael T. Morley, Nationwide Injunctions, Rule 23(b)(2), and the Remedial Powers
of the Lower Courts, 97 B.U. L. REV. 615, 625 (2017) (arguing that “[c]ourts should presumptively avoid certifying
nationwide classes under Rule 23(b)(2) when plaintiffs challenge the constitutionality or proper interpretation of a
federal legal provision,” and that such nationwide classes are “inconsistent with the structure of the federal judicial
system”); Marcus, supra note 15, at 31–32 (arguing that “[d]istrict courts should balance a host of factors . . . as they
consider a class’s geographic scope” and that “there is no doctrinal basis” for the argument that nationwide class
actions challenging federal policy are inconsistent with the structure of the federal judicial system).
63
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including in the CASA case itself.73 For example, the Supreme Court’s CASA ruling addressed
nationwide injunctions74 that had blocked enforcement of Executive Order No. 14160, Protecting
the Meaning and Value of American Citizenship (the Birthright Citizenship E.O.).75 The Court
held that those nationwide injunctions were invalid to the extent they went beyond what was
necessary to provide complete relief to the plaintiffs.76 Some of the plaintiffs in the underlying
CASA litigation subsequently sought certification of a class composed of all children nationwide
who are subject to the Birthright Citizenship E.O., and the parents of such children.77 The
plaintiffs also asked the district court to issue a classwide preliminary injunction enjoining
enforcement of the E.O. against the class members.
The district court certified a Rule 23(b)(2) injunctive-relief class and defined the class as all
children nationwide whose parents met the criteria listed in the Birthright Citizenship E.O. for
withholding citizenship.78 The court also granted a classwide preliminary injunction prohibiting
the government from enforcing the Birthright Citizenship E.O. against the class members. The
district court did not include parents of the children in the class, because it determined that the
parents’ claims did not satisfy Rule 23(a)’s commonality requirement.79 According to the court,
while the children’s claims satisfied commonality due to the nature of the common injury they
faced in the form of being denied U.S. citizenship under the Birthright Citizenship E.O., the
parents’ claims would vary depending on their individual circumstances, such as whether they
were seeking government benefits for their children based on their children’s citizenship.80
73 See CASA, Inc. v. Trump, 793 F. Supp. 3d 703 (D. Md. 2025); Pacito v. Trump, 796 F. Supp. 3d 692 (W.D. Wash.
2025).
74 Trump v. CASA was a consolidated appeal addressing three cases in which district courts had issued injunctions
blocking enforcement of the Birthright Citizenship E.O. See Trump v. CASA, Inc., 606 U.S. 831, 838 (discussing the
procedural background).
75 Exec. Order No. 14160, 90 Fed. Reg. 8449 (2025). Section 2 of the Birthright Citizenship E.O. declares that “it is the
policy of the United States that no department or agency of the United States government shall issue documents
recognizing United States citizenship, or accept documents issued by State, local, or other governments or authorities
purporting to recognize United States citizenship,” of persons born in the United States to specified categories of alien
parents thirty days or more after the date of the E.O. Id.
For further background on the Birthright Citizenship E.O. and related litigation, see CRS Legal Sidebar LSB11414,
Birthright Citizenship: Litigation Status Update, by Hannah Solomon-Strauss and Juria L. Jones (2026); CRS Legal
Sidebar LSB11331, Trump v. CASA, Inc.: Supreme Court Limits Nationwide Injunctions, by Joanna R. Lampe (2025).
76 CASA, 606 U.S. at 861.
77 CASA, Inc. v. Trump, 793 F. Supp. 3d 703 (D. Md. 2025).
78 Id.
79 Id. at 728–29.
80
Id. at 720–21. The district court’s classwide injunction in CASA remains in place as of the date of this report. The
government appealed the district court’s classwide preliminary injunction order (but not the class certification order) to
the U.S. Court of Appeals for the Fourth Circuit (Fourth Circuit), see Government’s Notice to Appeal, CASA, Inc. v.
Trump, 793 F. Supp. 3d 703 (D. Md. 2025) (No. 8:25-CV-00201), Dkt. No. 141, and the district court stayed its
proceedings pending the Fourth Circuit’s disposition of the appeal, see Order Granting Motion to Stay, CASA, Inc. v.
Trump, 793 F. Supp. 3d 703 (D. Md. 2025) (No. 8:25-CV-00201), Dkt. No. 146. The government subsequently sought
Supreme Court review in two separate cases involving challenges to the Birthright Citizenship E.O. See Barbara v.
Trump, No. 25-1861 (1st Cir. Sept. 29, 2025), cert granted before judgment sub nom., Trump v. Barbara, 146 S. Ct.
879 (2025), and Washington v. Trump, No. 25-807 (9th Cir. July 23, 2025), petition for cert. filed sub nom., Trump v.
Washington, No. 25-364 (U.S. Sept. 26, 2025). The Fourth Circuit in turn placed the appeal in CASA in abeyance
pending the Supreme Court’s disposition of those cases, see Order Granting Motion for Abeyance, CASA, Inc. v.
Trump, No. 25-2188 (4th Cir. Dec. 9, 2025).
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Preliminary Injunctive Relief in Class Actions
A court may issue a permanent injunction after it has decided a case on the merits. Plaintiffs also
may seek injunctive relief earlier in the case in the form of a temporary restraining order (TRO)81
or preliminary injunction82 to protect against an immediate threat of irreparable harm and
preserve the status quo. Questions over the extent to which courts may grant injunctive relief in
the early stages of a class action have generated significant debate following the CASA decision.
As discussed above, before a court grants class certification, it must conduct a “rigorous analysis”
to ensure the class satisfies Rule 23.83 This process can be time-consuming and potentially may
require the court to resolve evidentiary disputes and complex legal questions. When faced with
requests for a TRO or preliminary injunction in the class action context, courts sometimes decide
class certification on an expedited basis—in some cases on the same day the lawsuit is filed84—
and then “provisionally” certify the class for purposes of issuing the TRO or preliminary
injunctive relief to the class members.85
Although characterizing class certification as “provisional” may imply that a court has not
conducted a full Rule 23 analysis, some courts that have provisionally certified a class for
purposes of issuing a preliminary injunction have asserted that they applied the same “rigorous
analysis” of the Rule 23 requirements as in other class certification contexts.86 A class action
treatise explains that courts characterizing class certification as “provisional” generally do not
81 A TRO is a “court order preserving the status quo until a litigant’s application for a preliminary or permanent
injunction can be heard,” and TROs “may sometimes be granted without notifying the opposing party in advance.”
Temporary Restraining Order, BLACK’S LAW DICTIONARY (12th ed. 2024).
82 A preliminary injunction is a “temporary injunction issued before or during trial to prevent an irreparable injury from
occurring before the court has a chance to decide the case,” and is issued “only after the defendant receives notice and
an opportunity to be heard.” Injunction, BLACK’S LAW DICTIONARY (12th ed. 2024).
83 See supra “Class Certification Under Rule 23.”
84 In J.G.G. v. Trump, a group of Venezuelan nationals filed a putative class action lawsuit in the U.S. District Court for
the District of Columbia seeking to enjoin the Trump Administration from deporting them and a class of other
Venezuelan nationals under the Alien Enemies Act (ch. 58, 1 Stat. 570 (1798)). See Complaint, J.G.G. v. Trump, No.
25-CV-00766 (D.D.C. Mar. 15, 2025). The same day that the plaintiffs filed the lawsuit, the district court held a class
certification hearing and provisionally certified a class defined as “All noncitizens in U.S. custody who are subject to
the March 15, 2025, Presidential Proclamation entitled ‘Invocation of the Alien Enemies Act Regarding the Invasion of
The United States by Tren De Aragua’ and its implementation.” See Order Granting Motion to Certify, J.G.G. v.
Trump, No. 25-CV-00766, (D.D.C. Mar. 15, 2025). The Court also granted a TRO prohibiting the government from
deporting members of the class for fourteen days. Id.
The Supreme Court subsequently overturned the restraining order on the basis that the specific legal claims the
plaintiffs had asserted could only be brought in the judicial district in which the plaintiffs were being detained, and that
the federal district court in Washington, DC, therefore lacked jurisdiction over the claims. Trump v. J.G.G., 604 U.S.
670 (2025). For more information on this litigation, see CRS Legal Sidebar LSB11295, J.G.G. v. Trump: Supreme
Court’s Initial Review of Actions Taken Under the Alien Enemy Act, by Jennifer K. Elsea (2025).
85 See, e.g., CASA, Inc. v. Trump, 793 F. Supp. 3d 703, 728–29 (D. Md. 2025).
86 E.g., Barbara v. Trump, 790 F. Supp. 3d 80, 90 (D.N.H. 2025) (granting provisional class certification and explaining
that “‘[p]rovisional’ certification does not lower the bar with respect to the Rule 23(a) and (b) standards; the court must
conduct a rigorous inquiry and satisfy itself that the putative class meets those requirements”) (quoting Gomes v.
Acting Sec., U.S. Dep’t of Homeland Sec., No. 20-CV-453-LM, 2020 WL 2113642, at *2 (D.N.H. May 4, 2020)), cert.
granted before judgment sub nom., Trump v. Barbara, 146 S. Ct. 879 (2025); Escobar Molina v. U.S. Dep’t of
Homeland Sec., 811 F. Supp. 3d 1 (D.D.C. 2025) (“‘Provisional certification does not lessen the rigor of Rule 23,’ but
the court proceeds with the understanding that ‘[a]n order that grants . . . class certification may be altered or amended
before final judgment.’”) (alterations in original) (citation omitted) (first quoting L.G.M.L. v. Noem, 800 F. Supp. 3d
100, 117 (D.D.C. 2025); then quoting FED. R. CIV. P. 23(c)(1)(C)).
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mean that they have conducted a less-rigorous certification analysis, but instead use the
“provisional” designation to signal that the certification order may be of limited duration.87
Some legal scholars have expressed concern that courts may use expedited class certification as a
shortcut around Rule 23’s requirements.88 For example, one scholar has stated that provisional
class certification “appears to be a quick-and-dirty assessment of whether [the court] thinks the
class certification criteria are met so that it can enter a preliminary injunction on behalf of the
class.”89 Relatedly, Justice Alito emphasized in his concurrence in CASA that district courts
should not view CASA “as an invitation to certify nationwide classes without scrupulous
adherence to the rigors of Rule 23.”90 In his view, nationwide injunctions “will return from the
grave under the guise of ‘nationwide class relief’” if district courts “award relief to broadly
defined classes” without adhering to the rule’s procedural protections.91
In addition to expediting class certification for purposes of issuing injunctive relief, courts have in
some cases granted temporary injunctive relief to putative class members without first certifying
a class.92 In one prominent example, A.A.R.P. v Trump, the Supreme Court temporarily enjoined
the government from deporting a putative class of Venezuelan nationals that the government
alleged were members of the organization Tren de Aragua.93 In doing so, the Court’s per curium
opinion explained that the putative class members “are at imminent risk of being classified as
alien enemies and removed from the United States,” and that the Court “may properly issue
temporary injunctive relief to the putative class in order to preserve [the Court’s] jurisdiction.”94
The Court further explained that, because “courts may issue temporary relief to a putative class,”
the Court did “not need to decide whether a class should be certified as to the detainees’ due
process claims in order to temporarily enjoin the Government from removing putative class
members.”95 In a dissenting opinion, Justice Alito argued that it was improper to grant injunctive
relief to putative class members without the plaintiffs first showing “that the standard
requirements for class certification could likely be met.”96
Some legal scholars contend that longstanding legal precedent establishes a court’s authority to
grant injunctive relief to putative class members in order to preserve the status quo until the court
is able to rule on class certification.97 Others have asserted that granting injunctive relief to
87 2 RUBENSTEIN, NEWBERG AND RUBENSTEIN ON CLASS ACTIONS § 4:30 (6th ed.) (“The reason these courts typically
label the result of their certification analysis ‘provisional’ has nothing to do with the rigor that went into entering the
order.”).
88 See, e.g., Elias Neibart, The Rise of the All-Writs-Act-Putative-Class-Injunction?, 77 BAYLOR. L. REV. 681 (2025);
Fitzpatrick, supra note 7.
89 Fitzpatrick, supra note 7.
90 Trump v. CASA, Inc., 606 U.S. 831, 868 (2025) (Alito, J., concurring).
91 Id.
92 See, e.g., A.A.R.P. v. Trump, 605 U.S. 91 (2025); Am. Council of Learned Soc’ys v. McDonald, 792 F. Supp. 3d 448
(S.D.N.Y. 2025), appeal filed, No. 25-1905 (2d Cir. Aug. 8, 2025).
93 A.A.R.P., 605 U.S. 91.
94 Id. at 97.
95 Id. at 98 (citing 2 RUBENSTEIN, supra note 87, § 4:30).
96 Id. at 106 (Alito, J. dissenting).
97 See, e.g., Marcus, supra note 15, at 23 (“Well-established doctrine permits courts to protect [putative class members],
before class certification, with the equivalent of universal preliminary injunctions.”); Mila Sohoni, Guest Post: Mila
Sohoni on Trump v. CASA, DIVIDED ARGUMENT: BLOG (May 17, 2025), https://blog.dividedargument.com/p/guest-postmila-sohoni-on-trump-v [https://perma.cc/GZ9Z-JPJV] (“[C]ourts granted broad-gauged injunctive relief in
representative suits under the older Federal Equity Rules and under the original 1938 version of Rule 23. In these older
cases, ‘plaintiffs did not have to do anything more than allege in their bills of complaint that they were suing on behalf
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putative class members prior to class certification is in tension with the Court’s CASA decision,
which the Court issued the month after ruling in A.A.R.P.98 While the Supreme Court determined
that injunctive relief prior to class certification was necessary to protect the Court’s jurisdiction in
A.A.R.P., where the putative class members faced imminent deportation to a foreign country, it is
unclear whether the Supreme Court would find such relief appropriate in other contexts.99
Accordingly, in light of uncertainty over the extent to which courts may grant injunctive relief to
putative class members, some courts have chosen to conduct class certification proceedings on an
expedited basis rather than issuing relief to putative class members.100 Additionally, since the
A.A.R.P. decision, at least one federal appellate court has stayed a district court’s grant of
preliminary injunctive relief to putative class members where the appellate court determined that
the plaintiffs would not be able to satisfy Rule 23’s class certification requirements.101
Class Actions as an Alternative to Nationwide
Injunctions
To the extent class actions are viewed as an alternative to nationwide injunctions, some observers
have expressed concern that class certification may not always be possible to achieve quickly, or
at all, in some cases in which courts otherwise may have granted a nationwide injunction.102 One
common contention is that federal courts generally have interpreted class certification
requirements more strictly since the early 2010s,103 such as in the Wal-Mart case.104 In addition to
of many other persons, on a question of common interest to all of them, in order to obtain preliminary injunctions
shielding all those absent parties from the law’s enforcement.’”) (quoting Mila Sohoni, The Lost History of the
“Universal” Injunction, 133 HARV. L. REV. 920, 975 (2020)).
98 See, e.g., Mila Sohoni, supra note 97 (observing that “many critics of nationwide injunctions have stated that a court
may not give injunctive relief to absent parties unless a case is certified as a Rule 23(b)(2) class action”); Neibart, supra
note 88, at 703 (“Increasingly, courts have been issuing preliminary relief to non-certified classes . . . . Yet there are
reasons to question its validity.”); Fitzpatrick, supra note 7; 2 RUBENSTEIN, supra note 87, § 4:30 (“[T]he Court’s May
2025 AARP ruling authorizing injunctive relief to putative class members . . . is in some tension with the Court’s June
2025 CASA ruling barring so-called ‘universal injunctions.’”).
99 See, e.g., L.G.M.L. v. Noem, 800 F. Supp. 3d 100, 117 n.3 (D.D.C. 2025) (“Given the Supreme Court’s holding in
A.A.R.P. v. Trump, it is unclear whether the Court must certify the putative class before providing preliminary relief.”);
2 RUBENSTEIN, supra note 87, § 4:30 (observing that “the breadth of the A.A.R.P. holding is somewhat unclear”);
Neibart, supra note 88, at 709 (“In a post-CASA world, if the Court were presented with its own arguments (made in
CASA), it might question and seriously probe the validity of putative class relief.”).
100 See, e.g., L.G.M.L., 800 F. Supp. 3d at 117.
101 See Tincher v. Noem, 164 F.4th 1097, 1099 (8th Cir. 2026) (stating that “the grant of relief to such a broad
uncertified class is just a universal injunction by another name” and that “[e]ven if ‘courts may issue temporary relief to
a putative class,’ this one has no chance of getting certified”).
102 See, e.g., City of Chicago v. Barr, 961 F.3d 882, 917 (7th Cir. 2020) (“The class action mechanism is not an
adequate substitute for a universal injunction in the proper case.”); Malveaux, supra note 15 (“[The] suggestion that
Rule 23(b)(2) provides a ready alternative to the national injunction is flawed.”).
103 See, e.g., Malveaux, supra note 15, at 58; Steve Vladeck, 162. What Does the Birthright Citizenship Ruling
Portend?, ONE FIRST (June 27, 2025), https://www.stevevladeck.com/p/162-what-does-the-birthrightcitizenship [https://perma.cc/R3EP-DWXV] (“Class actions are harder to bring . . . [due to] a series of rulings from the
early 2010s that ratcheted up the requirements for certifying nationwide classes.”); Robert H. Klonoff, The Decline of
Class Actions, 90 WASH. U.L. REV. 729 (2013) (stating that “in recent years courts have cut back sharply on plaintiffs’
ability to bring class action lawsuits”). But see Marcus, supra note 15, at 8–9 (stating that the increased difficulty of
certifying class actions has “almost exclusively entailed cases for monetary relief,” and that the Supreme Court’s
“decisions cabining the class action have little bearing on cases brought against government defendants for injunctive
or declaratory relief”).
104 See discussion on Wal-Mart v. Dukes supra “Class Certification Under Rule 23.”
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the potential difficulty of satisfying Rule 23’s requirements, obtaining class certification can also
be expensive and time-consuming,105 and courts and commentators have raised questions over the
extent to which courts may expedite class certification or grant injunctive relief for putative class
members without first certifying a class.106
In Justice Sotomayor’s dissenting opinion in the CASA case, for example, she stated that class
actions are not a “perfect substitute” for nationwide injunctions.107 While Justice Sotomayor
emphasized that CASA’s limitation of nationwide injunctions left class actions “untouched” as an
“important tool” for obtaining broad injunctive relief,108 she identified a number of reasons that
class actions may not always provide a substitute for nationwide injunctions. For example, she
explained that a plaintiff seeking to challenge government action on behalf of an entire class will
face “the higher cost of pursuing class relief,” the “difficult and time consuming” process of
demonstrating compliance with Rule 23(a)’s prerequisites, and an evidentiary standard requiring
“hearings and sometimes significant amounts of evidence on the merits of the class before
certifying the class.”109
In contrast, some legal scholars contend that obtaining certification for a class seeking injunctive
relief against the government is generally not as difficult as other commentators have
suggested.110 For instance, one scholar has asserted that class actions remain a “potent and viable
substitute” for nationwide injunctions, and that “federal courts have overwhelmingly favored
class certification” in cases challenging “uniform, across-the board policies whose legality can be
determined for everyone at once.”111
The prospect of using class actions as a substitute for nationwide injunctions has also raised
concerns that district courts may become too permissive in certifying class actions that challenge
government policies after CASA.112 In Justice Alito’s concurring opinion in CASA, for instance, he
observed that “Rule 23 may permit the certification of nationwide classes in some discrete
scenarios,” but he cautioned that “[l]ax enforcement” of class certification standards could “create
a potentially significant loophole” around CASA’s limitations on nationwide injunctions.113
Plaintiffs have obtained broad, classwide injunctions in a number of cases challenging
government actions since the Supreme Court’s CASA ruling.114 It remains to be seen how the
105 See, e.g., Maureen Carroll, Aggregation for Me, but Not for Thee: The Rise of Common Claims in Non-Class
Litigation, 36 CARDOZO L. REV. 2017, 2021–24 (2015) (“Notwithstanding the availability of Rule 23(b)(2), plaintiffs
currently face a set of structural disincentives to class treatment that cause many of them to choose the individual
form.”); Frost, supra note 15, at 1095–97.
106 See supra “Preliminary Injunctive Relief in Class Actions.”
107 Trump v. CASA, Inc., 606 U.S. 831, 919 (2025) (Sotomayor, J. dissenting).
108 Id. (“[T]he majority leaves untouched one important tool to provide broad relief to individuals subject to lawless
Government conduct: Rule 23(b)(2) class actions for injunctive relief.”).
109 Id.
110 Fitzpatrick, supra note 7 (“Although some commentators have worried that it will be too difficult to certify class
actions, the truth is that it is relatively easy to certify class actions that seek injunctive relief: the certification criteria
are less numerous and less demanding than for class actions seeking money damages.”).
111 Marcus, supra note 15, at 23.
112 See, e.g., Fitzpatrick, supra note 7; Neibart, supra note 88.
113 Trump v. CASA, Inc., 606 U.S. 831, 868 (2025) (Alito, J., concurring).
114 See, e.g., Barbara v. Trump, 790 F. Supp. 3d 80, 90 (D.N.H. 2025); CASA, Inc. v. Trump, 793 F. Supp. 3d 703 (D.
Md. 2025); L.G.M.L. v. Noem, 800 F. Supp. 3d 100, 117 (D.D.C. 2025) (granting preliminary injunction and certifying
class of “all unaccompanied alien children from Guatemala in (and who will be in) [Office of Refugee Resettlement]
custody who have not received a final order of removal or the Attorney General’s permission to voluntarily depart
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Supreme Court may respond as more such cases work through the judicial system, and the extent
to which class actions may prove to be a substitute for nationwide injunctions after CASA remains
subject to ongoing debate.115
Considerations for Congress
Nationwide injunctions have been the subject of substantial attention from the 119th Congress.116
On April 9, 2025, the House passed H.R. 1526, the No Rogue Rulings Act (NORRA) of 2025.
The bill would limit the authority of federal district courts to issue injunctions. It would provide
that federal district courts could generally only issue injunctive relief “to limit the actions of a
party to the case . . . with respect to the party seeking injunctive relief from such district court and
non-parties represented by such a party acting in a representative capacity pursuant to the Federal
Rules of Civil Procedure.” As an exception to that limitation, the bill would allow a three-judge
district court to issue broader injunctive relief “[i]f a case is brought by two or more States
located in different circuits challenging an action by the executive branch.”
While the Supreme Court’s CASA decision limited the ability of federal courts to issue nationwide
injunctions, the decision did not change the law with respect to federal courts’ ability to issue
classwide injunctive relief. Given that a classwide injunction can be functionally equivalent to a
nationwide injunction, some legal scholars have observed that nationwide class actions against
the government may implicate similar policy concerns as nationwide injunctions in certain
respects.117 For instance, proponents of nationwide class actions have argued that such lawsuits
provide a beneficial mechanism for protecting large groups against unlawful government actions,
while avoiding the need for each affected individual or entity to actively obtain legal
representation and participate in litigation.118 Critics of nationwide class actions have argued that
granting injunctive relief against the government with respect to a nationwide class may
improperly expand the legal effect of lower court rulings and result in a number of negative
consequences, such as preventing important legal issues from percolating across different
courts.119
In light of the increased focus on class actions as a potential substitute for nationwide injunctions,
Congress may choose to monitor the use of the class action device in lawsuits seeking injunctive
relief against the government, and evaluate whether such use aligns with Congress’s preferences.
If Congress wished, it could consider legislating to expand or limit the ability of plaintiffs to
under 8 U.S.C. § 1229c and applicable regulations.”); Escobar Molina v. U.S. Dep’t of Homeland Sec., 811 F. Supp. 3d
1, 27 (D.D.C. 2025) (granting preliminary injunction and certifying class of “[a]ll persons who, since August 11, 2025,
have been or will be arrested in [the District of Columbia] for alleged immigration violations without a warrant and
without a pre-arrest, individualized assessment of probable cause that the person poses an escape risk.”).
115 See, e.g., Marcus, supra note 15, at 23; Fitzpatrick, supra note 7.
116 Some Members of the 119th Congress have introduced legislation that would regulate nationwide injunctions. See,
e.g., H.R. 1526, 119th Cong. (2025) (as passed by the House); S. 1206, 119th Cong. (2025) (as introduced). The House
and Senate Judiciary committees also held hearings on nationwide injunctions in April 2025. Judicial Overreach and
Constitutional Limits on the Federal Courts: Hearing Before the H. Comm. on the Judiciary, Subcommittee on Courts,
Intellectual Property, Artificial Intelligence, and the Internet, 119th Cong. (2025); Rule by District Judges II:
Exploring Legislative Solutions to the Bipartisan Problem of Universal Injunctions: Hearing Before the S. Comm. on
the Judiciary, 119th Cong. (2025).
117 See, e.g., Marcus, supra note 15, at 31; Fitzpatrick, supra note 7. For an in-depth discussion of legal and policy
debates over nationwide injunctions, see CRS Report R46902, Nationwide Injunctions: Law, History, and Proposals
for Reform, by Joanna R. Lampe (2021).
118 See Marcus, supra note 15, at 4–7.
119 See Morley, supra note 72, at 625.
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bring suits challenging government policies on a class action basis. For example, a legal scholar
has argued that Congress should enact legislation making it less difficult to obtain certification of
nationwide classes in lawsuits challenging government policies.120 Another legal scholar has
proposed amending Rule 23 to impose geographic limitations on classes certified in such
lawsuits.121
Congress has substantial constitutional authority to regulate federal court procedures, including
the procedures that apply to class action lawsuits.122 In the Rules Enabling Act, Congress
authorized the Supreme Court to create and amend federal court procedural rules, such as Rule
23’s class action procedures, and also imposed congressional oversight on the rulemaking
process.123 Congress also may enact legislation directly governing class actions,124 and Congress
has enacted legislation limiting or promoting use of the class action device in various contexts.125
Congress’s ability to expand the use of class action lawsuits is subject to constitutional
constraints. For example, Article III of the Constitution limits the jurisdiction of federal courts to
resolving cases in which a plaintiff has standing—meaning a sufficient personal stake in the
outcome of the litigation—and Congress may not expand federal courts’ jurisdiction beyond
Article III’s limits.126 Class actions also implicate the absent class members’ constitutional due
process rights,127 and courts have observed that Rule 23’s procedural safeguards are in part
designed to protect those rights, such as by requiring that class representatives will adequately
represent the absent class members’ interests.128
120 See Steve Vladeck, Bonus 136: Nationwide Injunctions vs. Nationwide Class Actions, ONE FIRST (Apr. 3,
2025), https://www.stevevladeck.com/p/bonus-136-nationwide-injunctions [https://perma.cc/JJM3-97N3].
121 See Michael T. Morley, Disaggregating Nationwide Injunctions, 71 Ala. L. Rev. 1, 53 (2019).
122 See Hanna v. Plumer, 380 U.S. 460, 472 (1965) (“[T]he constitutional provision for a federal court system
(augmented by the Necessary and Proper Clause) carries with it congressional power to make rules governing the
practice and pleading in those courts . . . .”). For further discussion of Congress’s authority to make rules governing
federal court procedures, see CRS In Focus IF11557, Congress, the Judiciary, and Civil and Criminal Procedure, by
Joanna R. Lampe (2020); Lib. of Cong., Inherent Powers Over Judicial Procedure, CONSTITUTION ANNOTATED,
https://constitution.congress.gov/browse/essay/artIII-S1-4-2/ALDE_00013521/ (last visited Mar. 30, 2026).
123 28 U.S.C. §§ 2071–2077. For further discussion of the Rules Enabling Act, see Lampe, supra note 122.
124 See, e.g., Class Action Fairness Act of 2005, P.L. 109-2, 119 Stat. 4.
125 See, e.g., 8 U.S.C. § 1252(e)(1)(B) (divesting federal courts of authority to certify a class under Rule 23 in certain
cases challenging immigration-related removal orders issued under 8 U.S.C. § 1225(b)); Ending Forced Arbitration of
Sexual Assault and Sexual Harassment Act of 2021, P.L. 117-90, § 2(a), 136 Stat. 26, 26 (2022) (permitting persons
who allege a sexual harassment or sexual assault dispute to, among other things, invalidate agreements that waive their
right to participate in a class action related to such disputes).
126 See TransUnion LLC v. Ramirez, 594 U.S. 413, 423 (2021) (“Article III confines the federal judicial power to the
resolution of ‘Cases’ and ‘Controversies.’ For there to be a case or controversy under Article III, the plaintiff must have
a ‘personal stake’ in the case—in other words, standing.”) (quoting Raines v. Byrd, 521 U.S. 811, 819 (1997)). To
establish standing for purposes of Article III, “a plaintiff must show (i) that he suffered an injury in fact that is concrete,
particularized, and actual or imminent; (ii) that the injury was likely caused by the defendant; and (iii) that the injury
would likely be redressed by judicial relief.” Id.
127 See Phillips Petroleum Co. v. Shutts, 472 U.S. 797, 812 (1985) (“[T]he Due Process Clause of course requires that
the named plaintiff at all times adequately represent the interests of the absent class members.”).
128 See, e.g., Berger v. Compaq Comput. Corp., 257 F.3d 475, 481 (5th Cir. 2001) (stating that Rule 23’s adequacy
requirement has “constitutional dimensions” and “implicates the due process rights of all members who will be bound
by the judgment”); In re Gen. Motors Corp. Pick-Up Truck Fuel Tank Prods. Liab. Litig., 55 F.3d 768, 796 (3d Cir.
1995) (“The Rule 23(a) class inquiries . . . constitute a multipart attempt to safeguard the due process rights of
absentees.”).
Congressional Research Service
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Class Action Lawsuits and Classwide Injunctive Relief
Author Information
Bryan L. Adkins
Legislative Attorney
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Congressional Research Service
R48972 · VERSION 2 · NEW
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