Second Circuit Endorses Munsingwear Vacatur on Joint Motion When Mootness Is Not Fairly Attributable to Appellants

I. Introduction

Am. Ass'n of Univ. Professors v. U.S. Dep't of Just. (2d Cir. May 14, 2026) arose from a high-profile funding dispute involving Columbia University. Two labor organizations—the American Association of University Professors and the American Federation of Teachers (together, the “Union Plaintiffs”)—sued multiple federal agencies and officials after the Government terminated approximately $400 million in federal funding to Columbia and demanded “comprehensive programmatic and structural changes.” Columbia was not a party.

In the district court (S.D.N.Y.), the Union Plaintiffs sought (among other relief) restoration of funding, injunctions barring the Government’s reform demands, prospective protection against termination of additional funding, and damages. The district court denied a preliminary injunction and dismissed the action for lack of Article III standing. While the appeal was pending, the Government and Columbia executed an agreement restoring most funding and committing Columbia to reforms. The parties then filed a joint motion in the Second Circuit to (1) dismiss the appeal as moot, (2) vacate the district court’s order, and (3) remand with instructions to dismiss as moot.

The panel majority (Judges Chin and Kahn) granted all relief; Judge Menashi dissented as to vacatur. The key legal issue became not the merits of standing, but the remedial consequence of mootness on appeal: whether vacatur should follow when mootness results from changed circumstances connected to a third-party agreement and the appellants’ subsequent withdrawal of remaining claims.

II. Summary of the Opinion

The Second Circuit:

• Dismissed the appeal as moot under the principle that a case is moot when it is “impossible for a court to grant any effectual relief whatever.”
• Vacated the district court’s order under the federal “Munsingwear practice,” reasoning that the appeal became moot for reasons “not fairly attributable” to the Union Plaintiffs.
• Remanded with instructions to dismiss the case as moot.

The majority treated vacatur as the default where mootness prevents appellate review and where the equities—especially “fault” for mootness—favor the appellant. Judge Menashi agreed mootness required dismissal but argued that vacatur was improper because, on the majority’s own assumption, mootness occurred when the Union Plaintiffs voluntarily withdrew remaining requests for relief, making the case analogous to abandonment (and, in relevant respects, to settlement-based mootness).

III. Analysis

A. Precedents Cited

1. Mootness doctrine (dismissal)

• Doe v. McDonald, 128 F.4th 379 (2d Cir. 2025): cited for the core definition—mootness exists when it is “impossible … to grant any effectual relief whatever.” The panel used this to justify dismissal without resolving the precise moment mootness occurred.
• Town of Newburgh v. Newburgh EOM LLC, 151 F.4th 96 (2d Cir. 2025): invoked for the proposition that an appeal becomes moot when the relief sought is “no longer needed.” This supports the practical, relief-centered approach the majority adopted once the Columbia–Government agreement altered the real-world stakes.
• Fed. R. App. P. 42(b): provides the procedural vehicle for dismissal on the parties’ motion.

2. The “Munsingwear practice” (vacatur when mootness blocks review)

• United States v. Munsingwear, Inc., 340 U.S. 36 (1950): the foundational rule—when mootness prevents appellate review, the “established practice” is to vacate and remand with directions to dismiss, preventing unreviewable judgments from “spawn[ing] any legal consequences” and “clear[ing] the path for future relitigation.” The majority treats this as the governing baseline.
• Arizonans for Off. Eng. v. Arizona, 520 U.S. 43 (1997): reinforces Munsingwear’s “established practice” and cautions against allowing a party to retain the benefit of a favorable judgment after mooting the dispute through voluntary action. The majority used it to distinguish this case: the Union Plaintiffs lost below and were not trying to preserve a favorable judgment.
• Acheson Hotels, LLC v. Laufer, 601 U.S. 1 (2023): cited to underscore that the Munsingwear practice is “well settled” and that voluntary action does not automatically bar vacatur where the party did not abandon the case to evade review. The majority analogized the Union Plaintiffs’ withdrawal of relief to a non-evasive response to changed circumstances.
• Camreta v. Greene, 563 U.S. 692 (2011): supports vacatur where mootness prevents review of a “legally consequential decision,” highlighting the systemic concern with leaving potentially influential rulings unreviewed.

3. Equitable limits on vacatur: “fault” for mootness

• Azar v. Garza, 584 U.S. 726 (2018) (per curiam): emphasized that vacatur depends on equitable considerations and “conditions and circumstances.” The majority uses this to frame vacatur as discretionary yet guided by structured equity.
• FDIC v. Regency Sav. Bank, F.S.B., 271 F.3d 75 (2d Cir. 2001) (per curiam): central to the majority’s test: the “touchstone” is the appellant’s “fault in causing mootness.”
• U.S. Bancorp Mortg. Co. v. Bonner Mall P'ship, 513 U.S. 18 (1994): provides the canonical limitation: when mootness results from settlement, vacatur is typically unwarranted because the losing party “voluntarily forfeited” review. The majority cites Bancorp for the “vagaries of circumstance” formulation and for the proposition that vacatur is not categorically barred even when settlement causes mootness if “exceptional circumstances” exist.
• Hassoun v. Searls, 976 F.3d 121 (2d Cir. 2020): the Second Circuit’s modern application of fault-based equity, granting vacatur where mootness resulted from “good faith” actions and external circumstances rather than strategic abandonment. The majority relied on Hassoun both for the general standard and for the idea that vacatur may be appropriate where it “harms neither party.”
• Bragger v. Trinity Cap. Enter. Corp., 30 F.3d 14 (2d Cir. 1994): quoted for the “general duty to vacate and dismiss” when circumstances beyond the appellant’s control render the case moot.

4. Second Circuit-specific vacatur considerations and strategic mooting

• Newburgh EOM LLC, 151 F.4th 96 (2d Cir. 2025) and Russman v. Bd. of Educ. of Enlarged City Sch. Dist. of City of Watervliet, 260 F.3d 114 (2d Cir. 2001): cited for the characterization of vacatur as the “default rule” and that courts have been “liberal” in granting it in the ordinary run of cases.
• Exxon Mobil Corp. v. Healey, 28 F.4th 383 (2d Cir. 2022) and Blackwelder v. Safnauer, 866 F.2d 548 (2d Cir. 1989): used to distinguish between unilateral abandonment and mootness to which multiple actors contributed. The majority used these cases to treat the Columbia–Government agreement as a substantial driver of mootness even if the formal step to mootness was the Union Plaintiffs’ withdrawal of relief.
• Major League Baseball Props., Inc. v. Pac. Trading Cards, Inc., 150 F.3d 149 (2d Cir. 1998): supports the view that the primary “public interest” cost of vacatur is leaving an issue for future litigation, which may be outweighed by preventing unreviewable decisions from having continuing effect.
• Long Island Lighting Co. v. Cuomo, 888 F.2d 230 (2d Cir. 1989) and Manufacturers Hanover Tr. Co. v. Yanakas, 11 F.3d 381 (2d Cir. 1993): invoked to reject a rigid rule against vacatur where parties jointly seek it, and to note that even in settlement contexts vacatur has sometimes been ordered.

5. Authorities emphasized in the dissent

• Karcher v. May, 484 U.S. 72 (1987): a key dissent anchor for the principle that when the losing party “declined to pursue its appeal,” Munsingwear is “inapplicable,” treating the case as though no appeal had been taken.
• Chapman v. Doe, 143 S. Ct. 857 (2023) (Jackson, J., dissenting): cited for the proposition that equities “generally do not favor” vacatur when the requesting party played a role in mooting the case.
• NYCLU v. Grandeau, 528 F.3d 122 (2d Cir. 2008) and Etuk v. Slattery, 936 F.2d 1433 (2d Cir. 1991): cited to stress that mootness is a legal determination not controlled by party stipulation.
• Mahoney v. Babbitt, 113 F.3d 219 (D.C. Cir. 1997): relied on (via Hassoun discussion) to argue vacatur is inappropriate where a judgment poses “little risk of prejudice” or legal consequence for the parties.

B. Legal Reasoning

The majority’s reasoning proceeds in two steps.

1. Mootness: relief-centered, timing-agnostic

The panel declined to decide whether mootness occurred at the moment of the Columbia–Government agreement or later when the Union Plaintiffs withdrew their remaining claims. It treated the timing dispute as non-dispositive because, under Doe v. McDonald and Town of Newburgh v. Newburgh EOM LLC, the dispositive question is whether any “effectual relief” remains. With the challenged funding largely restored and the Union Plaintiffs no longer pursuing prospective equitable relief or damages, no effective appellate relief remained, so dismissal followed.

2. Vacatur: default rule plus a “not fairly attributable” equity finding

On vacatur, the majority framed the governing law as a strong presumption: when a case becomes moot pending appeal, Munsingwear vacatur is the established practice. But it also acknowledged (via Azar v. Garza, FDIC v. Regency Sav. Bank, F.S.B., and U.S. Bancorp Mortg. Co. v. Bonner Mall P'ship) that vacatur is an equitable determination where the appellant’s fault is central.

The key move is the majority’s attribution analysis. Even assuming the case became moot only when the Union Plaintiffs withdrew their remaining requests for relief, the majority treated that withdrawal as a response to the agreement between the Government and a third party (Columbia) that had “already accomplished the lawsuit’s chief goals” (restoration of funding). In that posture, the Union Plaintiffs were not viewed as strategically abandoning review; instead, the controversy was rendered practically obsolete by external developments to which both the Government and Columbia “played a role.”

The majority also found vacatur equitable because:

• It prevents an unreviewable standing decision from “spawning any legal consequences” (Munsingwear).
• It “harms neither party” where both request it (Hassoun v. Searls).
• The public interest cost—leaving the standing issue for future litigation—is acceptable (Major League Baseball Props., Inc.).
• Refusing vacatur could incentivize district-court winners to “all but moot” cases on appeal to preserve favorable rulings without appellate review (a systemic fairness rationale consistent with the Munsingwear tradition).

3. The dissent’s contrary equity model: abandonment bars Munsingwear

Judge Menashi accepted mootness but rejected vacatur because (on the majority’s own assumption) mootness resulted from the Union Plaintiffs’ voluntary withdrawal of claims—i.e., abandonment of appellate review. Drawing on Karcher v. May and U.S. Bancorp Mortg. Co. v. Bonner Mall P'ship, the dissent reasoned that when a losing party could obtain review “by appeal as of right” but chooses not to, Munsingwear is inapplicable: the judgment is not “unreviewable,” but “unreviewed by [the party’s] own choice.”

The dissent also criticized the majority for treating party stipulations about attribution as persuasive, emphasizing that mootness (and the equities of vacatur) are legal determinations not controlled by agreement. Finally, the dissent argued the parties did not show concrete harms from leaving the district court’s standing order in place—suggesting vacatur should not be granted as a routine eraser of precedent absent demonstrated prejudice.

C. Impact

This decision is likely to matter less for the underlying Columbia funding dispute (which the court did not reach) and more for appellate remedial practice in public-law litigation:

• Strengthening vacatur as the “default” on mootness pending appeal: The majority’s framing (vacatur is ordinarily granted) reinforces that litigants should expect vacatur when external events extinguish live controversies during appeal.
• Expanded pathway to vacatur where third-party actions change the case’s practical posture: Even if appellants take the formal step that moots the case (withdrawing claims), the majority suggests vacatur may still be equitable if that step is plausibly driven by material third-party developments (here, a Government–nonparty agreement restoring the core practical relief).
• Greater weight for joint positions on attribution: While the court acknowledged it is not bound by stipulations, it expressly saw “no reason to disregard” the parties’ agreement that mootness was “not fairly attributable” to appellants—potentially encouraging coordinated vacatur requests in future politically salient disputes.
• Reduced staying power of district-court standing dismissals in mooted, fast-moving disputes: Plaintiffs facing an adverse standing ruling may be more able to avoid lingering preclusive or persuasive effects if the controversy is overtaken by external events and the parties jointly seek vacatur.
• A clear fault-line for future panels: The dissent supplies a ready doctrinal counterweight—treating appellant withdrawal as disqualifying “abandonment” under Karcher/Bancorp. Future cases will likely litigate how directly the appellant’s own choices caused mootness and what qualifies as “not fairly attributable.”

IV. Complex Concepts Simplified

• Mootness: Federal courts can decide only live disputes. If events occur such that the court can no longer grant meaningful relief, the case is moot and must be dismissed.
• Standing (Article III): The constitutional requirement that the plaintiff have a personal, legally cognizable injury traceable to the defendant and redressable by the court. The district court held the unions lacked standing because the funding belonged to Columbia (a nonparty), and the unions were not the direct recipients.
• Vacatur: An appellate order nullifying (“wiping out”) a lower court’s judgment. It prevents the judgment from having ongoing legal effects when appellate review becomes impossible.
• Munsingwear vacatur: The traditional practice of vacating lower-court judgments when a case becomes moot on appeal through happenstance or actions not fairly attributable to the appellant.
• Bancorp limitation (settlement/abandonment): When the losing party itself causes mootness by settling or abandoning review, vacatur is usually disfavored because the party chose to forgo appellate correction.
• “Fault” / “fair attribution”: The equity inquiry into who caused mootness and why. The majority treated the third-party agreement and resulting changed circumstances as the principal drivers; the dissent treated the appellants’ withdrawal as the decisive cause.

V. Conclusion

The Second Circuit’s decision establishes a practical, equity-weighted approach to vacatur on mootness: where a case becomes moot on appeal in circumstances the parties jointly characterize as not fairly attributable to the appellants—particularly where third-party actions have effectively delivered the core practical relief—vacatur remains the presumptive outcome under Munsingwear.

The dissent underscores a competing principle: vacatur should not function as an after-the-fact mechanism to erase adverse rulings when the losing party voluntarily withdraws its claims and thereby renders the case moot. The resulting tension—between vacatur-as-default to prevent unreviewable judgments from having lingering effects, and vacatur-as-exception withheld when the appellant “abandons” review—will likely shape future Second Circuit disputes about strategic mooting, settlement-adjacent resolutions, and the afterlife of standing decisions.