Justice Barrett’s majority opinion in Trump v. CASA, Inc. is a watershed moment, not for its ruling on birthright citizenship—which it conspicuously avoided—but for its definitive methodological statement on the scope of federal equitable power. The opinion cements a rigid historical formalism that effectively freezes the remedial capacity of the federal courts to the practices of 1789. This decision represents the culmination of the jurisprudential trend foreshadowed by Grupo Mexicano de Desarrollo, S. A. v. Alliance Bond Fund, Inc. (1999), extending the originalist methodology now prevalent in substantive constitutional interpretation—the so-called Bruen-ization of the law—to the historically flexible domain of equity. The result is a significant retrenchment of the judiciary’s ability to provide systemic relief against unlawful executive action.
The analytical foundation of the opinion is the assertion that the Judiciary Act of 1789, by granting jurisdiction over “all suits… in equity,” incorporated only those remedies “traditionally accorded by courts of equity” at the Founding. Justice Barrett deploys this standard not as a guiding principle but as a strict historical boundary. While the majority concedes that “equity is flexible,” it immediately cabins this flexibility, insisting it is “confined within the broad boundaries of traditional equitable relief.” In application, however, these boundaries prove exceedingly narrow, demanding a clear Founding-era antecedent for any modern remedy.
This methodology represents a categorical rejection of the concept of equity as an evolving system designed to adapt to novel injustices and the complexities of modern governance. The majority prioritizes historical form over equitable function. The inherent purpose of equity—to provide relief where rigid legal forms are inadequate—is subordinated to a historical cataloging exercise. If a remedy, such as the universal injunction, was “conspicuously nonexistent for most of our Nation’s history,” its utility in the modern administrative state is deemed irrelevant. Policy arguments, the majority insists, are “beside the point.”
The majority’s treatment of the “bill of peace” is illustrative of this rigid approach. Respondents argued that the bill of peace, which allowed Chancery courts to resolve disputes affecting numerous individuals without formal joinder, served as an analogue. Justice Barrett dismisses this by focusing on the procedural differences: the bill of peace involved “small and cohesive” groups and bound absent members, whereas universal injunctions affect diffuse populations and only bind the defendant. This analysis elevates technical distinctions over the shared functional goal of providing efficient, broad-based resolution to common legal questions.
Crucially, the majority identifies the modern Rule 23 class action as the sole legitimate descendant of the bill of peace. This move is strategic. By characterizing the universal injunction as a “shortcut” that impermissibly “circumvent[s] Rule 23’s procedural protections,” the Court frames the issue not as one of judicial power, but of procedural irregularity. It suggests that Rule 23 occupies the entire field of aggregate relief derived from the bill of peace, thereby foreclosing equitable innovations outside the Rule’s stringent requirements. This effectively transforms Rule 23 from a permissive procedural pathway into a substantive limit on the inherent scope of equitable authority.
The implications of this historical formalism are profound in the context of the administrative state. Modern executive action, through regulation or executive order, often operates on a nationwide, immediate scale unimaginable in 1789. The universal injunction evolved, albeit recently, as a judicial response calibrated to the scope of this modern executive power. By tethering the judiciary’s remedial toolkit to the pre-administrative era, the majority guarantees a mismatch between the scope of the alleged legal violation and the scope of the remedy.
This mismatch ensures remedial under-protection, forcing a retail model of litigation to address wholesale constitutional or statutory violations. While mechanisms like Rule 23 remain, they are often cumbersome, expensive, and ill-suited for emergency litigation where irreparable harm is imminent. The decision thus elevates historical purity over the functional necessity of checking potentially unlawful executive action at the scale at which it occurs.
The most significant unresolved tension lies in Footnote 10, which explicitly reserves the question of Administrative Procedure Act (APA) vacatur under 5 U.S.C. § 706(2). This reservation may prove to be the exception that swallows the rule. If the statutory authority to “set aside” agency action is interpreted as authorizing universal vacatur, the practical impact of CASA may be significantly muted in challenges to agency rulemaking. However, the logic of CASA casts a shadow over APA vacatur. If the Court applies the same historical lens, arguing that statutory remedies must conform to traditional equitable constraints, the judiciary’s capacity to provide systemic relief will be almost entirely neutralized.
Trump v. CASA signals a judiciary retreating from its capacity to provide comprehensive checks on executive power. By imposing the rigid methodology of Bruen onto the realm of equity, the majority significantly shifts the balance of power toward the executive branch, ensuring that challenges to federal policy will be piecemeal, protracted, and often incomplete.