What specific court cases have enjoined presidential troop deployments under the Insurrection Act in the 20th and 21st centuries?
Executive summary
Federal courts in the 20th century rarely enjoined presidential uses of the Insurrection Act, which was instead used to enforce federal desegregation orders and to quell major riots (e.g., Eisenhower in Little Rock, George H.W. Bush in 1992) [1] [2]. In the 21st century, litigation has produced preliminary judicial blocks and injunctions related to attempted deployments—most notably litigation in California and Illinois where federal judges limited or blocked deployments and a district judge in California found unlawful Posse Comitatus Act violations related to Guard activities [3] [4] [5].
1. What the Insurrection Act authorizes and why courts matter
The Insurrection Act (10 U.S.C. §§ 251–255) is a narrow statutory exception to Posse Comitatus that permits the president to use federal troops to enforce federal law, suppress insurrection, or protect constitutional rights when state authorities cannot or will not do so; its standards are contested and courts are a principal venue for resolving those contests [6] [3]. Legal commentators and the Brennan Center emphasize that the Act’s vague triggers, combined with precedents like Martin v. Mott, leave significant presidential discretion that courts must interpret when plaintiffs challenge deployments [1] [6].
2. The 20th century: deployments enforced, not typically enjoined
Throughout the 20th century presidents invoked the Act to enforce desegregation and to respond to major civil unrest—Dwight D. Eisenhower federalized troops for Little Rock school integration and federal responses were used in the civil rights era and during the 1992 Los Angeles riots—actions that were implemented to carry out federal court or executive decisions rather than routinely enjoined by courts [1] [2] [7]. Reporting and historical summaries in the Brennan Center and encyclopedic entries document these deployments but do not identify a pattern of courts issuing pre-deployment injunctions in those 20th-century instances [1] [2].
3. 21st‑century litigation that produced blocks or findings against deployments
In recent years litigation has directly targeted attempted deployments and produced court orders limiting or pausing troop movements: federal judges granted or maintained injunction-like relief blocking National Guard deployments to cities such as Portland and Chicago during the 2025–2026 controversies, and an appeals court paused a three-judge panel’s earlier ruling that would have allowed deployment—actions that demonstrate courts can and did intervene to prevent or constrain federal troop deployments in the 21st century [4] [8] [5]. In State of California v. Trump, Judge Stephen Breyer (as referenced in legal commentary) found that Guard activities in Los Angeles had crossed into unlawful law-enforcement conduct under Posse Comitatus, a factual-legal finding that underpinned judicial intervention against particular deployments [3].
4. Legal themes courts are deciding — standards, Posse Comitatus, and “regular forces”
Contemporary litigation hinges on whether the statutory predicates of sections 252–253 are satisfied, whether Guard or active-duty forces are acting as “regular forces” or state Guard units, and whether the Posse Comitatus Act’s limits have been breached; scholars and practitioners point to the 1908 Act distinctions and recent supplemental briefing in the Illinois National Guard litigation as focal legal arguments that could sustain injunctions or affirm executive authority depending on the court’s interpretation [9] [6] [3]. The Brennan Center and legal commentators warn that the Act’s ambiguous triggers create room for divergent judicial outcomes and competing political agendas to influence litigation strategy [1] [9].
5. What is missing and how to read the record
Available reporting and legal summaries identify specific modern cases and judicial actions that blocked or constrained deployments (California litigation, Illinois/Chicago National Guard proceedings, paused appeals decisions), but they do not provide a comprehensive catalog of every injunction in the 20th and 21st centuries; historical narratives emphasize use rather than litigation outcomes, so an exhaustive list of court-ordered enjoinments cannot be compiled from these sources alone [1] [4] [3]. Readers should therefore treat cited examples as documented instances where courts intervened or made dispositive findings about deployments, while recognizing that the sources do not claim to be an authoritative, complete register of all injunctions over the two centuries [1] [3].