Trump v. Casa Inc.

Majority reasoning

Justice Barrett, writing for the majority, reasoned that the Judiciary Act of 1789 only grants federal courts the equitable remedies that were traditionally available in English courts of equity at the time of the founding, and that nationwide injunctions have no such historical pedigree. Suits in equity were historically brought by and against individual parties, with remedies limited to those parties, and universal injunctions did not appear in American courts until the 20th century and remained rare until recently. The majority rejected the argument that "bills of peace" (a historical group litigation device) or the "complete relief" principle justify universal injunctions, explaining that complete relief means only relief necessary for the actual plaintiffs, not relief benefiting the whole public. The majority found the government likely to suffer irreparable harm from injunctions exceeding this authority, since such injunctions improperly intrude on a coexisting branch of government by blocking enforcement against nonparties. The majority left open whether narrower relief could still give the state plaintiffs "complete relief" given their claimed administrative and financial burdens, sending that question back to the lower courts, and explicitly did not address whether the birthright citizenship order itself is constitutional.

Dissent reasoning

Justice Sotomayor, joined by Justices Kagan and Jackson, argued that the executive order is patently unconstitutional under the Fourteenth Amendment's text, history, and precedent including United States v. Wong Kim Ark, and that the government could show no irreparable harm from being blocked from enforcing a plainly illegal policy. She argued equity has always been flexible and historically included remedies like bills of peace and taxpayer suits that benefited nonparties, so the majority's rigid historical test misreads equity's nature. She contended the lower courts correctly found that only nationwide injunctions could give the individual, organizational, and state plaintiffs complete relief, given cross-state movement of families and administrative burdens, and that the government's proposed narrower alternatives were unworkable and legally incompatible with federal benefits statutes. Justice Jackson, dissenting separately, argued the majority's focus on technical equity doctrine obscures the basic question of whether courts can order the Executive to follow the law at all, and warned that limiting judicial remedies to named plaintiffs creates a "zone of lawlessness" where the government can violate the constitutional rights of anyone who hasn't yet sued, disproportionately harming poor and unrepresented people.