Federal Judge Rules Trump's Use of Troops in Los Angeles Violated the Posse Comitatus Act

On September 2, 2025, U.S. District Judge Charles Breyer ruled that the administration's use of federalized National Guard soldiers and Marines in Los Angeles violated the Posse Comitatus Act of 1878, which bars the military from civilian law enforcement. Breyer found that troops had engaged in security patrols, riot control, arrests, searches and crowd control, and rejected the government's argument that a constitutional exception permitted it. He wrote that the deployment's effect was to create a national police force with the president as its chief. His order barring those activities in Los Angeles was set to take effect September 12.

The Posse Comitatus Act is one of the few statutory limits on domestic use of federal military force, and the ruling was among the first modern findings that a president's deployment crossed it. The dispute goes to a basic allocation of authority: whether the commander in chief may convert soldiers into a general-purpose domestic police reserve without congressional authorization, and whether governors and courts retain any check once a deployment is federalized.

The administration appealed, and at the time of the ruling it was publicly weighing similar deployments in other cities. The injunction was limited to Los Angeles and did not resolve when federalized troops may be used domestically.