A federal judge in San Francisco has ruled that President Donald Trump and Defense Secretary Pete Hegseth violated federal law by using thousands of California National Guard members and U.S. Marines to support law enforcement in Los Angeles during immigration operations in June.

U.S. District Judge Charles Breyer found the deployment violated the Posse Comitatus Act of 1878, which prohibits the military from performing civilian law enforcement duties. In a 52-page opinion, he also ruled that the administration exceeded the limits of presidential authority under the Constitution by federalizing the California National Guard without proper justification.

California had argued that the deployment undermined state sovereignty and breached the 10th Amendment, which reserves certain powers to the states. Breyer agreed, noting that local agencies such as the Los Angeles Police Department and the Sheriff’s Department maintained order during the demonstrations, despite incidents of violence and property damage. He concluded there was no evidence of a “rebellion” that would allow the president to invoke emergency powers.

According to evidence presented in court, guard members and Marines supported federal immigration raids by creating perimeters, directing traffic, and securing sites. They were also present during operations at marijuana farms and accompanied federal agents during enforcement actions across Southern California. Breyer wrote that these activities were indistinguishable from policing and went beyond the protection of federal property.

The ruling grants California’s request for an injunction, preventing the Department of Defense and the Secretary of Defense from directing guard members in the state to carry out arrests, searches, or riot control unless Congress provides a valid exception. The injunction does not require the immediate withdrawal of the 300 guard members still in Los Angeles but limits their activities to roles consistent with federal law.

Breyer stayed the injunction until September 12 to allow the administration time to appeal.