A U.S. federal judge has ruled that the Trump administration violated federal law by deploying National Guard troops for domestic law enforcement duties in Los Angeles, siding with a legal challenge brought by California Governor Gavin Newsom.

The case centered on the Posse Comitatus Act, a longstanding statute that prohibits the use of the U.S. military in civilian policing without explicit congressional authorization. In a 52-page opinion released Tuesday, U.S. District Judge Charles R. Breyer of the Northern District of California found that the administration had crossed a constitutional line.

“The Trump administration violated federal law with its use of National Guard troops in Los Angeles,” Breyer wrote. “National Guard troops carried out domestic law enforcement actions, violating the federal Posse Comitatus Act.”

While the court ruled the deployment unlawful, Judge Breyer’s order was narrowly framed. He clarified that the government is not required to immediately withdraw the roughly 300 National Guard troops still stationed in the city, but he did issue restrictions on their involvement in civilian policing.

“The administration was not required to pull back the 300 troops still stationed in Los Angeles,” Breyer noted. “But I am blocking them from certain actions, and I have stayed my ruling until next week.”

The ruling effectively places a temporary hold on enforcement duties while allowing the deployment to continue in a more limited capacity—at least until further legal proceedings determine next steps.

The decision marks a significant legal rebuke of the Trump administration’s handling of federal responses to domestic unrest and could set a precedent for future challenges to executive use of military forces within U.S. borders.

Governor Newsom’s office welcomed the ruling as a reaffirmation of civilian oversight and constitutional boundaries, though the administration has not yet commented on whether it will appeal.

The ruling signals that while the federal government retains the power to deploy the National Guard, its role must remain clearly defined and within the scope of federal law—particularly when it comes to operations involving civilian populations.