US judge blocks Trump administration's use of troops in LA

The deployment inflamed tensions in the city and drew condemnation from Democrats, who said Trump was using the military to stifle opposition to his hardline immigration policies.

The case raised novel legal questions about presidential authority.

The lawsuit by Newsom, a prominent Democrat, alleged the troops violated long-standing U.S. norms and a law known as the Possse Comitatus Act, which sharply limits the use of federal troops for domestic enforcement.

The Trump administration countered that the U.S. Constitution permits presidents to use troops to protect federal personnel and property as an exception to the Posse Comitatus Act.

In June, Breyer found that Trump's deployment of the California National Guard was likely illegal and ordered the troops be returned to Newsom's control. That was reversed by the 9th U.S. Circuit Court of Appeals a week later.

The three-day trial that ended August 13 addressed the actions of the military after they were deployed to assist federal officers and immigration agents.

Lawyers from the California attorney general's office tried to show that the troops had performed police functions -- including setting up security perimeters and detaining two people -- and were not needed in the first place. They warned that a ruling for the Trump administration would "usher in a vast and unprecedented shift in the role of the military in our society."

The administration's lawyers tried to show that the troops only acted to protect federal agents from perceived threats and stayed within their legal limits.

Breyer appeared concerned that there were few limits on military leaders' discretion for deciding when protection was needed.

The administration still had several hundred soldiers in Los Angeles when the trial took place, although the protests had long died down. The troops were being used for security during raids on marijuana farms outside the city and as a show of force to deter protests at a popular park during an operation by immigration agents, according to evidence shown at trial.

Trump has separately sent the National Guard to patrol Washington, D.C., a city he said was ridden with crime. Breyer's decision is unlikely to impact the situation there because the president has more leeway to use the National Guard in Washington than he does in states.