The Justice Department was met with skepticism from a federal judge this week during a multiday trial over the legality of President Donald Trump’s deployment of the National Guard to Los Angeles in June.

The trial centered on whether the president’s deployment of troops to protect federal property and officials after unrest over immigration operations violated the Posse Comitatus Act, which prohibits troops from being used for regular law enforcement activities. Judge Charles Breyer of the U.S. District Court for the Northern District of California heard arguments during a three-day trial in a San Francisco courtroom.