A high-stakes trial began Monday in a California courtroom over whether the Trump administration violated federal law when it deployed thousands of National Guard troops and United States Marines to Los Angeles following protests over immigration raids in June.

Gov. Gavin Newsom alleges the Trump administration broke a 19th Century law called the Posse Comitatus Act when it deployed military units to Los Angeles in June.

A federal judge in San Francisco will hear arguments on whether military troops deployed this summer by the Trump administration to Los Angeles violated a federal law that bars troops from conducting law enforcement duties within the country.