Trial to start on whether deployment of National Guard to Los Angeles violated federal law

California is asking Judge Charles Breyer in San Francisco to order the Trump administration to return control of the remaining troops to the state and to stop the federal government from using military troops in California "to execute or assist in the execution of federal law or any civilian law enforcement functions by any federal agent or officer."

The 1878 Posse Comitatus Act prevents the president from using the military as a domestic police force. The case could set precedent for how Trump can deploy the guard in the future in California or other states.

On Monday, Trump said he was deploying the National Guard across Washington, D.C., and taking over the city's police department in the hopes of reducing crime, even as the mayor has noted that crime is falling in the nation's capital.

In June, the Department of Defense ordered the deployment of roughly 4,000 California National Guard troops and 700 Marines to Los Angeles. Most of the troops have since left but 250 National Guard members remain, according to the latest figures provided by the Pentagon. The remaining troops are at the Joint Forces Training Base, in Los Alamitos, according to Newsom.

Newsom won an early victory from Breyer, who found the Trump administration violated the Constitution's 10th Amendment, which defines power between federal and state governments, and exceeded its authority.

The Trump administration immediately appealed, arguing that courts can't second guess the president's decisions and secured a temporary halt allowing control of the California National Guard to stay in federal hands as the lawsuit unfolds.

After their deployment, the guard members accompanied federal immigration officers on raids in Los Angeles and at two marijuana farm sites in Ventura County while Marines mostly stood guard around a federal building in downtown Los Angeles that includes a detention center at the core of protests.

The Trump administration argued the troops were needed to protect federal buildings and personnel in Los Angeles, which has been a key location in the federal government's aggressive immigration strategy.

Since June, federal agents have rounded up immigrants without legal status to be in the U.S. from Home Depots, car washes, bus stops, and farms. Some U.S. citizens have also been detained.

Ernesto Santacruz Jr., the field office director for the Department of Homeland Security in Los Angeles, said in court documents that the troops were needed because local law enforcement was slow to respond when a crowd gathered outside the federal building to protest the June 7 immigration arrests.

"The presence of the National Guard and Marines has played an essential role in protecting federal property and personnel from the violent mobs," Santacruz said.

After opposition from the Trump administration, Breyer issued an order allowing California's attorneys to take Santacruz's deposition. They also took a declaration from a military official on the troops' role in Los Angeles.

The Trump administration's attorneys argued in court filings last week that the case should be canceled. They argued that the president has the authority to call on the National Guard to enforce U.S. laws when federal law enforcement isn't enough.

Trump federalized members of the California National Guard under Section 12406 of Title 10, which allows the president to call the National Guard into federal service when the country "is invaded," when "there is a rebellion or danger of a rebellion against the authority of the Government," or when the president is otherwise unable "to execute the laws of the United States."

Breyer found the protests in Los Angeles "fall far short of 'rebellion.'"

"Next week's trial is not cancelled," he said in a ruling ordering the three-day bench trial.