On Tuesday, California Gov. Gavin Newsom celebrated a court ruling that declared the deployment of the National Guard in Los Angeles illegal, calling it a victory against U.S. President Donald Trump and reminding him that “No President is King.”

Earlier, California had clashed with the White House in a legal battle over the mobilization of more than 4,000 California National Guard soldiers in June without the governor’s consent — the first such case in the United States in 60 years.

U.S. District Judge Charles Breyer in San Francisco ruled that Trump’s order constituted a clear violation of the 1878 Posse Comitatus Act, which prohibits the use of U.S. military forces for domestic law enforcement.

“Yet there was no rebellion, nor was civilian law enforcement unable to respond to the protests and enforce the law,” Breyer said in his ruling, as reported by USA Today.

“The evidence at trial established that defendants systematically used armed soldiers (whose identity was often obscured by protective armor) and military vehicles to set up protective perimeters and traffic blockades, engage in crowd control, and otherwise demonstrate a military presence in and around Los Angeles. In short, defendants violated the Posse Comitatus Act,” he added.

“Today, the court ruled in favor of democracy and the Constitution. No president is king, not even Trump, and no president can trample a state’s power to protect its people,” Newsom said, recalling that he had been warning that the Republican president was breaking the law by creating “a national police force” with himself as its chief.

Trump had ordered the deployment to contain protests against immigration raids, arguing that local authorities could not handle the situation, despite Los Angeles police having dispersed the demonstrators.

California Attorney General Rob Bonta said Trump had engaged in “political theater” for more than two months by using National Guard troops and about 300 Marines “as pawns” to advance his anti-immigrant agenda.

The ruling represents a major victory for Newsom, who has emerged as the most prominent Democratic figure opposing the U.S. president, and comes amid speculation over the potential deployment of troops to Chicago, another Democratic stronghold.

The court order could prevent the White House from following through on threats to send troops to Illinois’ largest city, as it already did in the nation’s capital, under the pretext of combating high crime rates.