A federal judge has ruled that the Trump administration’s deployment of National Guard troops to Los Angeles during immigration enforcement protests violated federal law. Judge Charles Breyer issued the ruling on Tuesday, declaring that the administration’s use of troops amounted to a breach of the Posse Comitatus Act, an 1878 law that prohibits the use of federal military forces in civilian law enforcement.

“This was intentional. Defendants instigated a months-long deployment of the National Guard and Marines to Los Angeles for the purpose of establishing a military presence there and enforcing federal law. Such conduct is a serious violation of the Posse Comitatus Act,” Breyer wrote in his decision.

The ruling stems from a lawsuit filed by California, which argued that the deployment violated legal restrictions on military involvement in domestic law enforcement. Federal lawyers for the Trump administration countered that the troops were mobilized under presidential authority to protect federal officers, not to enforce laws directly, and therefore fell outside the scope of the Posse Comitatus Act.

Judge Breyer, who was appointed by former president Bill Clinton, rejected that argument. However, he paused the order until Friday to allow the administration an opportunity to appeal before it takes effect.

The deployment of 2,000 National Guard troops to Los Angeles was ordered by Donald Trump in June after two days of clashes between demonstrators and United States immigration authorities. State and local officials, including California Governor Gavin Newsom, objected strongly to the move, calling it an abuse of presidential power.

The decision marked the first time since the 1992 Los Angeles riots, following the acquittal of four police officers in the beating of Rodney King, that a U.S. president used such authority to federalize guard troops in the city. Unlike in 1992, there was no widespread unrest in Los Angeles at the time of Trump’s decision.

The ruling comes as the Trump administration continues its immigration crackdown, which has included expanding federal law enforcement operations in Democrat-led cities. Trump has discussed potential future deployments of National Guard troops to Chicago, Baltimore, and New York.

In a separate move on August 11, Trump ordered more than 2,200 soldiers from states including Mississippi and Louisiana to Washington, D.C., after declaring a “crime emergency” in the capital. That action also saw the U.S. Department of Transportation assume control of Union Station from Amtrak, citing safety and infrastructure concerns.