(NewsNation) — A federal judge ruled that President Donald Trump’s use of the National Guard to fight crime in California is illegal and that the deployment of federal troops violated the Posse Comitatus Act.
Judge Charles Breyer ruled the deployment violated Act, which prohibits the use of military force for domestic law enforcement without the authorization of Congress.
The ruling blocked the president from continuing to deploy troops in the state.
In an attempt to subdue protesters, Trump had deployed more than 4,000 National Guard troops and 700 active-duty U.S. Marines to Los Angeles.
The move drew swift backlash from California Gov. Gavin Newsom, who filed a lawsuit against Trump over what he called an “unlawful” deployment of federal troops to LA County.
The Trump administration argued the troops were used to protect federal personnel, which is an exception to the Posse Comitatus Act.
Breyer said in his opinion that the troops were used for crowd control, establishing perimeters and blocking traffic.
Trump cited federal code for sending troops to LA protests
In sending troops to LA, Trump cited Title 10 of the U.S. Code, which allows the president to “call into federal service members and units of the National Guard of any State in such numbers as he considers necessary” when there is a rebellion, an invasion or the danger of either happening.
“Orders for these purposes shall be issued through the governors of the States or, in the case of the District of Columbia, through the commanding general of the National Guard of the District of Columbia,” the code reads.
Newsom did not request troops in LA, and the state’s lawsuit stated that there was neither a “rebellion” nor an “invasion,” nor the possibility of either.
Trump’s federal troop deployment was the first without a governor’s request since the Civil Rights Movement — and a violation of federal code, according to California’s lawsuit.
What is the Posse Comitatus Act?
The Posse Comitatus Act is an 1878 law that forbids the U.S. military from participating in civilian law enforcement on U.S. soil.
Exceptions include enforcement approved by Congress or under circumstances that are “expressly authorized by the Constitution.”
Notably, the Posse Comitatus Act refers only to the Army and Air Force — a different statute, 10 U.S. Code 275, forbids Navy and Marine Corps members from the same thing.
According to the nonprofit Brennan Center for Justice, “members of the National Guard are rarely covered by the Posse Comitatus Act because they usually report to their state or territory’s governor.”
“However, when Guard personnel are called into federal service, or ‘federalized,’ they become part of the federal armed forces, which means they are bound by the Posse Comitatus Act until they are returned to state control,” the center said.
Essentially, the act prevents federal troops from doing anything other than supporting Immigration and Customs Enforcement and protecting government personnel and property.
But there is one notable override: the Insurrection Act.
Trump invoked the Insurrection Act for LA protests
Trump’s legal team had argued the deployment was justified under the Insurrection Act, originally enacted in 1792, which can be invoked to suppress rebellion, violence or enforce the law in certain situations.
Trump called protesters “paid insurrectionists” on social media and said demonstrators “should be in jail.”
“In theory, the Insurrection Act should be used only in a crisis that is truly beyond the capacity of civilian authorities to manage,” the Brennan Center said, adding that the law fails “to adequately define or limit when it may be used.”
The Trump administration is expected to appeal Breyer’s ruling.
NewsNation’s Steph Whiteside contributed to this story.