Protesters being arrested are pictured in Los Angeles, the United States, June 11, 2025. Nearly 400 people in immigration protests have been arrested or detained by the Los Angeles Police Department since Saturday, media reports said. [Photo/Xinhua]

The U.S. Justice Department on Monday sued the City of Los Angeles, Mayor Karen Bass, and the City Council, asking a federal judge to strike down the city's "sanctuary" ordinance on the grounds it obstructs federal immigration enforcement.

Filed in the U.S. District Court for the Central District of California, the lawsuit argued that Los Angeles violated the Constitution's Supremacy Clause and two federal information -- sharing statutes by forbidding local police and other agencies from cooperating with U.S. Immigration and Customs Enforcement (ICE) unless a suspect faces serious felony charges.

The Justice Department sought a court order blocking the ordinance, which took effect on Dec. 9, 2024, after a unanimous council vote.

U.S. Attorney General Pamela Bondi said the policy was "the driving cause of the violence, chaos, and attacks on law enforcement that Americans recently witnessed in Los Angeles," according to a press statement issued Monday. She called the suit part of President Donald Trump's pledge to "end lawless sanctuary jurisdictions."

Los Angeles officials sharply disputed that narrative. "To characterize what is going on in our city as a city of mayhem is just an outright lie," Bass told the Los Angeles Times on June 12 while visiting demonstrators denouncing recent immigration raids. The mayor argued that federal swoops "terrorize families and harm our economy."

The ordinance barred city funds, staff, or property from aiding federal immigration tasks, blocked most data sharing with ICE, and directed city jails to ignore detainer requests unless a judicial warrant is produced.

City leaders said the measure codified limits already imposed by California's 2017 Values Act, which survived a 2019 challenge at the Ninth U.S. Circuit Court of Appeals. According to U.S. Census Bureau estimates, about 35 percent of Los Angeles County residents are foreign born.

California's top officials quickly rallied behind the nation's second largest city. Governor Gavin Newsom branded the lawsuit "political theater" in a written statement.

State Attorney General Rob Bonta told a Monday news conference that federal officers "cannot conscript local law enforcement to do their job," citing the Supreme Court's anti-commandeering doctrine.

Civil rights advocates echoed that view. The American Civil Liberties Union of Southern California called the suit "an unconstitutional attack on immigrant communities" in an emailed statement, arguing that sanctuary rules encouraged crime victims and witnesses to speak with police.

The Coalition for Humane Immigrant Rights of Los Angeles warned that rolling back protections would "drive thousands of Angelenos deeper into the shadows," according to its Monday press release.

Conservative organizations applauded the filing. The Center for Immigration Studies said the ordinance "releases deportable offenders back onto the streets." At the same time, the Federation for American Immigration Reform called it "a long overdue step toward public safety" in separate policy briefs.

Legal analysts said the clash could reshape the balance of power between the federal government and local jurisdictions. Courts have historically been reluctant to force cities to enforce deportations. Yet, the Justice Department argued Los Angeles went further than prior cases by forbidding even contractors from sharing basic inmate release information.

If the Trump government prevails, Los Angeles could be compelled to grant ICE routine access to city jails, notify agents when non-citizen inmates are released, and honor immigration detainers, which critics contended would erode years of trust building with immigrant communities.

Should the city win, analysts expected other U.S. municipalities to strengthen comparable protections, creating an even wider patchwork of approaches nationwide.

The suit is the latest in a string of federal challenges filed this year against sanctuary measures in New York, Chicago, and several New Jersey cities.