A federal judge has issued a preliminary injunction restricting immigration authorities from carrying out warrantless arrests in Southern California unless officers establish that a suspect poses an immediate flight risk.
The decision, handed down on September 2 and unsealed Wednesday by U.S. District Judge Maame Ewusi-Mensah Frimpong, requires agents to evaluate the full scope of available facts before detaining individuals without a warrant.
The mandate covers the Central District of California, spanning Los Angeles, Orange, Riverside, San Bernardino, Ventura, Santa Barbara, and San Luis Obispo counties.
Under the ruling, immigration officials must record detailed documentation establishing probable cause and flight risk prior to an arrest. Judge Frimpong noted that an individual’s unlawful status alone does not satisfy the legal threshold for a warrantless detention.
“Without this, Defendants cannot show that any arrest was proper,” Frimpong wrote, denying a federal request to pause the order pending appeal.
The Department of Homeland Security has not issued an official response.
The lawsuit was initiated last year by the ACLU of Southern California, Public Counsel, and local advocacy groups during an uptick in regional enforcement. Plaintiffs submitted evidence indicating agents regularly omitted flight-risk evaluations.
During court proceedings, government counsel defended current protocols, pointing to a January 2026 internal memorandum issued by former acting ICE Director Todd Lyons that permitted officers to evaluate escape risks on the spot.
“There’s no statutory requirement to document,” argued federal attorney Daniel Mummolo.
“You have not presented evidence of officers saying, ‘Yeah I didn’t write it down but I did do it,’ ” Judge Frimpong countered during the hearing.
In her final ruling, Frimpong concluded that video records, agent testimony, and internal narratives showed a systemic failure to conduct proper escape assessments, noting one case where agents claimed a suspect fled, despite video showing him walking normally while using his phone.
“This court order should put an end to hundreds – if not more – of unlawful arrests that continue throughout Southern California,” said Mayra Joachin, an attorney with the ACLU of Southern California. “We will closely monitor compliance with this court order, and expect the federal government to abide by it.”
Similar rulings limiting warrantless civil immigration arrests have previously been enacted by federal courts in Oregon, Colorado, Washington, D.C., and Northern California.