Federal Judge Restricts Warrantless Immigration Arrests in Southern California

A federal judge has issued an order blocking immigration officers from making warrantless arrests in Southern California unless they determine the person is likely to escape. The preliminary injunction, granted Sept. 2 and unsealed Wednesday by U.S. District Judge Maame Ewusi-Mensah Frimpong, requires the government to consider the “totality of the circumstances known to the agent or officer” regarding a person's likelihood of escape before making a civil immigration arrest without a warrant.

The lawsuit was filed last fall by the American Civil Liberties Union of Southern California, Public Counsel, and Los Angeles immigrant advocacy groups amid a surge in immigration enforcement in the region. The order applies to the Central District of California, encompassing Los Angeles, Orange, Riverside, San Bernardino, Ventura, Santa Barbara, and San Luis Obispo counties.

Frimpong also ordered the government to thoroughly document the probable cause leading to an arrest before a warrant could be obtained, stating that the mere fact of being in the country illegally is insufficient grounds for a warrantless arrest. "Without this, Defendants cannot show that any arrest was proper," Frimpong wrote, denying the government's request to delay the order to allow time for an appeal.

The U.S. Department of Homeland Security did not immediately respond to a request for comment.

The lawsuit also sought to prohibit roving patrols from making stops and arrests based solely on race, language, or occupation, and to protect the right to counsel for detainees. Frimpong had previously issued a temporary restraining order to restrict these broad immigration operations, but it was lifted by the U.S. Supreme Court in September. At that time, Justice Brett Kavanaugh suggested that apparent ethnicity could be a relevant factor for a stop if combined with other information.

The unsealed preliminary injunction followed a hearing where Frimpong signaled her inclination to side with the plaintiffs in a tentative ruling. Federal judges in Portland, Colorado, Washington D.C., and the Eastern District of California have previously issued similar injunctions against warrantless arrest practices.

Plaintiffs argued that in many tracked arrests in Southern California, officers failed to document the likelihood of escape. Federal attorney Daniel Mummolo countered that there is no statutory requirement to document such assessments and cited a January 2026 memo from former acting director of U.S. Immigration and Customs Enforcement Todd Lyons that allowed officers to make “on-the-spot” escape risk determinations. Frimpong questioned this, stating, "You have not presented evidence of officers saying, ‘Yeah I didn’t write it down but I did do it.'"

Plaintiffs' attorney Laura Perry Stone clarified that the memo requires officers to determine both that the person is likely to leave the location and is unlikely to be found at another identifiable location. Frimpong's order cited “a wealth of record evidence,” including government directives, arrest narratives, agent depositions, and video evidence, suggesting the government's policy and practice involved escape risk assessments based solely on unlawful status, "false assertions," or no assessment at all. The judge noted one instance where video contradicted an agent's claim that an individual was "running away," showing the person walking and texting before being approached.

"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.”