The Justice Department has sued California and asked a federal court to make the state segregate ballots from about 20,000 registered voters that federal officials call "likely noncitizens." On October 19, Acting Deputy Attorney General Trent McCotter announced charges against 28 green-card holders, all on that list, and acknowledged it may include some citizens. In an October 20 filing, state Attorney General Rob Bonta called the suit "a reckless political stunt." Los Angeles County officials reviewed a sample of 200 names; of those with a reported birthplace, 38.9% indicated they were born in the U.S., NPR reports.

Separately, on October 21 U.S. District Judge Araceli Martínez-Olguín barred Homeland Security officers in nine states from field operations aimed at people they know or should suspect are citizens, or based only on USCIS data matches, writing that the effort likely violates the Voting Rights Act's ban on voter intimidation. DHS said it has "no plans to question or investigate people we believe to be U.S. citizens." The order runs through election night unless it is appealed.