A U.S. District Court judge on Wednesday rejected an emergency request from the Justice Department to set aside mail-in ballots associated with more than 20,000 registered voters whose citizenship the Trump administration had questioned. U.S. District Judge David O. Carter ruled that the Justice Department's late attempt to intervene would disrupt an election already underway and also questioned the reliability of the government's evidence.

Department of Justice officials had identified the over 20,000 voters as "likely aliens" after Homeland Security Investigations and federal partners used data-enrichment and verification methods to flag potential non-citizens on California's voter rolls. California officials contested the list's accuracy, stating that a preliminary review had identified U.S.-born individuals and voters with no voting history among those flagged.

Carter, a Clinton appointee, determined that the Justice Department's request violated constitutional and federal-law constraints. Bill Essayli, First Assistant United States Attorney, stated that the department would file an immediate appeal with the Ninth Circuit Court of Appeals.

The Justice Department has faced several setbacks in election-related cases leading up to the midterm elections. California election officials argued that complying with the DOJ's request would be practically impossible, as county election offices had already processed over 500,000 ballots, separating them from identifying information.

Carter cautioned that the requested intervention would "wreak havoc and disrupt the election that is already underway," while adding that federal authorities could still pursue individual voting fraud cases. The governor's office did not respond to requests for comment.

Election law experts offered divided opinions on the matter. Hans von Spakovsky, an election expert at Advancing American Freedom, criticized California for not complying with the DOJ's request, citing the state's automatic voter registration system. Conversely, Rick Hasen, an election-law professor at the University of California, Los Angeles, called the DOJ's request "a total overreach of federal power."