The U.S. Supreme Court on Monday rejected an emergency appeal from the Trump administration seeking to segregate more than 20,000 California mail-in ballots that were flagged as potentially cast by noncitizens. Justice Elena Kagan denied the request without comment, a decision made just before the midterm elections.

The administration argued that segregating the ballots would preserve them for investigation without canceling any votes, stating that once illegally cast ballots are counted and commingled, the harm is irreparable. However, California officials disputed the federal government's claims about the ballots and raised concerns that the federal list might contain errors, potentially disenfranchising eligible voters.

Lower courts, including the 9th U.S. Circuit Court of Appeals, had previously rejected the administration's request. Judges cited California's authority over election procedures and warned that granting the request could jeopardize the election. A federal judge in Washington, D.C., also issued an injunction, stating that the administration had likely violated the Constitution by attempting to overstep state and congressional election responsibilities.

The dispute originated from a Department of Justice lawsuit filed on October 15, alleging that California was hindering enforcement of federal law prohibiting noncitizens from voting in federal elections. The DOJ contended that the state violated the Supremacy Clause of the Constitution. This action was part of a broader effort by the administration to influence state election practices, including demands for voter roll access and warnings about prosecuting officials for allowing noncitizens to vote.