Supreme Court to Review Late Mail Ballot Rules

The Supreme Court on Monday agreed to hear a case that could determine whether states may count mail ballots arriving after Election Day, provided they are postmarked by that date, a practice followed in numerous states for federal elections.

The justices took up an appeal from Mississippi, where a federal appeals court last year struck down the state's law allowing such ballots to be counted up to five days after Election Day. The U.S. Court of Appeals for the 5th Circuit ruled that the state provision conflicts with federal law, which establishes a uniform Election Day for congressional and presidential races. The panel's decision reversed an earlier ruling by a federal district judge who found no such conflict.

Mississippi's law, challenged by the Republican National Committee, the Mississippi Republican Party, the Libertarian Party of Mississippi and a state voter, permits election officials to accept and tally mail ballots postmarked on or before Election Day but received shortly afterward. The state argues that the appeals court decision threatens to create widespread uncertainty in elections nationwide. In filings to the Supreme Court, Mississippi Attorney General Lynn...