In a surprise victory for voting rights, the Supreme Court on Monday upheld a Mississippi law allowing mail-in ballots to be counted up to five days after Election Day, as long as they had been postmarked by the day of the election.

The 5-4 decision by Justice Amy Coney Barrett, which was joined by Chief Justice John Roberts and the court’s three liberal justices, averts a major election disaster that would have injected chaos into the midterms. Fourteen states have mail-in ballot grace periods on the books, and 30 states accept ballots from overseas and military voters sent before or on Election Day but only received after. The New York Times found that during the 2024 election “at least 725,000 ballots were postmarked by Election Day and arrived within the legally accepted post-election window.” Changing mail-in ballot deadlines months before the general election could have disenfranchised hundreds of thousands of voters who could have been unaware of the stricter rules, or have their ballots thrown out because of postal delays, or because they live in remote, rural locations in states like Alaska.