Supreme Court Upholds Mail Ballots Postmarked by Election Day, 5-4.

The Supreme Court ruled 5-4 on June 29, 2026, that states may count mail ballots that are postmarked by Election Day even if they arrive a few days later. Justice Amy Coney Barrett wrote the majority opinion, and Chief Justice John Roberts joined her and the court’s three liberals, NPR reported. The ruling rejected a Republican National Committee challenge and preserved mail ballot grace periods in 18 states and territories.

Related coverage: The same fight runs through other channels. The Postal Service floated a rule to share voters’ mail-ballot lists with the government, and Ohio lawmakers tried to bolt a new ID requirement onto mail-in voting.

What the Court Decided

The case, Watson v. RNC, tested a Mississippi law that counts mail ballots as long as they are postmarked by Election Day and arrive within five business days. Republicans argued the grace period conflicts with the federal law that sets a single national Election Day.

The court disagreed. The majority held that a voter casts a ballot when they mail it, so a ballot postmarked by Election Day is cast on time even if it is delivered later. Barrett wrote the opinion. Justices Thomas, Alito, Gorsuch, and Kavanaugh dissented.

A Surprise, and a Loss for the RNC

The outcome was not the one most observers expected. At argument in March, the justices sounded ready to strike the Mississippi law down. The final ruling went the other way.

It is a direct loss for the Republican Party, which brought the case, and for President Trump, who has spent years attacking mail voting as fraudulent. No court has found that grace periods cause fraud. They exist so that a ballot mailed on time is not thrown out because the post office was slow.

What It Means for Voters

The ruling keeps the rules in place for the November midterms. Mississippi and 13 other states, plus several territories, count ballots postmarked by Election Day that arrive in the days after.

The voters who benefit most are the ones with the least control over the mail. Military families stationed overseas, rural voters far from a post office, and anyone whose ballot sits in a delayed mail stream now keep the protection. Had the case gone the other way, on-time ballots in 18 states could have been tossed for arriving a day late.

Why It Matters

This was a 5-4 decision. One vote separated a win for mail voting from a ruling that could have invalidated millions of on-time ballots before a high-stakes election. Barrett and Roberts crossing over is what made the difference.

The protection is real but not permanent. The grace periods are state laws, and a state legislature can repeal them. The same coalition that brought this case can bring another. A durable fix would put the rule in federal law, so the right to have an on-time ballot counted does not depend on the state you live in or the makeup of the next court.

What You Can Do Now

Use the letter below to ask your members of Congress to codify mail ballot protections nationwide through the Freedom to Vote Act, so an on-time ballot counts in every state.
Know your state’s mail ballot deadline and use it. If you vote by mail, send your ballot as early as you can, and check whether your state counts ballots postmarked by Election Day. Find your rules at vote.gov.
Call your senators and representative at (202) 224-3121. Tell them you want on-time mail ballots protected in federal law, not left to a one-vote majority on the Supreme Court.