What is an election and when is it completed?

That’s the legal question at the heart of Watson v. Republican National Committee, the mail-in ballot case the U.S. Supreme Court took up in November 2025. The court will most likely hand down a ruling before the midterm elections in 2026.

Mississippi law, similar to that of 15 other states, allows for mail-in ballots postmarked by Election Day to be received by election officials up to five days later, then counted.

But the Republican National Committee is arguing in the Watson case, which was brought against the state of Mississippi in January 2024, that this procedure is not legal. An election, the argument goes, includes the receipt of ballots; therefore, all ballots must be in hand at the close of Election Day – the congressionally established “Tuesday after the first Monday” in November.

President Donald Trump’s March 2025 executive order 14248 similarly calls for ballots to be received no later than Election Day if they are to be counted, saying that doing otherwise “is like allowing persons who arrive 3 days after Election Day, perhaps after a winner has been declared, to vote in person at a former voting precinct, which would be absurd.”

The Supreme Court’s decision on mail-in ballots could have major consequences for the 47.6 million Americans who voted by mail in 2024, as well as more than 900,000 overseas military and civilian voters covered under the Uniformed and Overseas Citizens Absentee Voting Act. More than 28 million of the 47.6 million domestic mail-in votes and nearly 800,000 of the 900,000 votes cast and counted under the uniformed and overseas citizens act were from states that allow for return of mail-in ballots after Election Day.

As a political scientist and scholar of migration, I have conducted research for over 20 years on military service members and civilian U.S. citizens living overseas.

Currently, 16 states plus the District of Columbia allow domestic absentee ballots that are postmarked by Election Day to be counted if they arrive after Election Day;

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