Americans have had their mail-in ballots counted after Election Day for generations − a Supreme Court ruling could end the practice

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 rrder 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; 29 states extend that right to military and civilian voters living overseas, recognizing that international mail often delays ballot return.

According to the U.S Constitution, states administer elections. Under the equal protection clause, however, the federal government can pass legislation to prevent inequalities in access to voting. This includes facilitating the right to vote of military service members and civilian U.S. citizens living overseas.

The Supreme Court will decide whether federal law overrides state election administration in determining whether ballots that are postmarked by Election Day but arrive later can be counted.

A 250-year history

The history of absentee, or mail-in, ballots in U.S. elections stretches back 2½ centuries.

Soldiers first voted by mail during the American Revolution, when men from the town of Hollis, New Hampshire, wrote their town leaders asking to have votes counted in local elections.

Pennsylvania passed the first law allowing soldiers to vote absentee in the War of 1812, a right expanded in the Civil War when 19 Union and seven Confederate states allowed soldiers to vote absentee.

Absentee voting for soldiers from all states was codified in federal law in 1942. A 1944 amendment specified that ballots that were postmarked by Election Day and arrived within two weeks after Election Day could be counted.

Some civilians residing overseas, including civilian government employees and spouses and dependents of military and civilian employees, gained absentee ballot voting rights with the 1955 Federal Voting Assistance Act. All overseas U.S. citizens were enfranchised with the 1975 Overseas Citizens Voting Act. The 1986 Uniformed and Overseas Citizens Absentee Voting Act consolidated military and civilian voting rules. Later laws addressed electronic communications.

Over 1,000 military service members requested an absentee ballot in Mississippi’s 2024 election, along with nearly 1,000 civilian overseas voters. Nationally, more than 900,000 people voted in 2024 under the uniformed and overseas citizens act.

Many of these U.S. citizens would be affected by a ballot receipt deadline on Election Day. Their votes, coming from around the world, are often not able to be counted because of late arrival.

Under the magnifying glass in Florida

Overseas absentee military and civilian ballots came to widespread notice in Florida in the 2000 presidential election. That election – and ultimately the presidency — centered on state election law being waived by canvassing boards under pressure from the Republican Party to count military and civilian absentee ballots received after Election Day.

The Supreme Court decided in December 2000 to stop further counting of mail-in ballots received after Election Day because of tight certification deadlines, with the Electoral College meeting just six days later.

Congress was concerned about the unequal treatment of ballots at home and abroad in the 2000 election. To move toward addressing these concerns, Congress passed the Help America Vote Act in 2002, which includes measures to facilitate overseas voting.

Ensuring that everyone gets a vote

Increasing mail-in voting has been a question of making sure everyone who qualifies to vote can do so. Oregon was the first state, in 1998, to offer mail-in voting. Surveys have shown that more Democrats than Republicans voted by mail in 2020. Sending ballots to all voters reduces that gap.

By 2020, 33 states offered “no excuse” domestic absentee voting, with others expanding or facilitating mail-in voting during the COVID-19 pandemic that year.

The Federal Voting Assistance Program is charged with making it easier for overseas voters to vote. It continues to find obstacles, including problems in returning ballots on time. Meanwhile, Florida election supervisors in November 2025 requested that Florida officials reinstate a checkbox that was dropped from Florida absentee ballots in 2021. The checkbox allowed the voter to request an absentee ballot for the next election.

Mail-in ballot security

Following concerns about the security of mail-in ballots in the 2000 election in Florida, the 2002 Help America Vote Act required that all states have a minimum security requirement.

The multiple levels of scrutiny include signature comparison, ballot tracking and penalties for malfeasance from the moment of registration to ballot request, to ballot receipt. With these layers of security there were only an estimated four fraudulent votes cast for every 10 million mail-in ballots in the 2016, 2018, 2020 and 2022 U.S. general elections.

Mail-in voting elsewhere

The United States is one of 32 countries worldwide that allow mail-in voting for at least some of its citizens. These include the United Kingdom since 1945 and Germany since 1957.

In Germany’s federal elections in 2025, 37% of all voters, or 18.5 million citizens, cast a ballot by mail. German citizens who are eligible to vote automatically receive ballots. In the United Kingdom’s 2024 election, just under 5%, or nearly 1.3 million citizens, applied for mail-in ballots.

The bottom line

The Supreme Court case could reshape the voting landscape in the United States, potentially affecting 47 million people, including some 5 million military and civilian voters living abroad. Watson v. Republican National Committee could also affect laws in 29 states. The outcome of the case has the potential to make voting more difficult for millions of civilian and military voters at home and abroad.