Supreme Court Poised to Rule on ‘Election Day’ Mail-In Ballot Case

A closely watched case now before the U.S. Supreme Court could have major implications for election administration across the country, including in California and more than a dozen other states that continue counting certain mail ballots after Election Day.

The case, Watson v. Republican National Committee, centers on whether federal law permits states to count ballots that arrive after Election Day if they were mailed on or before Election Day.

The justices heard oral arguments in March and are expected to issue a decision before the end of the Court’s current term this month.

At issue is a Mississippi law that allows absentee ballots to be counted if they are postmarked by Election Day and received within five business days afterward.

Republican challengers argue that the law conflicts with federal statutes establishing a uniform national Election Day for presidential, U.S. Senate, and U.S. House elections.

Their position is straightforward: federal law sets a single Election Day, meaning ballots must be received by then to be counted.

Mississippi officials argue that states retain broad authority over election administration and that ballots cast by Election Day should still be valid if they arrive shortly afterward.

The dispute began after Mississippi enacted House Bill 1521 in 2020 during the COVID-19 pandemic. The law created a five-day grace period for absentee ballots arriving after Election Day.

In 2024, the Republican National Committee and other plaintiffs challenged the law in federal court.

While a federal district court initially upheld Mississippi’s policy, the U.S. Court of Appeals for the Fifth Circuit later ruled that federal election law preempts the state’s post-Election Day ballot receipt window.

Mississippi appealed to the Supreme Court, which agreed to hear the case last year.

The stakes extend far beyond Mississippi.

According to election law data, roughly 15 states and the District of Columbia currently allow at least some ballots to arrive after Election Day and still be counted, provided they meet postmark requirements.

That includes California, where mail ballots can be counted if they are postmarked by Election Day and received within the state’s statutory deadline of seven days afterward.

A ruling for the challengers could force states to require receipt of ballots by Election Day for all federal elections.

Supporters of that approach argue it would create a clearer and more uniform national standard while reducing prolonged ballot-counting periods that can leave election outcomes unresolved for days or even weeks.

Critics argue that such a ruling could disenfranchise voters who mail ballots on time but experience postal delays outside their control.