The U.S. Supreme Court on Friday unanimously rejected a Republican request to bar Pennsylvania voters who sent in defective mail-in ballots from casting provisional ballots at the polls on Election Day, a decision seen as a victory for Democrats in the battle state.

But in rejecting the last-minute appeal by the Republican National Committee and the Pennsylvania Republican Party, three of the court’s Republican justices – Samuel A. Alito Jr., Clarence Thomas and Neil Gorsuch – described the issue as “a matter of considerable importance.” ”. and appeared to leave the door open to future litigation after the election.

At stake was a 4-3 decision last week by the Pennsylvania Supreme Court that allowed voters whose mail-in ballots had been rejected for procedural errors, such as missing dates or failing to use a required security envelope. , continue voting at the polls.

The case arose in Butler County, which had a policy of rejecting those provisional votes. It was part of a broader series of litigation that has shaped which votes will be counted in Pennsylvania’s election.

Separately on Friday, the Pennsylvania Supreme Court blocked a lower court ruling That injected confusion into the debate over whether election officials should count undated mail-in ballots. Instead, he doubled down on an earlier decision on the issue that this year, at least, they shouldn’t.

Tens of thousands of ballots are rejected every election because of these voter errors. And in a state like Pennsylvania, where this year’s presidential race will likely be incredibly narrow, the fate of voters’ ability to cast a provisional ballot if they make a mistake could ultimately become significant.

Democrats are much more likely to vote by mail than Republicans.

Republicans, in their appeal of the Butler County case, accused the state’s highest court of rewriting election law. They urged U.S. Supreme Court justices to void any provisional votes cast by voters whose mail-in ballots had previously been rejected until new litigation could be resolved.

Democrats and voting rights groups argued that suspending the ruling would only cause confusion, create problems for election administrators and, worse, potentially disenfranchise thousands of otherwise eligible voters.

Although the U.S. Supreme Court justices ultimately decided to let the state court ruling stand, Alito and his Republican colleagues expressed some interest in weighing in on the issue in the future. But they described the current case as an inadequate vehicle for that debate.

“Because the only partisan state election officials in this case are members of a small county election board,” they wrote, “we cannot order other election boards to sequester affected ballots.”

In a statement after the ruling, RNC spokesperson Claire Zunk touted the party’s victories in other cases in Pennsylvania. including a ruling forcing Bucks County to extend on-demand mail-in voting for three days.

“While we are disappointed by the Supreme Court’s ruling, this week we have achieved three important victories for election integrity in Pennsylvania,” he said.

But Witold Walczak, legal director of the ACLU of Pennsylvania, which advocated for the inclusion of provisional ballots, hailed it as a victory for voting rights.

“A small error that is irrelevant to a person’s eligibility to vote should never interfere with the vote count, and provisional votes are a safety mechanism that has been around for decades — a backup for voters,” he said. “We are grateful that the RNC’s argument failed and that voters can rely on provisional ballots as a way to ensure their vote counts.”