An official Pennsylvania mail-in ballot. Associated Press File Photo

HARRISBURG — Pennsylvania's highest court on Wednesday said people whose mail ballots are rejected for not following technical procedures in state law can cast provisional ballots, a decision sure to affect some of the thousands of mail-in votes likely to be rejected this fall.

The Supreme Court ruled 4-3 that Butler County's Republican-majority election board must count provisional ballots that were cast by two voters in the primary after they learned their mail-in ballots were voided because they arrived without mandatory secrecy envelopes.

The decision was a legal defeat for the Republican National Committee and the state Republican Party, which had argued Butler County had correctly rejected the provisional ballots cast during the April primary.

Secrecy envelopes keep ballots concealed as elections workers open the stamped outer envelopes used to mail the whole packets back. Voters also must sign and date the exterior envelopes. Pennsylvania voters have so far applied for more than 1.9 million mail ballots.

The two voters had received emails notifying them of the “naked ballot” problem, and they both went to their polling places on the primary election day and cast provisional ballots. They sued after learning the Butler County Board of Elections also rejected their provisional ballots, and a county judge upheld the election officials’ decisions.

Mail-in ballot rules in Pennsylvania changed drastically under a 2019 law, widely expanding their use and producing a series of lawsuits. Pennsylvania’s status as the swing state with the most electoral votes in the close presidential election, now in its final two weeks, puts the court decision under heightened scrutiny as the parties scrape for votes.

Most counties — but not all — help inform voters in advance of Election Day that their mail-in ballot will be rejected, giving them the opportunity to cast a provisional ballot at their polling place, according to the American Civil Liberties Union of Pennsylvania.

“The General Assembly wrote the Election Code with the purpose of enabling citizens to exercise their right to vote, not for the purpose of creating obstacles to voting,” wrote Justice Christine Donohue for the majority.

In a dissent joined by the other Republican on the court and one of the five Democratic justices, Justice Kevin Brobson argued the two voters had already cast their ballots by mail, so the provisional ballots they also cast should not be counted.

He said voters have to follow election laws, whether that means using the secrecy envelope or showing up at the polls during the time they are open. State lawmakers could have told election boards to count provisional ballots under such circumstances, Brobson wrote.

“The General Assembly, however, clearly did not, and this Court is not at liberty to make additions or modifications to the unambiguous statutory language in order to effectuate that result,” Brobson said.

An ACLU lawyer involved in the case, Witold Walczak, said Wednesday the decision applies across the state, that all voters whose mail-in ballots are disqualified for any reason will be allowed to cast valid provisional ballots.

“In the end, this is about not two votes counting or zero votes counting, it’s about one vote counting,” Walczak said. “If your first vote does not count, as with these disqualified mail ballots, the provisional ballot must count. You’re entitled to have one vote counted.”

Walczak expects the number of disqualified mail-in ballots to be in the tens of thousands in this year’s election.