HARRISBURG, Pa. (AP) — A court decided Thursday that voters in the presidential battleground of Pennsylvania can cast provisional ballots in place of mail-in ballots that are rejected for a garden-variety mistake they made when they returned it.

Democrats typically outvote Republicans by mail by about 3-to-1 in Pennsylvania, and the decision by a state Commonwealth Court panel could mean that hundreds or thousands more votes are counted in November’s election, when the state is expected to play an outsized role in picking the next president.

The three-member panel ruled that nothing in state law prevented Republican-controlled Butler County from counting two voters’ provisional ballots in the April 23 primary election, even if state law is ambiguous.

A provisional ballot is typically cast at a polling place on Election Day and is separated from regular ballots in cases when elections workers need more time to determine a voter’s eligibility to vote.

The case stems from a lawsuit filed by two Butler County voters who received an automatic email before the primary election telling them that their mail-in ballots had been rejected because they hadn’t put them in a blank “secrecy” envelope that is supposed to go inside the ballot return envelope.

They attempted to cast provisional ballots in place of the rejected mail-in ballots, but the county rejected those, too.

In the court decision, Judge Matt Wolf ordered Butler County to count the voters’ two provisional ballots.

Contesting the lawsuit was Butler County as well as the state and national Republican parties. Their lawyers had argued that nothing in state law allows a voter to cast a provisional ballot in place of a rejected mail-in ballot.

They have three days to appeal to the state Supreme Court.

The lawsuit is one of a handful being fought in state and federal courts over the practice of Pennsylvania counties throwing out mail-in ballots over mistakes such as forgetting to sign or write the date on the ballot’s return envelope or forgetting to put the ballot in a secrecy envelope.

The decision will apply to all 67 counties, lawyers in the case say. It’s not entirely clear how many Pennsylvania counties haven’t let voters replace a rejected mail-in ballot with a provisional ballot, although the plaintiffs’ lawyers listed nine other counties that they say may have had followed such a policy in April’s primary election.

The voters were represented by the American Civil Liberties Union of Pennsylvania and the Public Interest Law Center. The state Democratic Party and Democratic Gov. Josh Shapiro’s administration also took their side in the case.

Approximately 21,800 mail ballots were rejected in 2020’s presidential election, out of about 2.7 million mail ballots cast in Pennsylvania, according to the state elections office.