Pennsylvania Supreme Court Says Mail-In Ballots Without Dates Should Not Be Counted

The Pennsylvania Supreme Court on Tuesday ordered election officials in the battleground state to refrain from counting mail-in ballots that lack a written date on their outer envelope, siding with Republicans in a matter that could have national implications on Nov. 8.

The Republican National Committee and several other party-aligned groups filed a lawsuit in October to stop undated ballots from being counted, citing a state law that requires voters to write the date on the return envelope when sending them in.

In a two-page ruling issued a week before Election Day, the court said that noncompliant ballots should be set aside. It was the latest wrinkle in a protracted legal fight over undated ballots in Pennsylvania, where voters are set to decide pivotal contests for governor and the U.S. Senate.

But the six justices were split about whether their rejection violated the voting protections of the federal Civil Rights Act. Three Democrats on the elected court said that it did violate federal law, while a fourth Democrat, Kevin M. Dougherty, joined the court’s two Republicans in saying that it did not. (The court typically has seven members, but Chief Justice Max Baer, a Democrat, died in September.)

The court’s ruling directly conflicted with guidance issued in September by Leigh M. Chapman, a Democrat who is the acting secretary of the commonwealth and said ballots without a date on them should be counted as long as they are returned on time.

It was not immediately clear whether state election officials could pursue an appeal.

“We are reviewing, but the order underscores the importance of the state’s consistent guidance that voters should carefully follow all instructions on their mail ballot and double-check before returning it,” Amy Gulli, a spokeswoman for Ms. Chapman, said in an email on Tuesday night.

Voters who are concerned that they might have made an error on ballots before returning them should contact their county election board or the Pennsylvania Department of State, Ms. Gulli said.

Pennsylvania is where two of the most closely watched elections in the country will be decided next week. In the governor’s race, Josh Shapiro, the state’s Democratic attorney general, faces state Senator Doug Mastriano, the right-wing, election-denying Republican nominee. And control of the U.S. Senate could hinge on the outcome of the contest between the celebrity physician Dr. Mehmet Oz, a Republican, and Lt. Gov. John Fetterman, a Democrat.

Ronna McDaniel, the R.N.C. chairwoman, heralded the ruling as a “massive victory for Pennsylvania voters and the rule of law.”

“Republicans went to court, and now Democrats and all counties have to follow the law,” she said. “This is a milestone in Republicans’ ongoing efforts to make it easier to vote and harder to cheat in Pennsylvania and nationwide.”

Lawrence Tabas, the chairman of the state Republican Party, said the decision was a “tremendous win for election integrity.”

The American Civil Liberties Union of Pennsylvania lamented the ruling on Tuesday night on Twitter.

“We’re disappointed,” the group said. “No one should be disenfranchised for an irrelevant technicality. Voters, sign and date your return envelope.”

The Democratic National Committee and the state Democratic Party, which were not named as respondents in the lawsuit, did not immediately respond to requests for comment on Tuesday night.

Neither did the campaigns of Mr. Fetterman and Dr. Oz.

The issue of undated ballots was a major point of contention in Dr. Oz’s primary in May, which was decided by less than 1,000 votes and triggered an automatic recount.

Dr. Oz had opposed the counting of about 850 undated ballots that were cast in that race. His opponent, David McCormick, sued to include the ballots, calling the date requirement irrelevant. He later conceded the race.

And last year, a Republican candidate who lost a judicial race in Lehigh County sued to stop undated ballots from being counted in that contest, a case that escalated all the way to the U.S. Supreme Court.

In May, the U.S. Court of Appeals for the Third Circuit in Philadelphia ruled against that candidate, David Ritter. The Supreme Court said in June that election officials in Pennsylvania may count mailed ballots that were received by the cutoff date but not dated. But in early October, the Supreme Court vacated the appeals court ruling.

Mail-in ballots must be received by county election boards by 8 p.m. on Election Day, otherwise they won’t be counted.

Nick Corasaniti contributed reporting.