The Supreme Court said Tuesday it won’t hear civil rights groups’ appeal seeking to invalidate Pennsylvania’s dating requirement for mail ballots, which has invalidated thousands of votes each recent election and become a central legal fight over voting in the key swing state.

The U.S. Supreme Court declined on Tuesday to hear a bid by civil and voting rights groups to end Pennsylvania's mandate that mail-in ballots bear a handwritten date on the outer envelope, a requirement they contend is unnecessary and has resulted in needless disqualification of legitimate ballots.

The US Supreme Court on Tuesday declined to hear a challenge to Pennsylvania's mail-in ballot date requirements. The plaintiffs in the class action lawsuit include the NAACP, the American Civil