Last week, a flurry of litigation in Pennsylvania clarified the rules for mail balloting there. In short, mail ballots will still be rejected in the key battleground state if voters fail to properly date the affidavits that accompany their ballots — but voters who make any mistake with their mail ballots will be able to vote by provisional ballot instead on Election Day.

Thousands of mail-in ballots in the battleground state of Pennsylvania have been targeted for rejection as part of a last-minute campaign that has set off alarms for voting rights groups and exasperated local election officials.