U.S. District Judge Lynn Adelman in Milwaukee ruled Tuesday the requirements impose an unfair burden on poor and minority voters. Republican Attorney General J.B. Van Hollen has promised to appeal.
Van Hollen isn't running for re-election. Jon Richards, Ismael Ozanne and Susan Happ are vying for the Democratic nomination. Brad Schimel is the only Republican in the race.
Schimel says he would appeal the ruling if he were attorney general as well. He says voter ID is the only way to ensure each person's vote counts only once.
Richards, Ozanne and Happ's campaigns all issued statements praising the decision.