The Department of Justice filed a lawsuit against Arizona over a state law requiring voters to show proof of citizenship in order to vote in presidential elections. The new law, which also affects voting by mail in any federal election, “turns the clock back on progress” and constitutes a “textbook violation” of federal law—specifically, the National Voter Registration Act and the Civil Rights Act of 1964, according to DOJ. In March, when the when the law was passed, Arizona Republicans contended that it would prevent voter fraud. Rep. Paul Gosar (R) called the lawsuit “frivolous,” saying on Tuesday that “showing your ID to vote is easy, common and necessary.” The suit recalls a similar episode in Arizona in 2013, when the U.S. Supreme Court struck down a 2005 law requiring proof of citizenship to vote in federal elections.