The U.S. Supreme Court on Monday heard arguments about the constitutionality of Arizona's Proposition 200, a 2004 voter-approved measure that requires prospective voters to prove their citizenship before registering to vote.
The 9th U.S. Circuit Court of Appeals previously ruled the law unconstitutional because it requires more of prospective voters than the 1993 National Voter Registration Act, which requires states to accept a simple "Motor Voter" registration form on which registrants simply swear they are citizens.
Without the documentation requirement, Arizona officials say, a non-citizen could easily register to vote. The contested Arizona law requires people using the federal mail-in form to provide an Arizona driver's license number, or some proof of citizenship.
Supreme Court Justice Antonin Scalia seemed to side with the state, saying in court that swearing on paper—rather than documenting—that you're a citizen "is not proof at all."
Justice Anthony Kennedy said, however, that if states can ask would-be voters for additional information the intentionally easy-to-complete federal registration form "is not worth very much."
Among the spectators attending the hearing was retired Supreme Court Justice Sandra Day O'Connor, who is from Arizona and like Kennedy was often a swing vote. In October 2010 O'Connor served on a three-judge panel of the 9th Circuit Court that struck down the requirement.
In June 2012 the Supreme Court upheld the so-called "show me your papers" provision in Arizona SB 1070—a particularly contentious law aimed at curbing illegal immigration—but struck down other requirements that would have criminalized seeking work without legal residency and forced immigrants to always carry identification.