The US Supreme Court [official website] ruled [opinion, PDF] 7-2 Monday in Arizona v. Inter Tribal Council [SCOTUSblog backgrounder] that Arizona's law requiring that proof of citizenship be provided in order to register to vote is preempted by federal law. The court found that Proposition 200 [text] is preempted by the National Voter Registration Act (NVRA) [official website], which requires states to use the federal voter registration form. The NVRA was passed in 1993 with the purpose of increasing voter registration by removing state imposed barriers. Justice Antonin Scalia delivered the opinion of the court: "We hold that 42 USC §1973gg-4 precludes Arizona from requiring a Federal Form applicant to submit information beyond that required by the form itself." The opinion preserved states' rights to ultimately control who may vote, by stating that "Arizona may, however, request anew that the [Election Assistance Commission] include such a requirement among the Federal Form's state-specific instructions, and may seek judicial review of the EAC's decision under the Administrative Procedure Act."
Justices Clarence Thomas and Samuel Alito dissented separately, and Justice Anthony Kennedy wrote a concurring opinion. Thomas based his dissent on his interpretation of the Constitution, in which "The States, not the Federal Government, have the exclusive right to define the 'Qualifications requisite for Electors,' ... which includes the corresponding power to verify that those qualifications have been met." Alito, in his dissent, wrote that "Properly interpreted, the NVRA permits Arizona to require applicants for federal voter registration to provide proof of eligibility." The court heard oral arguments in the case in March, and granted certiorari [JURIST reports] in October. The Ninth Circuit struck down [JURIST report] the proof of citizenship requirement last year while upholding a provision requiring voters to present photo ID at the polls.