The Ninth Circuit Court of Appeals has overturned Arizona’s requirement that people show proof of citizenship to register to vote.

The split decision by a three-judge panel determined that the requirement to show proof of citizenship — passed by voters in 2004 — is not consistent with the National Voter Registration Act.

Associate Justice Sandra Day O’Connor, temporarily sitting by designation, and Circuit Judge Sandra Ikuta, with chief judge Alex Kozinski dissenting, said Prop. 200 creates an additional hurdle, while the national act is intended to reduce “state-imposed obstacles” to registration.