While Justice Antonin Scalia is known as an outspoken conservative, he did not approve of Arizona's law requiring proof of citizenship for voters. The opinion he penned for the U.S. Supreme Court, however, suggests a potential avenue for Arizona to get its way.
In a 7-2 ruling, the Court struck down an Arizona voter-registration provision enacted by voters in 2004, because it is pre-empted by the National Voter Registration Act (NVRA), a federal law passed in 1993.
The NVRA requires voters to simply check a box on a form, swearing by penalty of perjury that they're citizens of the United States. But Arizona's law went far beyond this.