In a ruling that raises more questions that it resolves, the U.S. Supreme Court struck down Arizona’s proof-of-citizenship requirement for federal voter registration forms.

In Arizona v. Inter Tribal Council of Arizona, Inc., a 7-2 majority determined that the National Voter Registration Act of 1993 preempts the state requirement. In the short term, this means that those who register to vote through a federal form only need to sign the form, swearing to be U.S. citizens. Georgia, Kansas and Alabama have proof-of-citizenship requirements identical to Arizona's, which also seem to be negated now. But in reacting to the court's decision, detractors of the nullified state requirement said they were still concerned about a back-door option created by the ruling.

“What the Supreme Court gave the federal government with one hand, it suggested could soon be taken away with the other,” wrote Richard Hasen, a political science professor from the University of California, Irvine School of Law, in a column for The Daily Beast.* That’s because the ruling allows Arizona to ask the federal Election Assistance Commission to add proof-of-citizenship as part of the federal registration form; if the commission -- which currently has no appointed commissioners -- rejected the request, then the state could take that request to court.

In the majority opinion, Justice Antonin Scalia wrote that while the federal government could decide the time, place and manner of federal elections, it must defer to states on deciding who can vote. Thus, the opinion suggests that further litigation could lead to a favorable outcome for Arizona. In a written statement, Tom Horne, the Arizona attorney general, said the decision outlined “a clear path to victory” and that “Arizona should use it.”

"I just think the path forward for Arizona is not all that clear," said Brenda Wright, vice president of legal strategies for Demos, a public policy nonprofit that helped file an amicus brief to the Supreme Court against the Arizona requirement. Wright said that the absence of sitting EAC commissioners does not automatically mean Arizona's request for amending the federal form would be granted by court order. "There’s a long distance to get from here and there."

In arguing for the proof-of-citizenship requirement before the court, Horne said the federal requirement for a signature verifying citizenship was “essentially an honor system. It does not do the job.” Justice Sonia Sotomayor responded, “Well, that's what the Federal system decided was enough.”

Much of the debate during the hearing in March centered on whether the federal law excluded additional requirements to verify citizenship. Horne argued that the federal form, with a signature, provided a minimum standard. But Justices Sotomayor and Elena Kagan’s questions suggested that additional layers of screening amounted to a different form, making the federal one worthless.

“What would be the purpose of requiring a federal form if you could just say, and in addition to that, you have to give ten more items of information?” Kagan asked. “I mean, then the federal form just becomes another hoop to jump through.”

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For groups that see the Arizona requirement as a burden on voting rights -- and worry about the prospects of further litigation -- the debate may turn from a question over administrative jurisdiction in elections to equal rights protections, said Rob Richie, executive director of FairVote, a nonprofit that advocates broader voter access and participation.

“The 7-2 majority included the four more liberal justices,” Richie noted, “and you might imagine they would be sympathetic to equal protection arguments.”

The ruling may not impact many would-be voters in Arizona. Less than 4 percent of registrations, about 2,000 people, in the last election cycle came from the federal form, according to Matt Roberts, a spokesman from the Arizona Secretary of State’s office. The Supreme Court ruling does not change requirements on the state voter registration form, which also asks for proof of citizenship, and can continue to do so after the ruling.

Then again, before the requirement became tied up in courts, the state did reject some 30,000 federal registrations that lacked additional proof of citizenship, beyond the federally required signature. "I don’t think that’s a minor impact at all," Wright said.

*This story has been updated to reflect the correct University of California school with which Rick Hasen is affiliated.