PHOENIX — The U.S. Supreme Court agreed this morning to consider how far Arizona — and other states — can go in requiring voters to prove citizenship when registering.

In a brief order, the justices agreed to review a ruling by the 9th U.S. Circuit Court of Appeals that Arizona is required to accept a form prepared by the federal Election Assistance Commission and allow people to register. That form does not mandate proof of citizenship but instead simply requires a signed avowal the person is eligible to vote.

The state is asking the nation's high court to overturn that ruling.

At the heart of the fight is a 2004 voter-approved measure which requires both proof of citizenship to register and identification to cast a ballot at the polls.

Foes challenged both.

The courts sided with the state on the ID portion. But they rejected the citizenship proof.

In one of those lower rulings, Judge Sandra Ikuta of the 9th circuit pointed out that Congress mandated creation of a specific form designed to allow individuals to register to vote by mail. That form does not include a proof-of-citizenship requirement.

What that means, the judge said, is Arizona election officials have to register those people who sign up using that federal form, even if they do not provide the state-mandated identification.

Arizona has remained free, however, to continue to demand proof of citizenship from those who go to state offices and register using a state-provided form.

In seeking review, attorneys for the state argue that the mandate for proof of citizenship "imposes a minimal burden on a limited number of persons and furthers the federal government's and the states' broad interest in protecting election integrity.''

But foes, lead by the Inter-Tribal Council of Arizona, said Congress enacted the National Voting Rights Act because "unfair and discriminatory voter registration laws had depressed voter registration, particularly among minority and low-income voters.'' What Congress wanted, they told the court, was a uniform way that voters could register.

It was that law that directed the Election Assistance Commission to create the federal form that does not require proof of citizenship.

Senior Editor, News, Arizona Daily Star, Tucson, Az.