In an unusual move, the U.S. Court of Appeals for the Ninth Circuit agreed to rehear a case that challenged Arizona’s 2004 law that required its residents to show proof of citizenship when registering to vote.

The law in question, Proposition 200, was passed by Arizona voters in 2004. It requires applicants to provide any of a number of state or federal documents evidencing their citizenship, such as a driver’s license, passport, birth certificate, tribal identification or a naturalization certification number.

Azcentral.com reporter Alla Beard Rau wrote in “Ruling on Arizona voter law to be reconsidered” that the appeals court had previously ruled that a federal law, the National Voter Registration Act, pre-empted the state law. That act only requires applicants to sign a statement that they are citizens and does not require any documented proof. The law was designed to create a federal standard that all states are required to adopt.

In last October’s 2-1 ruling, the court also stated that the federal law was intended to remove obstacles to voter registration, which the Arizona proposition apparently created. Many African-Americans recall past voter discrimination laws in the South that required poll taxes or literacy tests to register, which many poor and indigent citizens were unable to meet.

Arizona Secretary of State Ken Bennett was relieved at the court’s decision, stating that the law merely ensures the integrity of the election process and only mandates a simple demonstration of proof of citizenship.

The case will be heard en banc, or by all 11 judges of the court.