Arizona can require proof of citizenship on federal voter registration forms, a federal judge ruled Wednesday.

U.S. District Judge Eric Melgren ruled in Kansas City that the U.S. Election Assistance Commission (EAC) cannot deny requests from Arizona and Kansas to add state-specific requirements to a national voter registration form.

Both states passed laws requiring proof of citizenship in order to register to vote. The current federal form has a statement that the prospective voter affirms he or she is a citizen, without proof.

"The court finds that Congress has not preempted state laws requiring proof of citizenship," Melgren wrote in his ruling. "The court finds the decision of the EAC denying the states’ requests to be unlawful and in excess of statutory authority.”

He added the U.S. Constitution gives states power to set voter qualifications.

No more than a dozen voter fraud cases have been prosecuted in Arizona in the last decade, a span of time in which more than 3 million Arizonans have registered to vote, casting 10 million or more ballots in various elections. Most of those cases have involved U.S. citizens who registered to vote in Arizona and another state.

Attorney General Tom Horne has argued that there are a significant number of instances of voter fraud by undocumented immigrants, as evidenced by what he said were more than 200 non-citizen voter registrants found in Maricopa and Pima counties through questionnaires they filled out when called for jury duty.

Back in August, Arizona Secretary of State Ken Bennett and Horne joined forces with Kansas Secretary of State Kris Kobach and filed the lawsuit.

Gov. Jan Brewer led the push for such requirement as secretary of state with Proposition 200, which passed in 2004.

In July of last year, Brewer said it's the responsibility of state and local governments to protect the voting process, and that she backed efforts to ensure only citizens are voting.

The Associated Press Contributed to this report

Read the Voter Registration Ruling: View at Google Docs | Download File