In a significant ruling, the Ninth Circuit Court of Appeals has upheld a new Arizona law requiring proof of citizenship for voter registration. The decision comes as a victory for election integrity advocates who argue that only U.S. citizens should be allowed to vote.

The law, which was challenged by several civil rights groups, requires individuals to provide documentary proof of citizenship when registering to vote using a state form. Those who fail to do so will have their registration applications rejected.

The Ninth Circuit's decision is a reversal of a lower court's ruling that had blocked the law from taking effect. In its opinion, the appellate court found that the requirement does not violate the National Voter Registration Act or the U.S. Constitution.

"The plain language of the National Voter Registration Act reflects an intent to regulate all elections for federal office, including for president or vice president," wrote the court in its opinion. "The Act does not preempt state laws requiring proof of citizenship for voter registration."

The court also rejected the argument that the law disproportionately impacts minority voters. "The plaintiffs have failed to demonstrate that the law has a disparate impact on minority groups," the court stated.

The ruling is a major win for Arizona Republicans, who have long argued that stricter voter registration requirements are necessary to prevent voter fraud. "This decision reaffirms the right of states to ensure the integrity of their elections," said Arizona Attorney General Mark Brnovich.

However, the decision is likely to be appealed to the U.S. Supreme Court. The American Civil Liberties Union, which represents the plaintiffs in the case, has vowed to continue fighting the law. "We are deeply disappointed by the Ninth Circuit's decision," said ACLU attorney Cecillia Wang. "We will continue to fight to protect the right to vote for all eligible Americans."

The decision comes as several states have passed or are considering similar voter registration requirements. The outcome of this case could have significant implications for the future of voting rights in the United States.