Justices rule that the state's law requiring people to show proof of citizenship to register to vote is trumped by a federal law.
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WASHINGTON — The U.S. Supreme Court on Monday struck down an Arizona law that requires people registering to vote in federal elections to show proof of citizenship.
In a 7-2 vote, the court said the voter registration provision of the 2004 state law, known as Proposition 200, was trumped by a federal law, the 1993 National Voter Registration Act.
The federal law requires prospective voters to provide one of several possible forms of identification, such as a driver's license or a passport, but no proof of citizenship is needed. Would-be voters simply sign a statement saying they are citizens.
Landmark rulings on the way from Supreme Court
The 9th U.S. Circuit Court of Appeals said that the National Voter Registration Act, which doesn't require such documentation, trumps Proposition 200, and the high court agreed with the federal government in the case.
In the majority opinion, Justice Antonin Scalia said the state law was pre-empted by language in the federal statute saying that states must "accept and use" a federal registration form. The state law ordered officials to reject the form if there was no accompanying proof of citizenship.
Justices Clarence Thomas and Samuel Alito were the two dissenters.
The case began when Arizona residents, civil rights groups and Indian tribes sued to challenge the state measure, which they said discriminated against otherwise eligible voters, among them members of more than a score of Native American tribes across the rugged desert state, some of whom struggle to meet additional requirements.
Arizona, which shares a border with Mexico, has a reputation for passing tough anti-immigration laws that have brought it into conflict with the Obama administration.
Arizona officials say their law is needed to stop non-Americans from voting in elections, while opponents see it as an attack on minorities, immigrants and the elderly.
The Arizona voter registration measure is one of many nationwide championed by Republicans and put in place at the state level. Democrats say the measures are intended to make it more difficult for certain voters who tend to vote Democratic to cast ballots.
The case is Arizona v. Inter Tribal Council of Arizona, U.S. Supreme Court, No. 12-71.
The Associated Press contributed to this report.
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