WASHINGTON (AP) -- States can require voters to produce photo identification, the Supreme Court ruled Monday, upholding a Republican-inspired law that Democrats say will keep some poor, older and minority voters from casting ballots.
Twenty-five states require some form of ID, and the court's 6-3 decision rejecting a challenge to Indiana's strict voter ID law could encourage others to adopt their own measures. Oklahoma legislators said the decision should help them get a version approved.
The ruling means the ID requirement will be in effect for next week's presidential primary in Indiana, where a significant number of new voters are expected to turn out for the Democratic contest between Sens. Hillary Rodham Clinton and Barack Obama.
The results could say something about the effect of the law, either because a large number of voters will lack identification and be forced to cast provisional ballots or because the number turns out to be small.
Supporters of the law say it's all about preventing fraud.
Indiana has a "valid interest in protecting 'the integrity and reliability of the electoral process,'" said Justice John Paul Stevens in an opinion that was joined by Chief Justice John Roberts and Justice Anthony Kennedy.
Stevens said that Indiana's desire to prevent fraud and to inspire voter confidence in the election system are important even though there have been no reports of the kind of fraud the law was designed to combat. Evidence of voters being inconvenienced by the law's requirements also is scant. For the overwhelming majority of voters, an Indiana driver's license serves as the identification.
The law does not apply to absentee balloting, where election experts agree the threat of fraud is higher.
The Indiana law was passed in 2005. Democrats and civil rights groups opposed it as unconstitutional and called it a thinly veiled effort to discourage groups of voters who tend to prefer Democrats.
It was in effect during the 2006 elections when Democrats picked up three congressional seats in Indiana and won control of the state House of Representatives.
Justices Samuel Alito, Antonin Scalia and Clarence Thomas agreed with the outcome Monday, but wrote separately in favor of a broader defense of voter ID laws.
"The universally applicable requirements of Indiana's voter-identification law are eminently reasonable. The burden of acquiring, possessing and showing a free photo identification is simply not severe, because it does not 'even represent a significant increase over the usual burdens of voting,'" Scalia said.
Justices Stephen Breyer, Ruth Bader Ginsburg and David Souter dissented.
Indiana's voter ID law "threatens to impose nontrivial burdens on the voting rights of tens of thousands of the state's citizens," Souter said.
The targets of the law, he said, are "voters who are poor and old."
Yet Stevens wrote that the law does not single out groups of voters for different treatment. "We cannot conclude that the statute imposes 'excessively burdensome requirements' on any class of voters," he said. That opinion suggested the outcome could be different in a state where voters could provide evidence that their rights had been impaired.