WASHINGTON -- The Supreme Court upheld Indiana's voter identification law yesterday, concluding in a splintered decision that the challengers failed to prove that the law's photo ID requirement placed an unconstitutional burden on the right to vote.
The 6-3 ruling kept the door open to future lawsuits with more evidence. But this was small comfort to the dissenters or to critics of voter ID laws, who predicted that a more likely outcome would be the spread of measures that would keep some legitimate would-be voters from the polls.
Voting experts said the ruling was likely to complicate election administration, leading to more litigation and more legislation, at least in states with Republican legislative majorities, but would probably have a limited impact on this year's presidential voting.
The issue has been intensely partisan, with Republicans supporting increased identification requirements for voters and Democrats opposing them.
In what the court described as the "lead opinion" - written by Justice John Paul Stevens and joined by Chief Justice John G. Roberts Jr. and Justice Anthony M. Kennedy - it acknowledged that the record of the case contained "no evidence" of the type of voter fraud the law was ostensibly devised to deter, the attempt by a voter to cast a ballot in another person's name.
But Stevens said that neither was there "any concrete evidence of the burden imposed on voters who now lack photo identification." The "risk of voter fraud" was "real," he said, and there was "no question about the legitimacy or importance of the state's interest in counting only the votes of eligible voters."
The three others who made up the majority, Justices Antonin Scalia, Clarence Thomas and Samuel A. Alito Jr., said in an opinion by Scalia that the law was obviously justified as "a generally applicable, nondiscriminatory voting regulation."
In a dissenting opinion, Justice David H. Souter said that for those on whom the law had an impact, the burden was "serious" and the state had failed to justify it. Like the Virginia poll tax the court struck down 42 years ago, he said, "the onus of the Indiana law is illegitimate just because it correlates with no state interest so well as it does with the object of deterring poorer residents from exercising the franchise."
The other dissenters were Justices Ruth Bader Ginsburg and Stephen G. Breyer.
Six states in addition to Indiana - Florida, Georgia, Hawaii, Louisiana, Michigan and South Dakota - now require voters to provide photo identification before casting a ballot. Bills are pending in two dozen other states, although they are not likely to pass this year in more than a handful, due to short legislative sessions and Democratic opposition.
The Indiana law, adopted by the Republican-controlled legislature in 2005, is regarded as the strictest in the country. It requires a voter to present a photograph as part of an unexpired document issued either by Indiana or the federal government, a requirement that in most cases can be satisfied only by a current driver's license or a passport. The state's motor vehicle agency provides a free photo ID card for people who do not drive, but obtaining it requires a "primary document" like an original birth certificate or a passport.
Would-be voters without proper identification may cast a provisional ballot that will be counted only if they appear within 10 days at a county clerk's office and present acceptable photo identification or, alternatively, swear either that they are indigent or that they have a religious objection to being photographed.
The Indiana law was challenged in separate suits filed by the Indiana Democratic Party and by another group of plaintiffs that included elected officials and community groups.
In Maryland, voters have to state their address as part of confirming who they are, but do not have to show identification to vote. The push to require ID comes up year after year in Maryland and is regularly defeated, lawmakers said.
In the recently concluded legislative session, various bills either to require photo identification or strengthen penalties for voter fraud were all voted down by committees.
Del. Jon S. Cardin, a Baltimore County Democrat and one of the General Assembly's foremost experts on election law, said there have been only a handful of cases of suspected voter fraud in the past 20 years in the state.
"There's really no reason to enhance the voter ID requirements," he said. "There has been absolutely no positive evidence of any fraudulent voting based on improper identification. It just hasn't been a problem."
Sun reporter Bradley Olson contributed to this article.