When Pennsylvania officials begin their defense of the state's new voter identification law in court Wednesday, they will do so after agreeing to abandon a central argument for why such laws are needed.

In a Pennsylvania court filing, the state says it has never investigated claims of in-person voter fraud and so won't argue that such fraud has occurred in the past. As a result, the state says, it has no evidence that the crime has ever been committed.

The state also says it won't present "any evidence or argument" that in-person voter fraud is likely to occur on Election Day if the voter ID law isn't enacted.

More from the filing, which also was signed by the attorney for the plaintiffs, who are Pennsylvania residents suing to overturn the law:

"There have been no investigations or prosecutions of in-person voter fraud in Pennsylvania; and the parties do not have direct personal knowledge of any such investigations or prosecutions in other states...Respondents will not offer any evidence in this action that in-person voter fraud has in fact occurred in Pennsylvania or elsewhere."

The plaintiffs, represented by the American Civil Liberties Union and National Association for the Advancement of Colored People, include seniors and other registered voters who say the new ID requirement creates unlawful barriers to voting.

On Tuesday, hundreds of demonstrators protested the law outside the state capitol. They say the law violates the Voting Rights Act by discriminating against minorities.

The Justice Department is investigating whether minority voters are disproportionately represented among those who lack proper ID under the new law.

Pennsylvania Secretary of the Commonwealth Carol Aichele told reporters after the protest that roughly 85,000 voters will need a newly created voter ID card to be issued free. She said her office is cooperating with the Justice Department and defended the law.

"The law is valid and will sustain any kind of test," she said.

The prevention of voter fraud is the most frequently cited reason for the passage of state voter ID laws, the strictest of which, including Pennsylvania's, require voters to present government-issued photo IDs.

Other states, most of which are led by Republicans, defending the laws in ongoing legal battles say the specter of fraud justifies requiring voters to verify their identity at the polls. The Supreme Court affirmed that argument by upholding Indiana's voter ID law in 2008, ruling that states have a "valid interest" in deterring fraud.

Texas, Wisconsin and South Carolina are among the other states fighting lawsuits to block their voter ID laws. Most of the challenges have been brought by voting and civil rights activists.

The Justice Department also has filed lawsuits to block several of the laws from being enacted, saying they would disenfranchise minority voters.

A recent report by the Brennan Center for Justice found that half a million likely voters in 10 of the stricter photo ID states don't have access to a vehicle and live more than 10 miles from offices that issue the IDs.

Democrats critical of the laws cite the findings of a federal panel that voter fraud is rare. They say the laws are intended to suppress turnout among minorities, young adults and others who tend to vote for Democratic candidates.

The Pennsylvania law fanned partisan flames when Republican state House Majority Leader Mike Turzai, who helped pass the law, said at a party gathering: "Voter ID ... is going to allow [presumptive GOP presidential nominee] Gov. [Mitt] Romney to win the state of Pennsylvania, done."

(A spokesman for Turzai later said the lawmaker meant that "for the first time in a long while, the Republican presidential candidate will be on a more even keel thanks to voter ID.")

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