By Drew Singer
WASHINGTON (Reuters) - Lawyers for Texas and the federal government clashed on Tuesday over how many people could be barred from casting ballots under a state law requiring voters to present photo identification, in a landmark case that could end up before the U.S. Supreme Court.
A study cited by the U.S. government says that 1.5 million Texas voters lack the photo identification required to vote, a figure that lawyers for Texas say is vastly inflated.
"It's a mess," District Judge Rosemary Collyer, one of three judges hearing the case, said of the disparity. Speaking on the second day of the week-long trial, Collyer stressed the importance of figuring out the differences.
Texas hopes that a three-judge panel of the U.S. District Court for the District of Columbia overturns the Justice Department's March decision to block the law based on the Voting Rights Act of 1965.
Supporters of Texas also hope the case will force the U.S. Supreme Court to rule whether the Voting Rights Act, enacted during the Civil Rights Era to protect minority voters, has outlived its usefulness.
The trial over the Texas law is the first challenge to the federal government's power to block such a voter ID law since the Democratic administration of President Barack Obama took office in January 2009.
Each side told the court that flaws in the other's study severely tainted their tallies.
The Justice Department has cited a study by Harvard University Professor Stephen Ansolabehere that found the Texas law would force nearly 2 million people to get new photo IDs or be unable to vote in the next election.
A disproportionately large number of those voters are Hispanic and black, the department said.
Texas presented a study by University of Texas Professor Thomas Sager that showed the total figure was closer to 167,000 and that the Harvard study inflated the effect on minorities.
Justice Department lawyers attacked Sager's findings, noting that he added 6 million people to the list of Texans with proper IDs even though their licenses were expired or they didn't have proper ID at all.
Seventeen states have passed some version of a law requiring voters to present photo ID at the polls. The Justice Department has also blocked a South Carolina law citing the Voting Rights Act, but the challenge has yet to reach court.
The Texas lawsuit for approval of the voter identification law is: State of Texas v. Holder in U.S. District Court for the District of Columbia, No. 12-cv-128. The judicial panel is composed of Appeals Judge David Tatel, District Judge Robert Wilkins and District Judge Rosemary Collyer.
(Editing by Corrie MacLaggan and Xavier Briand)