U.S. government says Texas voter ID law targets minorities WASHINGTON (Reuters) - A Texas law supported by Republicans requiring voters to have photo identification was passed to discourage Hispanics and African-Americans from casting ballots, an expert witness for the U.S. government testified in a landmark trial on Tuesday. But lawyers for the state of Texas said the federal government was exaggerating the number of people who would not be eligible to vote under the law passed in 2011. The federal government has blocked the law and Texas has sued to overturn the decision. California Institute of Technology Professor Morgan Kousser, an expert on race and voting rights in the United States, told the court the Texas law was racially motivated to keep whites in power in the nation's second most populous state. "There was considerable concern among non-Hispanic whites about losing control," he told the court. There is such a correlation between partisanship and race that any bill that has partisan effects would have racial effects. Texas lawyers cited polls showing that a majority of Hispanic and black voters supported the law, but Kousser said those polls were worded unfairly in order to garner support. 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. 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. 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. Editing by Corrie MacLaggan, Greg McCune and David Brunnstrom