AUSTIN, Texas — Former President Bill Clinton used the 50th anniversary of the Civil Rights Act to criticize efforts in several states to restrict voting, notably photo identification requirements, saying they threaten to roll back half a century of progress.

Clinton spoke Wednesday night during the Civil Rights Summit at the Lyndon B. Johnson Presidential Library at the University of Texas in Austin. The library is hosting the three-day event to mark the anniversary of the landmark 1964 law that banned widespread discrimination against racial and ethnic minorities and women.