A federal appeals court ruled Wednesday that Texas' voter ID law has a "discriminatory" effect on minorities in a victory for President Barack Obama, whose administration took the unusual step of bringing the weight of the U.S. Justice Department to fight a wave of new ballot-box restrictions passed in conservative statehouses.

The 5th U.S. Circuit Court of Appeals ruled that the 2011 Texas law runs afoul of parts of the federal Voting Rights Act — handing down the decision on the eve of the 50th anniversary of the landmark civil rights law.

Texas was allowed to use the voter ID law during the 2014 elections, thereby requiring an estimated 13.6 million registered Texas voters to have a photo ID to cast a ballot.

The ruling was a victory, albeit not a sweeping one, for Democrats and minority rights groups. Whereas a Texas federal judge last year called the voter ID law the equivalent of a poll tax, a three-judge panel of the New Orleans court disagreed. It instead sent the law back to the lower court to consider how to fix the discriminatory effects.

Until then, Republican Texas Attorney General Ken Paxton said the law will remain in effect, though he did not acknowledge the issues raised by court's mixed ruling.

"I'm particularly pleased the panel saw through and rejected the plaintiffs' claim that our law constituted a 'poll tax.' The intent of this law is to protect the voting process in Texas, and we will continue to defend this important safeguard for all Texas voters," Paxton said.

Other Republican-controlled states, including Wisconsin and North Carolina, have passed similar voter ID measures in recent years, but the Texas law signed by then-Gov. Rick Perry is widely viewed as one of the nation's toughest. It requires one of seven forms of approved identification, but unlike other states with voter ID restrictions, Texas doesn't recognize university IDs from college students. It does, however, accept concealed handgun licenses as proof of identity.