The ruling came just after 5 a.m. on Saturday. Three justices dissented.
The Associated Press writes: "The law was struck down by a federal judge last week, but a federal appeals court had put that ruling on hold. The judge found that roughly 600,000 voters, many of them black or Latino, could be turned away at the polls because they lack acceptable identification. Early voting in Texas begins Monday."
NPR's Nina Totenberg tells Weekend Edition Saturday the Texas law is probably "the strictest in the country," but that the Supreme Court fully expects to rule on the constitutionality of the law at a later date.
"For now, the Justice Department has lost a big case," Nina tells WESAT host Scott Simon. "Because in the state of Texas this is going to go forward to the detriment of, probably, many, many voters."
Denniston says: "The Justice Department has indicated that the case is likely to return to the Supreme Court after the appeals court rules. Neither the Fifth Circuit Court's action so far nor the Supreme Court's Saturday order dealt with the issue of the law's constitutionality. The ultimate validity of the law, described by Saturday's dissenters as 'the strictest regime in the country,' probably depends upon Supreme Court review."
In a statement issued by the Department of Justice later, Attorney General Eric Holder called the decision "a major step backward."
Justices Ruth Bader Ginsburg, Sonia Sotomayor and Elena Kagan dissented.
"The greatest threat to public confidence in elections in this case is the prospect of enforcing a purposefully discriminatory law, one that likely imposes an unconstitutional poll tax and risks denying the right to vote to hundreds of thousands of eligible voters," Ginsburg wrote in the dissent.
Carl Tobias, a professor at the University of Richmond School of Law, tells NPR that Ginsburg cites the 2006 Supreme Court case Purcell v. Gonzales, which warns against changing voting rules too close to elections.
Ginsberg concludes that the district court's finding that the Texas law "'was enacted with a discriminatory purpose [and] operates as discriminatory poll tax' substantially outweigh, in her words, the minimal 'risk that the district court's injunction will in fact disrupt Texas' electoral processes,'" Tobias says.
In her dissent, Ginsburg points out that for about 400,000 Texas voters, they'd have to make a three-hour round trip to get the kind of identification that the state would accept at the polls.
The AP says of the Texas law that it "sets out seven forms of approved ID — a list that includes concealed handgun licenses but not college student IDs, which are accepted in other states with similar measures."