A federal appeals court on Friday upheld a signature portion of the Voting Rights Act, setting the stage for consideration by a Supreme Court whose majority is skeptical about the law’s continued viability.

On a 2 to 1 vote, a panel of the U.S. Court of Appeals for the D.C. Circuit turned down a challenge to Section 5 of the historic civil rights act, which requires states and localities with a history of discrimination to get federal approval of any changes in their voting laws.

First passed in 1965, the act was most recently extended in 2006. Conservative critics have said that despite lopsided votes in both houses and the approval of President George W. Bush, lawmakers did not do enough to justify extending the Section 5 restrictions on nine states, mostly in the South, and parts of seven others.

But U.S. Circuit Judge David S. Tatel said the judicial branch had no reason to second-guess Congress in reauthorizing the law.

“Congress drew reasonable conclusions from the extensive evidence it gathered” and was fulfilling its obligation to ensure “that the right to vote — surely among the most important guarantees of political liberty in the Constitution — is not abridged on account of race,” Tatel wrote. “In this context, we owe much deference to the considered judgment of the people’s elected representatives.”

The final word will almost surely come from the U.S. Supreme Court. Conservative activists and Republican attorneys general from some of the covered states — Alabama, Alaska, Arizona, Georgia, Louisiana, Mississippi, South Carolina, Texas and Virginia — have launched challenges to the law. They are encouraged by a 2009 Supreme Court decision that, as Tatel acknowledged in his opinion, raised substantial questions about Section 5’s continued constitutionality.

“Things have changed in the South,” Chief Justice John G. Roberts Jr. wrote in an opinion that avoided the constitutional questions. “Voter turnout and registration rates now approach parity. Blatantly discriminatory evasions of federal decrees are rare. And minority candidates hold office at unprecedented levels.”

Tatel said the 2009 decision required judges to examine two questions: whether the “current burdens” imposed by the act were justified by “current needs,” and whether the discrimination “evil” Section 5 was meant to eliminate is still concentrated in the jurisdictions singled out for “pre-clearance” by federal authorities.

Tatel, appointed by President Bill Clinton, joined with Circuit Judge Thomas B. Griffith, a Bush appointee, to say that Congress had met those standards. Senior Circuit Judge Stephen F. Williams, appointed by President Ronald Reagan, disagreed. Williams noted that Congress avoided a critical look at current conditions when it reauthorized the law in 2006 and based its decision on which jurisdictions are covered by using decades-old information.

“Of course sometimes a skilled dart-thrower can hit the bull’s eye throwing a dart backwards over his shoulder,” Williams wrote. “Congress hasn’t proven so adept.”

The Obama administration has pledged to increase its role in reviewing voting changes in jurisdictions covered by Section 5, and the Justice Department welcomed Friday’s ruling. “The Voting Rights Act is a cornerstone of civil rights law, and the department will continue to vigorously defend it against constitutional challenges,” it said in a statement.

The department has blocked new voter-ID laws in South Carolina and Texas; courts will consider those challenges this summer.

Friday’s decision came in a direct challenge to the law brought by Shelby County, which is in the heart of Alabama near Birmingham. Lawyer Bert Rein said the next step has not been planned.

But the lawsuit was designed to get the issue before the Supreme Court. It would add to a term next fall that already features a high-profile case involving race: the continued viability of affirmative action in college admissions.