WASHINGTON – The Supreme Court’s conservative majority strongly suggested Wednesday that a key portion of the landmark legislation protecting minority voting rights is no longer justified and that the time had come for Southern states to be freed from special federal oversight.

At stake was Section 5 of the Voting Rights Act of 1965, which even its challengers credit with delivering the promise of political inclusion to minority voters and eventually leading to the election of the nation’s first African-American president.

The sharp ideological differences that mark the court have rarely been more on display than in Wednesday’s dramatic and at times tense oral argument, which played out before a courtroom filled with political leaders such as House Majority Leader Nancy Pelosi and civil rights activists such as Rep. John Lewis, D-Ga., and Rev. Jesse Jackson.

The justices’ questioning of the lawyers was so intense that Chief Justice John Roberts Jr. allowed the session to run into overtime.

At issue was Section 5 of the law, which requires nine states, mostly in the South, and jurisdictions in other states to “pre-clear” any changes in voting laws with federal authorities.

Justice Antonin Scalia said Congress’ decision in 2006 to re-authorize the law was not the result of a studied decision but of a “phenomenon that is called perpetuation of racial entitlement.” Politicians, he said, are afraid to vote against something with the “wonderful” name of the Voting Rights Act.

The liberals on the court aggressively defended the re-authorization, saying Congress amassed overwhelming evidence of a continued need for Section 5, which covers Alabama, Georgia, Louisiana, Mississippi, South Carolina, Texas and Virginia, as well as Alaska and Arizona, plus parts of seven other states.

“I don’t know what they’re thinking exactly,” Justice Stephen Breyer said of the nearly unanimous majorities in Congress that reauthorized Section 5. “But it seems to me one might reasonably think this: It’s an old disease, it’s gotten a lot better, a lot better, but it’s still there.”

The court in 2009 previously considered whether the extension of Section 5 was constitutional. The justices decided that case without a definitive answer but sent an unmistakable message to Congress that the court was dissatisfied with the formula used to determine which states were covered by Section 5.

Justice Samuel Alito Jr. called the Voting Rights Act “one of the most successful statutes that Congress passed in the Twentieth Century ” but nevertheless said the selection of jurisdictions covered by Section 5 made no sense today.

The law was being challenged by Shelby County, Ala., a growing suburb south of Birmingham. The county was represented by Bert Rein, a Washington lawyer who said today’s Alabama bore “no resemblance” to the state that earned its spot on the 1965 list.

“You’re objecting to a formula, but under any formula that Congress could devise, it would capture Alabama,” said Justice Elena Kagan, citing findings that a greater proportional number of violations of the act occur in the South.