Correction: An earlier version of this story misstated the year of the law’s passage. Congress passed the measure in 1965, not 1964. This version has been updated.

In this Aug. 6, 1965, photo, President Lyndon Baines Johnson signs the Voting Rights Act of 1965 in a ceremony in the President's Room near the Senate Chambers on Capitol Hill in Washington. (AP)

The Supreme Court said Friday it will review a key provision of the Voting Rights Act that has been the federal government’s most forceful tool in protecting minority rights at the polls. The decision ensures that race and civil rights will be the hallmark of the current Supreme Court term.

The challenge to Section 5 of the 1965 Voting Rights Act was launched two years ago, and the court added it to its docket just days after an energized minority electorate played a critical role in the reelection of President Obama, the nation’s first African American president.

The justices said they would decide whether Congress exceeded its authority in 2006 when it reauthorized a requirement that states and localities with a history of discrimination, most of them in the South, receive federal approval before making any changes to their voting laws.

Three years ago, the court expressed concern about subjecting some states to stricter standards than others using a formula developed decades ago. But the justices sidestepped the constitutional question and found a narrow way to decide that case.

Friday’s decision to accept the challenge from Shelby County, Ala., is the court’s second major case this term involving race. Last month, the justices heard a challenge to the University of Texas’s admissions policy that could redefine or eliminate the use of affirmative action in high-
er-education admissions.

An analysis of the 2011-2012 Supreme Court session, including justice voting patterns and key cases.

This month, the court will decide whether to take up another civil rights issue: same-sex marriage. Two appeals courts have declared unconstitutional the federal Defense of Marriage Act, which denies federal recognition of same-sex marriages performed in states where it is legal. The court must also decide whether to intervene in a decision by federal courts to overturn California’s Proposition 8, which amended the state constitution to define marriage as only between a man and a woman.

The Section 5 requirements were passed during the darkest days of the civil rights struggle, paving the way for expanded voting rights for African Americans and greatly increasing the number of minority officeholders.

But critics say that the method for selecting the places subject to the special supervision — which include nine states and parts of seven others — is outdated. They say Congress should have spent more time investigating whether those classifications still made sense.

“The America that elected and reelected Barack Obama . . . is far different than when the Voting Rights Act was first enacted in 1965,” said Edward Blum of the Project on Fair Representation, which brought the challenge. “Congress unwisely reauthorized a bill that is stuck in a Jim Crow-era time warp.”

But the law’s defenders said it has proved its worth just in this election. Courts put on hold redistricting changes in Texas and voter ID laws in Texas and South Carolina that they said would dilute minority rights. Courts also forced changes in Florida’s new early-voting procedures.

“In the midst of the recent assault on voter access, the Voting Rights Act is playing a pivotal role beating back discriminatory voting measures,” said Debo P. Adegbile, acting president of the NAACP Legal Defense Fund.

A panel of the U.S. Court of Appeals for the D.C. Circuit voted last spring to uphold the 2006 reauthorization, which passed with lopsided votes in both houses of Congress and was signed with fanfare by President George W. Bush.

U.S. Circuit Judge David S. Tatel wrote that the judicial branch had no reason to second-guess Congress’s decision to reauthorize the law.

“Congress drew reasonable conclusions from the extensive evidence it gathered,” Tatel wrote. “In this context, we owe much deference to the considered judgment of the people’s elected representatives.”

Conservative legal activists and Republican attorneys general from some of the covered states — Alabama, Alaska, Arizona, Georgia, Louisiana, Mississippi, South Carolina, Texas and Virginia — launched challenges to the law after the Supreme Court in 2009 raised questions about its continued constitutionality.

“Things have changed in the South,” Chief Justice John G. Roberts Jr. wrote in that opinion, which put aside for the time being the constitutional question. “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 concluded that the 2006 extension met two requirements identified by the Supreme Court: that the burdens imposed by the act were justified by “current needs,” and that the discrimination “evil” that Section 5 was meant to eliminate is still concentrated in the jurisdictions singled out for “pre-clearance” by federal authorities.

The Obama administration aggressively used Section 5 during this year’s election season to challenge restrictions on voting passed by Republican-led legislatures. The states said the changes were meant to combat voter impersonation fraud or make Election Day easier on election officials.

The case is Shelby County v. Holder .

The court also agreed to decide Friday a case from Maryland that pits individual privacy rights against the state’s ability to conduct criminal investigations.

The issue is whether police may take DNA samples from those arrested in connection with, but not convicted of, violent crimes. Police took a sample from Alonzo King Jr. in 2009 when he was arrested on assault charges, under a law that authorized gathering DNA from those arrested on charges of violence or burglary.

The sample linked King to an unsolved 2003 rape case.

The Maryland Court of Appeals threw out the rape conviction, saying the collection violated King’s constitutional rights and was more intrusive than simply taking fingerprints.

Chief Justice Roberts had stayed the Maryland court’s opinion while the court decided whether to review the case, and the collection of DNA samples has continued. Maryland Attorney General Douglas F. Gansler said the DNA database identifies the perpetrators of “some of our state’s most gruesome unsolved cases.”

Stephen B. Mercer of the Maryland Office of the Public Defender said he is confident that the court will eventually agree that “that persons who are presumed to be innocent should not be subject to warrantless seizure and indefinite retention of their intensely personal genetic information.”

Aaron C. Davis contributed to this report.