The Voting Rights Act was signed into law in 1965 by President Lyndon Johnson and aimed at discriminatory voting practices such as literacy tests once used by some Southern states. It was passed after "Bloody Sunday," when protestors urging voting rights protections were beaten while trying to march from Selma to Montgomery, Ala.
At issue in the case was whether Congress was right in 2006 to reauthorize the expiring sections of the law for 25 more years.
Roberts lashes out at Congress for reauthorizing the law using a dated coverage formula.
"There is no denying, however, that the conditions that originally justified these measures no longer characterize voting in the covered jurisdictions. By 2009, the racial gap in voter registration and turnout was lower in the States originally covered by Section 5 than it was nationwide," Roberts wrote. "At the same time, voting discrimination still exists; no one doubts that. The question is whether the Act's extraordinary measures, including its disparate treatment of the States, continue to satisfy constitutional requirements. "
Thomas went much further than his colleagues, saying that he would have struck section 5 of the law.
"While the Court claims to issue no holding on section 5 itself, its own opinion compellingly demonstrates that Congress has failed to justify current burdens with a record demonstrating current needs," Thomas wrote. "By leaving the inevitable conclusion unstated, the Court needlessly prolongs the demise of that provision."
Lawyers for Shelby County, Ala., a covered jurisdiction under the VRA, argued that Congress was wrong in 2006 to reauthorize extend the provision. They argued that "things have changed in the South" and that the mostly Southern states covered by Section 5 should no longer be subject to a law that exacts a "heavy, unprecedented federalism cost" absent a widespread and persisting pattern of constitutional violations.
The jurisdictions covered under the law include Alabama, Alaska, Arizona, Georgia, Louisiana, Mississippi, South Carolina, Texas and Virginia as well as portions of California, Florida, Michigan, New York, North Carolina and South Dakota.
In reauthorizing the Act in 2006, Congress held 21 hearings, heard testimony from witnesses and amassed more than 15,000 pages of evidence. The vote was 98-0 in the Senate and 390-33 in the House.
In court briefs, Solicitor General Donald B. Verrilli Jr. argued that "Congress made the considered judgment in 2006 (as it had in 1970, 1975 and 1982) that covered jurisdictions continue to resist minority voters' equal enjoyment of the right to participate in the political process."
A lower court upheld Section 5, ruling that Congress, "after assembling and analyzing an extensive record, made its decision: Section 5's work is not yet done."
The decision was penned by Roberts, who as a young lawyer in the Reagan Justice Department argued to limit the reach of the law. In 2009, the Supreme Court heard a related case and Roberts warned that some members of the court had "serious misgivings" about the constitutionality of Section 5.
ABC News' Joshua Hafenbrack contributed to this report.