The fear of civil rights groups and others that the U.S. Supreme Court might deal a lethal blow to a key provision of the Voting Rights Act of 1965 appeared to play out in real time on February 27 in arguments before the justices.

The provision is Section 5, considered the heart of the act. It requires government entities with a history of voting discrimination to have any changes in voting practices “precleared,” or approved, by the U.S. Department of Justice or the federal district court in Washington. Section 5 currently covers nine states, primarily in the South, and parts of seven others. In Shelby County, Alabama v. Holder, the court is asked whether Congress exceeded its authority under the 15th and 14th amendments when it reauthorized Section 5 under a formula that the challengers contend is outdated and intrusive on state sovereignty. Four of the court’s conservative justices voiced strong skepticism about the constitutionality of the act’s Section 5, which Congress reauthorized in 2006 for 25 more years. Justice Clarence Thomas remained silent, although he wrote in a 2009 Voting Rights Act case that he would strike down Section 5. The court’s four more liberal justices appeared supportive of the section’s constitutionality.