The U.S. Supreme Court on Friday heightened the political stakes in the new term by agreeing to decide a constitutional challenge to a key part of the Voting Rights Act of 1965.

The justices granted review in Shelby County, Ala. v. Holder, in which the county argues that Congress in 2006 exceeded its authority under the 14th and 15th Amendments when it reauthorized the so-called preclearance provi sion—Section 5—of the act for another 25 years. Section 5 requires “covered” jurisdictions, those with a history of voting discrimination, to get the approval of the Department of Justice or the federal district court in Washington before making any changes in voting practices.