A federal court in Washington Wednesday heard arguments on a challenge to the Voting Rights Act, a year and a half after the Supreme Court issued an opinion many believe opened the door to undoing the landmark civil rights legislation.

In that 8-1 decision back in 2009, the justices seemed to clear the way for future challenges to the act, while avoiding ruling on the validity of its core provisions. It was originally drafted in 1965 to remedy racial discrimination in voting rules in parts of the South.

Today, Shelby County, Ala., takes center stage as the latest jurisdiction to assert that the noble purposes of the law have been served, and that further enforcement is no longer necessary or legal....