The Supreme Court's conservative justices voiced deep skepticism Wednesday about a section of a landmark civil rights law that has helped millions of Americans exercise their right to vote.

In an ominous note for supporters of the key provision of the Voting Rights Act, Justice Anthony Kennedy both acknowledged the measure's vital role in fighting discrimination and suggested that other important laws in U.S. history had run their course. "Times change," Kennedy said during the fast-paced, 70-minute argument.

Kennedy's views are likely to prevail on the closely divided court, and he tends to side with his more conservative colleagues on matters of race.

The court's liberals and conservatives engaged in a sometimes tense back-and-forth over whether there is an ongoing need in 2013 for the part of the voting rights law that requires states with a history of discrimination, mainly in the Deep South, to get approval before making changes in the way elections are held.