WASHINGTON — A central provision of the Voting Rights Act of 1965 may be in peril, judging from tough questioning on Wednesday from the Supreme Court’s more conservative members.

If the court overturns the provision, nine states, mostly in the South, would become free to change voting procedures without first getting permission from federal officials.

In a vivid argument in which the lawyers and justices drew varying lessons from the legacies of slavery, the Civil War and the civil rights movement, the court’s conservative wing suggested that the modern South had outgrown its troubled past and that the legal burdens on the nine states were no longer justified.

Chief Justice John G. Roberts Jr. asked skeptically whether “the citizens in the South are more racist than citizens in the North.” Justice Anthony M. Kennedy, whose vote is probably crucial, asked whether Alabama today is an “independent sovereign” or whether it must live “under the trusteeship of the United States government.”