WASHINGTON – Three years ago, the Supreme Court warned there could be constitutional problems with a landmark civil rights law that has opened voting booths to millions of African-Americans. Now, opponents of a key part of the Voting Rights Act are asking the high court to finish off that provision.

The basic question is whether state and local governments that once boasted of their racial discrimination still can be forced in the 21st century to get federal permission before making changes in the way they hold elections.

Some of the governments covered – most of them are in the South – argue they have turned away from racial discrimination over the years. But Congress and lower courts that have looked at recent challenges to the law concluded that a history of discrimination and more recent efforts to harm minority voters justify continuing federal oversight.