The judges say in their unanimous ruling that time is too short to put the law in effect ahead of the Nov. 6 elections.
The law requires those wanting to vote in South Carolina to show one of five types of photo identification in order to cast a ballot.
The judges say the law does not discriminate or wipe out voting rights gains of African-Americans.
South Carolina's law was the first voting law in nearly 20 years that the Department of Justice refused to OK.
(Copyright 2012 by The Associated Press. All Rights Reserved.)