The ruling, which is almost certain to be appealed to the Supreme Court, would effectively bar private citizens and civil rights groups from suing under a key provision of the landmark law.
The U.S. Court of Appeals for the Fifth Circuit agreed with a lower-court ruling that the latest congressional map very likely diluted the power of Black voters.
G.O.P. legislatures in Alabama, Georgia and Louisiana are contesting federal orders to redraw congressional maps that disfavor Black voters. The stakes are enormous.