The ruling is the second time the court has thrown out a congressional plan enacted by the Republican-controlled state legislature, and the three-judge panel in Birmingham wrote that it saw little reason to give lawmakers a third chance. Instead, a court-appointed special master will be tasked with creating a new map ahead of next year's vote.

"We have now said twice that this Voting Rights Act case is not close," the judges wrote. "And we are deeply troubled that the State enacted a map that the State readily admits does not provide the remedy we said federal law requires."

Under the Republican map, only one of the state's seven congressional districts is majority Black, even though Black residents make up more than a quarter of the state's population. The state's lone Democratic U.S. representative, Terri Sewell, represents that district.

The panel first intervened in 2022, ruling that an earlier Republican plan was illegal. After the U.S. Supreme Court upheld the panel's decision in June, the Birmingham court ordered Alabama legislators to create a second district with either a Black majority or "something quite close" to comply with the Voting Rights Act. The law bars lawmakers from drawing district lines in a manner that discriminates against minority voters.

The latest plan increased the number of Black voters in a second district but fell far short of a majority, prompting civil rights groups to challenge the new map in court once again.

The Alabama case is among several legal battles over redistricting that could result in new congressional maps in at least half a dozen states, enough to determine congressional control in the November 2024 election. Republicans currently hold a slim 222-213 majority in the U.S. House of Representatives.

A Florida state judge on Saturday ruled that a redistricting plan advanced by Republican Governor Ron DeSantis violated the state constitution by unlawfully diminishing the power of Black voters in northern Florida. The judge ordered lawmakers back to the drawing board, though an appeal is likely.

The Supreme Court also ruled in June that a challenge to Louisiana's congressional map could advance. A federal court has already ordered lawmakers to draw a second majority-Black district, and a U.S. appeals court is set to review the case next month.

Alabama's Republican legislative leaders did not immediately comment on Tuesday's ruling, but they are expected to appeal.

"Alabama openly admits its intention to defy the law and the U.S. Supreme Court," the plaintiffs who challenged Alabama's map, including the state chapter of the NAACP, said in a joint statement. "But we will not back down."