A three-judge panel on Tuesday unanimously struck down Alabama's recently redrawn congressional map, finding that that the GOP-drafted plan did not comply with the Voting Rights Act as it did not create a second district in which Black voters would likely be able to elect their preferred candidate.
Court-appointed experts will now draw a new map for the 2024 elections.
Alabama is expected to appeal the decision to the U.S. Supreme Court.
The state Legislature had passed their latest congressional map in late July, after the U.S. Supreme Court ruled a month earlier that the previous map violated the civil rights law.
But the revised plan only included one majority-Black district, with a second district that had less than 50% Black residents -- prompting swift outcry from Democrats and advocates who said that flagrantly violated the court's instructions.
The federal ruling that originally struck down Alabama's map in 2022 ordered the Legislature to draw "two districts in which Black voters either comprise a voting-age majority or something quite close to it."
About 27% of Alabama residents are Black, according to census data. Only one of its seven districts is represented by a Black lawmaker.
Defenders of the now-rejected map argued they had achieved "something quite close," as the court ordered. Under that plan, Black voters comprised 39.93% of Alabama's 2nd District and 50.65% of the 7th District.
In their sharply worded opinion on Tuesday, the federal panel disagreed.
"Law requires the creation of an additional district that affords Black Alabamians, like everyone else, a fair and reasonable opportunity to elect candidates of their choice. The 2023 Plan plainly fails to do so," U.S. Circuit Judge Stanley Marcus, U.S. District Judge Anna Manasco and U.S. District Judge Terry Moorer wrote.
The judges wrote that they were "deeply troubled" that Alabama lawmakers enacted a map that disregarded the findings in 2022.
"We are not aware of any other case in which a state legislature - faced with a federal court order declaring that its electoral plan unlawfully dilutes minority votes and requiring a plan that provides an additional opportunity district - responded with a plan that the state concedes does not provide that district," the judges wrote.
Critics of the July plan celebrated the federal court's decision on Tuesday.
"The court rightly stepped up and applied the law in order to protect the rights of all Alabamians. The state's blatant defiance of both the court-and the Supreme Court-will be fought as long as necessary," former U.S. Attorney General Eric Holder, chairman of the National Democratic Redistricting Committee, wrote in a post on X, formerly known as Twitter.
In a statement, the Alabama Republican Party called the decision "disappointing."
"While we respect the Court, we are disappointed in its decision, and we trust that the State will ultimately prevail in this litigation," the party wrote.
ABC News' Caroline Curran contributed to this report.