The decision comes after the court's earlier rejection in June of a congressional redistricting map in Alabama, and unfreezes the Louisiana case, which had been on hold pending the Alabama verdict. In both states, Black voters are a majority in only one congressional district.
Lower courts had previously ruled that the maps raised concerns that Black voting power had been diluted, in violation of the federal Voting Rights Act.
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Louisiana has a Black population of approximately one-third, while more than one in four Alabamians are Black.
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The justices had previously allowed the state's challenged map to be used in last year's elections after they agreed to hear the Alabama case, but the case had separately been appealed to the 5th U.S. Circuit Court of Appeals in New Orleans.
The justices have now stated that the appeal can go forward in advance of next year's congressional elections.
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