The Supreme Court on Wednesday heard a case brought by black legislators and Democrats from Alabama who claimed officials had rejigged electoral districts to help Republicans.
The redrawing of voting districts along party lines is known as "gerrymandering" and has long been a contentious issue in the United States.
The Supreme Court must determine whether this redistricting was unconstitutional, or a violation of equal protection laws.
The case was brought by the Alabama Democratic Conference and the Alabama Legislative Black Caucus, a group of African American elected officials who say the changes were electoral gerrymandering where race was a "predominant factor."
They say the new voting map is unconstitutional because it lumps black voters, who tend to vote Democrat, in other districts where the elected officials are already black.
The result, they claim, is that black voters are deprived of having an influence in whiter, and more Republican, voting districts.
"If you look at the map, what they did is that they cornered out the black" voters, said Donald Verrilli, a lawyer for the Obama administration.
"Our position is race can't be used excessively and in an unjustified way ... for a partisan purpose," said Richard Pildes, a lawyer for the Black Caucus.
Last year, Alabama brought another case in which the Supreme Court struck down a key provision of the Voting Rights Act.
The change meant nine mainly southern states with histories of racial discrimination at the polls no longer have to check with the federal government before changing voting practices.
In 2012, Alabama Republicans drew up new voting districts for the Senate and the House of Representatives.
The Supreme Court decision is expected in June.