A Democratic political group launched a legal campaign Wednesday to create additional majority-minority congressional districts in three Southern states, claiming the current maps discriminate against black voters.

Attorneys filed separate federal lawsuits in Alabama, Georgia and Louisiana, challenging congressional maps lawmakers in each state approved in 2011.

The lawsuits filed on behalf of several black voters in each state are backed by the National Redistricting Foundation, a nonprofit affiliate of the National Democratic Redistricting Committee, which is chaired by former U.S. Attorney General Eric Holder.

The suits claim the districts violate a section of the Voting Rights Act by depriving black voters of an equal opportunity to elect candidates of their choice to the U.S. House of Representatives. They ask the courts to block the three states from holding any more congressional elections under their current maps.

The new lawsuits mean there now are redistricting challenges pending in a dozen states — in some places, multiple lawsuits —alleging racial or political gerrymandering in U.S. House or state legislative districts. The U.S. Supreme Court is expected to rule later this month on at least two of those cases alleging unconstitutional partisan gerrymandering by the Republican-led Legislature in Wisconsin and the Democratic-led Legislature in Maryland.

Though likely too late to affect this year’s elections, the lawsuits could force districts to be redrawn in advance of the 2020 elections. The timing is important because any court rulings could set precedents for when all states must redraw legislative districts based on the results of the 2020 Census.