The suit that says Alabama broke the law by blocking Birmingham's minimum wage hike was amended Thursday to claim the nullification violated the Voting Rights Act of 1965.

In April, the Alabama National Association for the Advancement of Colored People and Greater Birmingham Ministries filed the suit in U.S. District Court. The original suit claimed that HB 174 is tainted "with racial animus" and that is violates the equal protection clause of the U.S. Constitution.

The amended complaint filed Thursday added the Alabama Legislative Black Caucus and nine individual black state legislators as plaintiffs to the suit.

The amended suit also added a new complaint: that the defendants violated the Voting Rights Act of 1965 by transferring control over minimum wages from Birmingham's officials - who were voted in by Birmingham's majority black electorate - to state officials, who were elected by a majority white electorate. The suit claims this effectively disenfranchises Birmingham's voters.

"It perpetuates an official policy of political white supremacy that has been maintained in Alabama since it became a state in 1819, whereby white control is preserved by state government over the governing bodies of majority-black counties, cities, and educational institutions," the complaint says.

The suit argues that the bill violates equal protection law because it targets an ordinance that Birmingham's black community and council strongly supported.

The Birmingham City Council voted in 2015 to raise the city's minimum wage to $10.10 per hour through incremental raises. The Republican super majorities in the legislature's House and Senate put a bill to void the increase on the fast track, prompting the council to expedite Birmingham's raise, but the law ultimately voided the ordinance.