Current and former Black state lawmakers in Detroit announced a pending lawsuit to block Michigan’s newly drawn congressional and legislative districts, contending they illegally dilute the voting strength of African Americans.

The step Monday came days after the new Independent Citizens Redistricting Commission finalized U.S. House and legislative maps to take effect in 2022 and last 10 years.

The old maps had 15 such seats by the end of the decade: two in the U.S. House, two in the state Senate and 11 in the state House. Now there are seven, all in the state House.

Commissioners state Black voters can still elect their candidates of choice without comprising at least half of a district’s electorate.

The suit will allege violations of the U.S. Voting Rights Act and the Michigan Constitution. The No. 1 map-drawing criteria for the panel was to comply with the 1965 law, which bans discriminatory voting practices and procedures.

The 13-member commission and its lawyers have said federal law does not require majority-minority districts. Bruce Adelson, who advised the panel on Voting Rights Act compliance, told commissioners there was a lot of “misinformation” or “a lack of information” being circulated by critics of its approach.

The voter-created panel took over the once-a-decade process that had been handled by the Republican-controlled Legislature and resulted in partisan gerrymandering. Commissioners undid “packing” of African American, heavily Democratic voters in Detroit, which has one of the highest percentages of Black residents in the country.

They urged the Michigan Democratic Party “to stand with us” even if the maps are fairer to the party as a whole.

The lawsuit, if successful, would force the commission to revise the maps.