Massachusetts Attorney General Maura Healey and 21 other state attorneys general have filed an amicus brief in a case arguing that North Carolina unconstitutionally gerrymandered congressional districts to undermine voting rights.

The brief accuses the state of deliberately redrawing voting districts to keep "one political party in power and for no other justification than to maximize partisan advantage," Healey's office said in a statement Friday.

The amicus brief was filed in support of the plaintiffs in the case of Rucho v. Common Cause, in which a group of North Carolina voters accuses Republican lawmakers of unconstitutionally gerrymandering the state's 2016 congressional map. A lower court agreed and struck down the map. The case will be heard by the U.S. Supreme Court on March 26.

“Extreme partisan gerrymandering undermines the right to vote and weakens our democracy,” Healey said in the statement. “We have asked the Court to empower voters and end the transparent abuses of power we see today.”

The amicus brief is being led by Oregon's attorney general. The other states involved are California, Colorado, Connecticut, Delaware, Hawaii, Iowa, Kentucky, Maine, Michigan, Minnesota, Mississippi, Nevada, Pennsylvania, New Jersey, New Mexico, New York, Rhode Island, Vermont and Washington, as well as Washington, D.C.

Correction: An earlier version of this story said Healey had joined a lawsuit. She joined an amicus brief in support of the existing lawsuit. We regret the error.