The Ohio Supreme Court rejected the state’s new congressional map in a ruling Friday over allegations it unfairly favored Republicans, the first time a court has tossed a state’s redrawn district lines in the current redistricting cycle.

The 4-3 decision found that the map passed last year by Ohio’s Republican-controlled legislature violated a 2018 constitutional amendment on redistricting. Language barring any plan “that unduly favors or disfavors a political party” means the legislature has to redraw the maps in advance of a March 4 candidate filing deadline, the court ruled.

“Despite the adoption of [the amendment], the evidence in these cases makes clear beyond all doubt that the General Assembly did not heed the clarion call sent by Ohio voters to stop political gerrymandering,” the majority opinion read.

Chief Justice Maureen O’Connor, a moderate Republican, joined the court’s three Democrats in the majority. The three dissenting Republicans included Justice Pat DeWine, the son of Gov. Mike DeWine, who signed the map into law and was named a plaintiff in the case.

The court gave the state legislature 30 days to pass a new map.

[States create few new minority districts in redistricting so far]

Under the plan struck down, Republicans would have been favored to win 12 of Ohio’s 15 districts in a state former President Donald Trump carried over Joe Biden 53 percent to 45 percent in 2020. The Princeton Gerrymandering Project gave the map an “F,” citing its partisan lean.

Common Cause, one of the groups challenging the plan, praised the ruling in a statement Friday.

“Ohio voters have been waiting too long for fair districts. We all deserve to participate in meaningful elections, which is why nearly 75 percent of Ohio voters approved putting clear rules prohibiting partisan gerrymandering in the Ohio Constitution,” said Catherine Turcer, executive director of the group’s Ohio chapter. “We are glad the Ohio Supreme Court agrees.”

Earlier in the week, the court tossed the state’s GOP-drawn legislative maps on similar grounds. The court adopted a rationale that has seen success in Pennsylvania and North Carolina courts, finding that partisan gerrymandering violates the state constitution.

Brian Sutherland, a lawyer for the challengers to the legislative maps, said he was glad state courts have taken steps to rein in partisan mapmaking after a 2019 Supreme Court decision in Rucho v. Common Cause found that federal courts would not consider gerrymandering claims.

“This is a great decision for that area of the law because it reaffirms the idea that Rucho leaves gerrymandering claims to the states and that they can and should adjudicate those claims, especially when there’s a provision of the state constitution directed to redistricting,” Sutherland said.

Numerous experts have said political gerrymandering claims will factor into a coming wave of redistricting litigation in state courts this cycle. Those arguments have not found universal success so far; a North Carolina trial court panel on Tuesday disagreed with a prior court ruling and upheld the state’s Republican-drawn congressional map.

[North Carolina court upholds congressional map with GOP lean]

Challengers to the North Carolina map have said they plan to appeal to the Democratic- controlled state Supreme Court.

Ohio had a new redistricting process this time around, as a result of the 2018 changes. Last year, the General Assembly failed to pass a map with a bipartisan majority, sending the mapmaking process to a political commission.

That commission missed its deadlines, sending the process back to the General Assembly and allowing for the legislature to pass a map on a party-line vote.