The Wisconsin Supreme Court ruled Friday that the state’s heavily gerrymandered state legislative maps are unconstitutional and ordered lawmakers to draw new maps ahead of the 2024 elections.

The case over the Republican-drawn lines, which emerged as a political flashpoint in the closely watched swing state, was the first major one to be heard and decided by the court’s new liberal majority.

In a 4-3 ruling along ideological lines, justices tasked lawmakers with drawing new maps, but wrote that if they fail to do so, the court could move forward with a preliminary “remedial” map-drawing process itself.

The ideological balance of Wisconsin’s high court swung to liberals for the first time in 15 years in April after Janet Protasiewicz won a seat on the court being vacated by a retiring conservative justice.

During the race, Protasiewicz criticized the state’s maps as being “unfair” and “rigged” — comments that conservatives said proved that she had forecast how she would rule on the issue. Following her victory, Republicans in the state subsequently demanded that she recuse herself from the case, with some threatening to impeach her for refusing to do so.

The state’s current legislative map — which experts have said is one of the most gerrymandered in the U.S. — was approved last year by the state Supreme Court’s previous conservative majority after Gov. Tony Evers, a Democrat, and the GOP-controlled Legislature couldn’t agree on boundaries.

The freshly tossed legislative maps had heavily favored Republicans: They control 64 of the 99 seats in the state Assembly and 22 of the 33 in the state Senate, even though the last two presidential elections were both decided by less than 1 percentage point in the state and the last two gubernatorial races were both decided by less than 4 points.

In their challenge of the map, Democratic attorneys contended it was unconstitutional because it violates the state constitution’s requirement that districts be contiguous — a complicated and poorly defined rule mandating that legislative districts be physically adjacent to one another. Critics of the current maps have noted that some Wisconsin districts include “islands” (or detached areas) within other districts, with some comparing them to Swiss cheese.

In their decision Friday, the court’s liberal justices agreed, writing that the Wisconsin Constitution holds that “state legislative districts must be composed of ‘contiguous territory.’”

“At least 50 of 99 assembly districts and at least 20 of 33 senate districts violate this mandate, rendering them unconstitutional,” they wrote.

“Remedial maps must be adopted prior to the 2024 elections. We are hopeful that the legislative process will produce new legislative district maps. However, should that fail to happen, this court is prepared to adopt remedial maps based on the criteria, process, and dates set forth in this opinion and the concurrent order,” the justices continued.

The liberal majority ordered state lawmakers to have the new maps in place before the Aug. 13 legislative primary elections.

The ruling will require every member of the state Assembly and half of the members of the state Senate to run in a redrawn district.

In a blistering dissent, conservative Justice Annette Ziegler reiterated criticisms thrown at the court’s liberal majority by Republicans in the state, writing that “this deal was sealed on election night” — an apparent reference to Protasiewicz having won in April after campaigning in part on criticism of the maps.

“No longer is the judicial branch the least dangerous in Wisconsin,” Ziegler wrote.

State Assembly Speaker Robin Vos, a Republican who’s been among Protasiewicz’s most vocal critics, suggested on the social media site X that Republicans could appeal the ruling to the U.S. Supreme Court.

“The case was pre-decided before it was even brought,” Vos wrote. “Fortunately, the U.S. Supreme Court will have the last word.”

Progressive groups lauded the ruling.