The Ohio Supreme Court struck down a congressional map skewed to favor Republicans on Friday, ruling that it was the equivalent of a dealer stacking the deck, and sent it back to state lawmakers to try again.
The map would have given Republicans an advantage of 12 seats to three in elections for the House of Representatives, even though the G.O.P. has lately won only about 55 percent of the statewide popular vote.
“This is not what Ohio voters wanted or expected,’’ the court said of the map.
Mapmakers in Ohio are not allowed to unduly favor one party in redistricting, after voters overwhelmingly passed an amendment to the Ohio Constitution in 2018. The proposed map was drawn by Republicans in the Legislature and passed without Democratic support, and the court rejected it in a 4-to-3 decision.
“When the dealer stacks the deck in advance, the house usually wins,” wrote Justice Michael Donnelly for the majority, adding that the Republicans’ plan was “infused with undue partisan bias.”
The constitutional amendment was an effort to end partisan gerrymandering in the state, and the voting rights groups that brought the suit, including the League of Women Voters of Ohio, argued that Republican lawmakers had ignored the law.
The court agreed, holding that the evidence “makes clear beyond all doubt that the General Assembly did not heed the clarion call sent by Ohio voters to stop political gerrymandering.”
When the case was heard last month, Republicans argued that the districts were fair and met the Constitution’s demand to not to be “unduly” favorable, and that Senator Sherrod Brown, a Democrat re-elected in 2018, would have carried eight of the 15 new districts. Republicans further said that they had drawn six competitive House seats.
In signing the map into law in November, Gov. Mike DeWine, a Republican facing a primary challenge from his right this year, called the G.O.P. plan “a fair, compact and competitive map.”
But the court strongly disagreed. It said the Republicans’ plan violated the law by splitting Democratic-leaning counties in order to dilute their votes, including Hamilton County, which includes Cincinnati. Hamilton County was split between three newly drawn districts “for no apparent reason other than to confer an undue partisan advantage on the Republican Party,’’ the court said.
A spokesman for Republican leaders in the Legislature said they were reviewing the court’s opinion.
Lawmakers have 30 days to overhaul the congressional maps. If they fail, the mapmaking passes to the Ohio Redistricting Commission, which would be given another 30 days. But there is a tighter deadline looming: March 4, when candidates must file paperwork to run.
The court’s decision came two days after it threw out Republican-drawn maps for new state House and Senate districts.
In both cases, Chief Justice Maureen O’Connor, a Republican, joined three Democratic justices to overturn the maps.
A congressional map acceptable to the court could give Democrats two to three more seats in Ohio, some analysts said.
Understand the Battle Over U.S. Voting Rights
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Why are voting rights an issue now? In 2020, as a result of the pandemic, millions embraced voting early in person or by mail, especially among Democrats. Spurred on by Donald Trump’s false claims about mail ballots in hopes of overturning the election, the G.O.P. has pursued a host of new voting restrictions.
A U.S. Supreme Court decision in 2019 that partisan mapmaking could not be challenged in federal courts means that state courts are now the remaining judicial avenue to contest partisan gerrymandering — at least in states like Ohio where the Constitution bans it.
A case headed to North Carolina’s Supreme Court also seeks to overturn a G.O.P. gerrymander. Republicans there would control as many as 11 of the state’s 14 House seats with the new maps, compared to the party’s current advantage of eight seats to five. A lower court on Tuesday upheld the maps.
The state court cases are playing out in a landscape of diminishing prospects for Democrats and voting rights groups seeking to rein in partisan gerrymandering. Broad voting rights legislation in Congress supported by President Biden and his party, which would curtail gerrymandering, received a near-fatal blow this week from Senator Kyrsten Sinema, an Arizona Democrat, who said she would not support changing the filibuster rule to pass it.
In Ohio, Democrats celebrated the court decision. “Once again, the Ohio Supreme Court did what the Legislature refused to do — listened to the will of Ohio voters,’’ Elizabeth Walters, chair of the Ohio Democratic Party, said in a statement. “Any map that further rigs our state in favor of one party over another is unacceptable and we’ll be watching closely.”