The Missouri Supreme Court ruled unanimously on Thursday that congressional districts redrawn to benefit Republicans and used in last month’s primary election were invalid. The court ordered that the previous map go back into effect for November.
While the ruling at least temporarily thwarted Republicans’ efforts to pick up a House seat in the Kansas City area, it also left urgent, unanswered questions about how to hold a general election under a map different from what was used in the primaries.
The state attorney general, Catherine Hanaway, a Republican, vowed to appeal to the U.S. Supreme Court.
“This unprecedented decision clearly violates federal law and has thrust our state into a full‑fledged constitutional crisis,” she said.
Missouri election officials had vowed to forge ahead with using the redrawn borders in November unless explicitly told otherwise.
The State Supreme Court’s seven judges did exactly that in their ruling, which came a day after oral arguments in the case and less than a week before the deadline to finalize the November ballot. The judges said a referendum on the new district lines had been improperly denied a spot on the November ballot, and that the redrawn map should have been paused until voters weighed in.
The redrawn map “did not go into effect and will not go into effect unless and until approved by the voters,” Judge Ginger K. Gooch, who was appointed by a Republican governor, wrote in the opinion. The prior map, she added, “remains in full force and effect for the November 2026 general election.”
The court did not specify how candidates would be determined for a general election.
Barring intervention from the U.S. Supreme Court, the ruling appeared likely to resolve a year of legal uncertainty over the fate of the new map, which was redrawn outside the usual once-a-decade cycle at President Trump’s request.
But swapping out congressional maps between a primary and general election is unplowed legal ground, and what would happen next was uncertain on Thursday evening.
In their filings with the State Supreme Court, redistricting opponents had suggested that candidates who won their primaries under the redrawn map might remain the nominees in the same-numbered districts under the old lines. Alternately, they theorized, state law allowed party nominating committees to select candidates for each district.
Officials with the secretary of state’s office in Missouri did not immediately respond to requests for comment about the ruling or about how they believed congressional candidates should be determined for the general election.
Richard von Glahn, the leader of the group that organized the referendum, said in a statement on Thursday that “this is what democracy looks like.”
“In a year when map-drawing has become a national weapon, courts across the country are watching what happens here,” said Mr. von Glahn, the executive director of People Not Politicians Missouri. “A Missouri win for the referendum is a signal that the people still hold the power.”
Attorney General Hanaway warned of grave consequences if the ruling stood.
“We are confident that the federal courts will not allow every Missouri voter to be disenfranchised — which is what today’s decision does,” she said.
Gov. Mike Kehoe, a Republican, said he was “extremely disappointed in today’s decision by unelected judges and their lack of respect for the legislative process.”
Though the Missouri Supreme Court determined that it was legal for legislators to redraw the map, it also found that residents opposed to the boundaries had acted within the law when they submitted hundreds of thousands of signatures seeking a statewide referendum on the issue. The judges found that the redrawn map should have been suspended until a referendum could be held.
Missouri Republicans were among the first to heed Mr. Trump’s call to redistrict to improve their party’s chances of holding the House in the 2026 midterms. They passed their new map in September 2025 during a special session called by Mr. Kehoe, who signed the new boundaries into law later that month.
Other states, including some led by Democrats, have also made attempts to redistrict, with varying degrees of success. Republicans nationally have positioned their party to pick up seats in the House.
In another decision on Thursday, the Maryland Supreme Court ruled that a constitutional amendment proposed by Democratic legislators could be voted on in November. The measure would not affect this year’s midterms but would give the Democratic-controlled Legislature freer reign to draw a new map in the future if approved.
The redrawn Missouri map sliced the core of Kansas City, Mo., the state’s largest city, into several districts in an attempt to unseat Representative Emanuel Cleaver, one of two Democrats in the state’s congressional delegation. The new map did not significantly alter the partisan makeup of the other Democratic-held district, which is in the St. Louis area.
Mayor Quinton Lucas of Kansas City, a Democrat, described the ruling as maintaining “a voice for Kansas Citians.”
“The Missouri Supreme Court got it right, adhering to our Constitution and ensuring rights are protected, especially for those too often left out,” he said in a statement.
Redistricting opponents questioned the legality of the new map in several lawsuits that sought to revert to the old boundaries. Republicans repeatedly prevailed in Missouri courts.
Democrats and their allies also sought to force a statewide referendum but initially faced roadblocks.
Secretary of State Denny Hoskins, who is responsible for approving referendum questions, said last month that he believed redistricting was ineligible for a statewide vote. Mr. Hoskins, a Republican, waited until the day of the primary election, when voters were casting ballots based on the new district lines, to release that opinion.
That left the Missouri Supreme Court as redistricting opponents’ last chance to undo the new map. Five of the seven judges on the court were appointed by Republican governors, and two by Democrats.
In court filings, lawyers for redistricting opponents described Mr. Hoskins’s decision to wait until the day of the primary election to reject the referendum as a “tactical delay.” Even though the primary was held using the redrawn boundaries, they said, the general election in November should use the old ones.
Lawyers from the Missouri attorney general’s office dismissed those arguments in their own filing as “legally wrong and, frankly, crazy.”
The state’s lawyers said that redistricting, unlike other laws passed by the legislature, was ineligible for a referendum because the U.S. and Missouri Constitutions gave lawmakers the authority to create congressional maps. Finding otherwise, they warned, could lead to chaos.
“Every time redistricting occurs, the minority political party could easily gather the signatures needed to freeze a congressional map for one election cycle — a small price to pay for one or more congressional seats,” the state’s lawyers argued.
Campbell Robertson contributed reporting.
