Missouri is trying to illegally enact a gerrymandered congressional map in violation of a century of constitutional precedent, a lawsuit filed Tuesday alleges.

The ACLU of Missouri filed the lawsuit in Cole County on behalf of two Jackson County residents against Attorney General Catherine Hanaway and Secretary of State Denny Hoskins. At the heart of the litigation is the state’s decision to allow the congressional map approved by lawmakers in September to take effect despite a referendum campaign turning in 305,000 signatures to place it on the ballot.

The decision runs contrary to how the process has worked for more than 100 years, said Tori Schafer, director of policy and campaigns at the ACLU of Missouri.

In a statement released before the lawsuit was filed, Hanaway defended the move, saying the map will only be suspended if and when Hoskins verifies enough signatures have been submitted — a process that could take until July.

“Our office will continue to defend the Constitution and ensure that Missouri’s laws are strictly adhered to during this process,” Hanaway said.

If the map is allowed to go into effect, county clerks and local election boards will be asked to update voter rolls to show which district includes each voter. And it means the new map would be used for candidate filing that begins in February.

By the time signatures are verified in July, it would be too late to change the ballot for the August 2026 primaries.

“Given that the filing period for congressional candidates begins on Feb. 24, 2026, this is a transparent ploy to force the use of (the) new congressional map by delaying certification of the referendum’s signatures until it is too late to change the congressional map for the 2026 midterms,” the lawsuit states.

Historically, when a referendum campaign has submitted signatures to put a law on the ballot, that law has been immediately suspended pending a vote of the people.

That’s what happened in 2017, when then-Secretary of State Jay Ashcroft suspended a right-to-work law after a coalition of labor unions submitted 300,000 signatures. The law never ended up going into effect because it was defeated by voters a year later.

But the precedent goes back much further.

In 1914, the Missouri Supreme Court held that once citizens submit signatures, the challenged law is automatically suspended until voters decide its fate. The court warned that allowing a law to take effect while under referendum would gut the people’s constitutional power and turn the process into a sham.

Half a century later, the court explicitly said the purpose of a referendum is to suspend or annul a law before it has gone into effect. Allowing a law to take effect and then later be suspended, the court warned, would invite instability and confusion.

Prior to 2017, the last time the referendum was deployed was 1982. Then-Secretary of State James Kirkpatrick put a new trucking law on hold after signatures were submitted for a referendum. A lawsuit demanding immediate implementation was dismissed, and the law was repealed by voters.