Kalshi sues Missouri as Polymarket US challenges Louisiana

Kalshi and Polymarket US have filed separate federal lawsuits seeking to prevent Missouri and Louisiana officials from applying state gambling laws to their event-contract businesses.

Both complaints were filed on October 27. KalshiEX LLC sued in the Eastern District of Missouri, while QCX LLC, doing business as Polymarket US, brought its case in the Eastern District of Louisiana. The filings seek declarations and injunctions against state enforcement.

Kalshi points to an October 30 deadline

In its 39-page Missouri complaint, Kalshi says Attorney General Catherine Hanaway's office sent a cease-and-desist letter on September 16 requiring it to stop offering sports contracts or comply with state licensing, tax and age requirements.

The company says the original October 16 compliance deadline was extended to October 30. On October 27, according to the complaint, Missouri's solicitor general declined to agree to withhold enforcement.

Kalshi argues that the Commodity Exchange Act gives the Commodity Futures Trading Commission exclusive jurisdiction over its exchange-traded contracts. It also argues that Missouri's licensing requirements conflict with its federal obligations.

The court's October 27 activity record confirms the filing as case 4:26-cv-01860, naming Hanaway, the Missouri Gaming Commission and commission officials as defendants.

Hanaway's office said when announcing the notices that sports event contracts constituted unlicensed sports wagering and that operators must meet Missouri's licensing, tax and minimum-age requirements.

Polymarket US challenges Louisiana's licensing regime

Polymarket US's 45-page complaint, case 2:26-cv-02482, names Attorney General Liz Murrill and other Louisiana officials. It argues that federal commodities law pre-empts the state's proposed application of gambling restrictions.

QCX also brings a Commerce Clause challenge, arguing that Louisiana's licensing regime would require its national exchange to operate from the state and serve only people physically present there.

The company cites a December 5, 2025 Louisiana Gaming Control Board advisory warning state-regulated businesses against facilitating prediction markets, alongside officials' public positions, as evidence of an imminent enforcement threat. Those assertions form part of the company's case; they are not findings by the court.

The Louisiana plaintiff is Polymarket US's operator, QCX. The complaint concerns its US exchange, separate from Polymarket's international platform.

The filings follow a different outcome in Michigan, where Polymarket US agreed to close remaining sports positions by November 25. That agreement does not determine either of the new cases.