Polymarket US sues Missouri AG Hanaway in federal court
Polymarket US filed a lawsuit against Missouri attorney general Hanaway and others on November 9, 2026, in the U.S. District Court for the Eastern District of Missouri. The case is docketed as 4:26-cv-01930. The complaint is a preemptive move, filed as prediction market platforms face escalating state-level legal challenges. No details on the claims or relief sought were immediately available in the filing notice. The suit adds to an active legal fight in Missouri over state authority to regulate event contracts.
Polymarket US sues rather than accepting Missouri orders, joining Underdog and Kalshi with active federal challenges there while Polymarket and Robinhood previously took orders without fighting. Each courtroom outcome signals whether litigation or settlement is smarter for holdouts. The suit tests whether collective federal challenges can reverse the pattern where Kalshi's solo Sixth Circuit effort failed after Ohio and Tennessee stripped federal preemption shields.
Circuit splits are deepening, with the NFL urging justices to back state gambling authority. Underdog and Crypto.com and Novig already filed Missouri challenges too. Polymarket's decision to join the federal fight raises litigation stakes for every platform still calculating state-by-state risk. A Supreme Court ruling could lock in federal preemption or cement state authority nationwide.