Polymarket cites Commerce Clause in Missouri suit, splitting from Kalshi

Polymarket's federal lawsuit against Missouri does not look like Kalshi's. That distinction matters more than the shared defendant.

Both companies received cease-and-desist letters from the Missouri Gaming Commission in September, instructing them to stop offering sports event contracts on the grounds that those products require a state gaming licence. Both companies refused. Both filed federal suits. Robinhood followed the same week. But Polymarket's legal team reached for a different constitutional hook — the Commerce Clause rather than the Commodity Exchange Act's preemption framework — and that choice tells you something about how the litigation is likely to fractionate.

Kalshi's argument, which Robinhood has now adopted nearly wholesale, runs through the CEA's exclusive jurisdiction provision. Congress gave the CFTC authority over designated contract markets and the products traded on them, the argument goes, and that authority is exclusive by design. Missouri's gaming licence requirement, applied to a federally designated DCM, cannot stand under the Supremacy Clause. That argument has produced results: a temporary restraining order and preliminary injunction in New Jersey that Kalshi has used as a template. Robinhood's complaint filed in the Eastern District of Missouri quotes the jurisdictional architecture directly — "exclusive jurisdiction," "single, uniform national derivatives market" — and asks for the same trilogy of relief.

Polymarket's Commerce Clause angle is structurally different. It argues not that federal derivatives law has displaced the field, but that Missouri's enforcement discriminates against or burdens interstate commerce in a way that the Constitution does not permit. This is older constitutional law, less tethered to the specific regulatory infrastructure that the CFTC has built since Dodd-Frank, and in some ways more portable. It does not require Polymarket to hold a particular federal designation or to show that its products fall within a specific statutory category. It argues, more broadly, that a state cannot use its gaming authority to wall off a national commercial market.

The divergence is worth watching for a reason that goes beyond legal tactics. When courts eventually rule on these cases — and the November 20 hearing in Utah suggests the schedule is compressing — they will produce opinions that speak to different constitutional premises. A CEA preemption ruling and a Commerce Clause ruling do not necessarily land in the same place on the underlying question, which is whether states retain any meaningful authority over event contracts offered to their residents. The CEA route produces a sharper answer: either federal law occupies the field or it doesn't. The Commerce Clause route is more graduated and leaves more room for state regulation that is sufficiently tailored.

The CFTC's proposed rulemaking on sports event contracts received eleven public comments before the deadline. That number is not an accident of indifference — it reflects an industry that has decided to litigate rather than comment, and regulators who have not signalled what a compliant rule would actually permit.

The operative legal standard, across all of these cases, is whether the CEA's exclusive jurisdiction provision under 7 U.S.C. § 2(a)(1)(A) displaces state gaming authority over products listed on CFTC-regulated exchanges, and whether that displacement is total or whether states retain a police-power residual that the courts have not yet defined.