Polymarket Sues Michigan in Federal Preemption Fight

Polymarket filed a preemptive federal lawsuit against Michigan Attorney General Dana Nessel on March 4, escalating a legal confrontation between prediction market platforms and state gambling regulators that legal analysts say is ultimately bound for the US Supreme Court.

The lawsuit, filed by Polymarket’s US entity QCX LLC in the US District Court for the Western District of Michigan, came two days after Nessel sued Polymarket’s closest domestic rival, Kalshi, in Michigan state court. The attorney general’s complaint in Ingham County’s 30th Judicial Circuit Court accused Kalshi of operating as an “unlicensed sportsbook” by offering sports event contracts to Michigan residents without a state gaming licence.

The Core Legal Question

At the centre of both cases is whether the federal Commodity Exchange Act (CEA) preempts state gambling laws. Prediction market platforms argue they are federally registered designated contract markets dealing in binary options and derivatives — financial instruments subject to CFTC jurisdiction, not state gambling regulation. State regulators counter that the “financial instrument” framing is a legal fiction designed to avoid the taxes and consumer protections that licensed sportsbooks must meet.

Michigan’s case against Kalshi focused specifically on sports-related trading volume. Regulators noted that while Polymarket built its profile on election betting, a significant portion of the estimated $44 billion in industry-wide prediction market volume recorded in 2025 was generated by sports contracts. By framing those contracts — questions such as “Will the Detroit Pistons win their next game?” — as sports betting, the attorney general sought to apply the same licensing requirements that govern operators like DraftKings or FanDuel.

Kevin B. Frankel, partner at Benesch and chair of the firm’s state attorneys general practice, writing in Bloomberg Law, described the dual-track Michigan litigation as the most aggressive application of this strategy yet — with simultaneous proceedings in state and federal court creating a significant risk of contradictory rulings.

Polymarket’s Three-Pillar Legal Strategy

Polymarket’s federal filing rests on three main arguments. First, the company contends that as a federally registered designated contract market, the CFTC holds sole regulatory authority over its products, leaving no room for state enforcement. Second, it argues that what Michigan characterises as gambling is, under federal law, a derivative or binary option used for hedging and price discovery. Third, Polymarket claims it would suffer irreparable harm if Michigan succeeded, as it would be forced to geofence the state, fragmenting a national market and draining the liquidity the platform requires to function.

The choice of federal court was deliberate. State courts have recently proved more receptive to regulators, and attorneys general are perceived to hold a home-court advantage there. Nevada’s restraining order against Polymarket earlier this year demonstrated that state-level enforcement can produce rapid and damaging results for the platforms.

CFTC Backing Changes the Dynamic

What separates the current round of litigation from earlier skirmishes is the posture of the federal regulator. Under the Trump administration, CFTC Chairman Michael Selig rescinded Biden-era rule proposals that would have banned political and sports-related prediction contracts. Selig has publicly criticised what he called “overzealous state governments” undermining federal authority, and the CFTC has signalled it will actively defend its jurisdiction. Polymarket’s Michigan filing cites Selig’s public statements directly as evidence that Michigan is acting in violation of the Supremacy Clause.

Kalshi has already filed seven federal lawsuits against state regulators across the country as part of what Frankel describes as a “first strike” strategy. Kalshi reported $1 billion in Super Bowl trading volume, up 2,700% year-on-year, illustrating the commercial stakes driving the platforms’ willingness to litigate aggressively.

Michigan as a Test Case

Michigan matters because it is the first state where the dual-track strategy is playing out simultaneously in two different court systems. If the state court rules in Nessel’s favour, it sets a precedent that states can enjoin prediction market platforms regardless of their federal registration. If Polymarket prevails federally, it could effectively immunise the sector from state gambling law enforcement. With appeals virtually certain either way, the Michigan cases are expected to generate circuit splits that eventually force the question to the Supreme Court.

A patchwork outcome — in which prediction markets remain accessible in some states but not others — would require platforms to operate a fragmented, geofenced product rather than a single national market. The broader US regulatory picture for 2026 already shows states moving in conflicting directions on gambling expansion and crackdown, and the prediction market fight adds another layer of uncertainty for operators and investors tracking the sector.

The two active Michigan cases are QCX, LLC v. Nessel (W.D. Mich., No. 1:26-cv-00710, complaint filed 3/4/26) and Nessel v. KalshiEX LLC (Mich. Cir. Ct., No. 26-001087-CZ, complaint filed 3/3/26). Their outcomes will shape how dozens of states currently monitoring the litigation decide to act.

Source: Bloomberg Law