Majority of state attorneys general back state power to regulate prediction markets
A bipartisan coalition of state attorneys general filed an amicus brief asking the Supreme Court to let states regulate prediction markets. The brief was filed in support of New Jersey and dated October 8, 2026. The filing escalates the federal-state conflict over whether CFTC-registered event-contract platforms can be blocked by state gambling laws. Both sources disagree on the exact count, reporting either 39 states plus D.C. or 40 total.
The brief hardens the state alliance against federal preemption and signals that Kalshi and Polymarket now face coordinated opposition, not scattered lawsuits. Every platform with CFTC registration must prepare for state courtroom fights even where no case exists yet, because a Supreme Court grant is the only path to uniform rules and the court has already shown reluctance. Kalshi lost preemption in Ohio and Tennessee under the same gambling framing these AGs endorse.
Polymarket's New York suit rests on identical state authority claims. Traders hold positions whose legality shifts with state borders, not federal paperwork. If the court takes the case and sides with the states, geofencing becomes permanent architecture. If it denies cert, the state patchwork deepens anyway. Either way, platforms must fund parallel legal tracks without a federal backstop.