Eleven states join New Jersey in Supreme Court betting case

New Jersey amicus push brings eleven states into Kalshi Supreme Court fight

Thirty-nine states and Washington D.C. filed briefs urging the Supreme Court to hear New Jersey's appeal against Kalshi — and the arguments they made go considerably further than the preemption question that has dominated coverage of this dispute.

The volume alone is worth sitting with. Eleven amicus briefs is not routine coalition-building. It is a signal that state attorneys general, tribal gaming interests, the NFL, and a coalition that spans nearly the entire country have concluded that the federal courts will not resolve this correctly on their own, and that the Supreme Court needs to set the terms.

The six arguments these briefs raise tell you what the coalition actually cares about. Exchange self-certification — the process by which Kalshi listed sports contracts without prior regulatory approval — sits at the centre of several of them. The argument is not simply that states have gambling authority. It is that the CFTC's own self-certification framework allowed an exchange to bring products to market that no federal regulator had affirmatively reviewed. If that framework holds for sports contracts, it holds for anything a sufficiently creative exchange decides to list next.

Tribal sovereignty is the argument I find most underpriced in the commentary. Tribes have compacts, exclusivity arrangements, and revenue-sharing agreements with states that were negotiated on the assumption that sports wagering would flow through state-licensed channels. A federal preemption ruling that bypasses those compacts does not just affect Kalshi's market share — it cuts through the legal architecture that tribal gaming has spent thirty years constructing. When tribes ask what happens if states lose at the Supreme Court, they are not asking a procedural question.

The PASPA reference is the one that should give Kalshi pause. The Supreme Court's 2018 ruling striking down the federal sports wagering ban was understood at the time as a victory for state authority. Several briefs are now arguing, in effect, that allowing the CFTC to preempt state gambling law on sports contracts would replicate the federalism problem that PASPA created — and that the Court, having dismantled one federal override of state sports wagering authority, should be reluctant to permit another through a different regulatory door.

The age restriction argument is the one I think carries the most political weight. Prediction markets currently operate under CFTC rules that set an eighteen-year-old floor. State gaming frameworks often go further. Nevada's chairman has already said that an eighteen-year minimum on sports contracts is a statutory violation of state gambling law. If the Supreme Court takes the case, that argument will be in the room.

The CFTC has been pressing for clarity — its September warning to exchanges about manipulation risks involving public officials, and its subsequent litigation against New York and Wisconsin, suggest a regulator that wants the jurisdictional question answered as much as the states do. What it has not resolved is whether that clarity will come from a court that reads the Commodity Exchange Act narrowly or one that reads state gambling authority broadly. Those are not the same question, and the eleven briefs now on the docket are written by people who understand the difference.

The Ohio rehearing bid sits alongside all of this. Kalshi lost in the Sixth Circuit and filed for rehearing. The circuit split that Underdog has been widening with its state-by-state litigation strategy now has a companion: a split in how federal circuits will treat the same underlying jurisdictional claim. The Supreme Court takes cases when circuits disagree. The disagreement is now visible.

Markets exist on whether the Court grants certiorari. I think they are underpricing the grant. Eleven amicus briefs and a deepening circuit split is the profile of a case the Court takes — not because the justices have signalled anything, but because the conditions that historically produce a grant are all present at once.