NFL files 32-page amicus brief with the US Supreme Court on sports prediction market integrity

The NFL has entered the Supreme Court fight over sports event contracts, filing a 32-page amicus brief in Flaherty v. KalshiEx, LLC and arguing that the Court should take the case to preserve sports integrity and protect market participants. For high-risk operators, this is the part where prediction markets stop looking like a niche legal dispute and start looking like a jurisdiction and controls problem.

1. The NFL’s brief, co-authored by former US Attorney General William Barr, asks the Court to grant review of Flaherty v. KalshiEx, LLC. The league says clearer rules are needed to preserve the integrity of professional sports events and to protect market participants.
2. The filing lands while the US Commodity Futures Trading Commission argues for exclusive jurisdiction over regulation of derivatives tied to sports events. The NFL says it has held discussions with prediction markets in recent months, but that the commission and various operators have resisted its requests to “implement appropriate safeguards” for sports event contracts.
3. The league’s core objection is not abstract. It pointed to contracts on whether a kicker will miss a field goal, the next penalty in a game, and even non-game-related items such as a phrase mentioned during a broadcast. In the NFL’s view, it is “at best unclear” whether the CFTC has the regulatory framework, oversight capacity and enforcement resources to keep prediction markets from jeopardizing game integrity.
4. Two major operators, Kalshi and Polymarket, both said integrity is central to their operations. Polymarket said it shares the NFL’s commitment to preserving the integrity of the game and is “constantly enhancing” its market surveillance tools. Kalshi said it tried to work constructively with the NFL to “collaborate on market integrity” and added that it is actively policing sports-related markets.
5. The stakes are not small: the dispute has been described as an existential struggle for the sports wagering and derivatives industries, with as much as $1 trillion in notional value up for grabs. That makes the Supreme Court’s response relevant far beyond one case name and one pair of operators.

NBA Commissioner Adam Silver also told CNBC in Macau, during an exhibition game, that there are issues around integrity in prediction markets. For anyone in sports-linked wagering or derivatives, the direction of travel is clear enough: the legal fight is now tightly tied to who gets to define and police market integrity.