The NFL tells the Supreme Court that sports prediction markets are gambling, breaking with MLB and the NHL

The NFL has taken sides against the prediction markets. In a brief filed at the Supreme Court on Thursday, the NFL argued that contracts on the outcome of games are gambling, not the financial swaps their sellers say they are, and that states should be able to regulate them.

The brief backs New Jersey's gambling regulators, who have asked the court to take up their fight with Kalshi. The case, Flaherty v. KalshiEX, turns on whether sports contracts sit under the exclusive authority of the Commodity Futures Trading Commission or whether state gambling laws also apply. Lower courts have split on the question.

The league said some contracts "present significant and immediate threats to the integrity of sporting events and to market participants," Axios reported. It objects to markets on individual plays, player injuries and officiating calls, and says federal regulators turned down safeguards it asked for, including a minimum trading age of 21.

The stance sets the NFL apart. Major League Baseball and the National Hockey League have struck partnerships with prediction market companies, The Block reported. Kalshi rejected the league's argument, saying it is committed to protecting the integrity of games and citing those partnerships.

A CFTC spokesperson told Axios the agency had engaged with the league and that it was unfortunate the league declined an agreement on cooperation and information sharing.

The justices have not said whether they will hear the case. Kalshi has until November 9 to respond to New Jersey's petition, Axios reported.