Leagues split: NFL sues while MLB, MLS, NHL sign deals

The NFL’s opposition to prediction markets is increasingly at odds with the commercial approach of other major US sports leagues. In an October 8 Supreme Court brief against Kalshi, the league argued that sports event contracts constitute gambling rather than swaps, according to predictionmarketsworld.com.

Commercial deals meet legal resistance

MLB named Polymarket its exclusive prediction market partner in March, with the agreement reportedly valued at $150-300 million over three years, according to predictionmarketsworld.com. MLS signed an exclusive agreement with Polymarket in January, while the NHL licenses to both Kalshi and Polymarket. The NBA is reportedly nearing agreements.

Those arrangements show that leagues are pursuing different responses to the same products: some are establishing commercial relationships, while the NFL is challenging their legal treatment. The NFL’s filing is an amicus brief urging Supreme Court review, rather than a new lawsuit brought by the league.

Supreme Court timetable shifts

October 8 was the deadline for amicus briefs in New Jersey’s petition in Flaherty v. KalshiEX. According to predictionmarketsworld.com, Ohio led a filing involving 39 state attorneys general and DC. The Cabazon Band of Mission Indians, whose 1987 Supreme Court case established the modern tribal gaming framework, also urged the Court to hear the case.

The Court granted Kalshi a 30-day extension to respond, moving its deadline from October 8 to November 9. That change pushes a possible decision on whether to take the case toward December or early 2027, the outlet reported. The underlying dispute concerns whether the CFTC’s jurisdiction under the CEA displaces state gambling law.

What it means for prediction markets

• League partnerships and legal authority remain separate questions. MLB, MLS and NHL agreements demonstrate commercial interest, but do not resolve the dispute over how sports contracts should be regulated.
• The next procedural date is November 9. Kalshi’s response deadline is not a ruling date; a decision on Supreme Court review could follow in December or early 2027.
• The NFL’s position is not shared across the major leagues. Readers tracking adoption should distinguish the NFL’s legal opposition from existing partnerships elsewhere and the NBA’s reportedly pending agreements.