Twenty-seven US states have backed tribal appellants in a federal gambling law case against Kalshi that could help define the future trajectory of gambling regulation across the United States. As market analysts and investors continue to pour capital into the fast-growing prediction markets sector, a fundamental legal dispute is unfolding over who has the authority to regulate wagers tied to real-world events. State governments and tribal regulators, or federal agencies overseeing financial markets? Few have more at stake than Indigenous American tribes, who have for decades exercised sovereignty over gaming on their lands under the Indian Gaming Regulatory Act of 1988 (IGRA). That framework governs how tribes may offer gambling, including sports wagering, through negotiated deals with states. This system, tribes argue, is now being threatened by prediction markets operating under federal commodities regulation. In Blue Lake Rancheria et al. v. Kalshi Inc., that long-running tension has reached a potential boiling point. Tribal governments argue that allowing nationwide sports-linked event contracts through federal regulation would not only bypass state gambling law but also undermine decades …