Indian Gaming and Prediction Markets: Tribal Amici Ask SCOTUS to Step In

Two amicus briefs—one filed October 6 by the Cabazon Band of Cahuilla Indians (“Cabazon Brief”), and one filed October 8 by 130 federally recognized Tribes and 15 tribal organizations (“Multi-Tribe Brief”)—now offer additional insight about what the Third Circuit’s ruling, if left undisturbed, would mean for Indian country. The amici compare Kalshi and other prediction markets to historic prospectors who took gold, minerals and other precious resources from Indian lands. “[I]t seems old habits die slowly,” they observe, quoting Justice Gorsuch’s dissent in Oklahoma v. Castro-Huerta. “[L]ike the prospectors of old,” the amici argue in the Multi Tribe Brief, “Kalshi and its ilk are infringing tribal sovereignty and threatening a vital tribal resource.”

A Question of Tribal Sovereignty
The briefs, taken together, trace tribal authority over gaming on Indian lands from the Supreme Court’s seminal decision in California v. Cabazon Band of Mission Indians, through Congress’s 1988 enactment of the Indian Gaming Regulatory Act (IGRA), and provide a clear explanation of the importance of gaming to tribal sovereignty today. (We have previously summarized some of this history, and how it has set the table for today’s disputes around prediction markets and internet gaming.) While certain Tribes prohibit gaming, sometimes on ethical, spiritual or cultural grounds, those who permit gaming do so through complex Tribal gaming ordinances and tribal-state compacts. As the amici explain, those compacts rest on IGRA’s “fundamental premise” that only Tribes may allow gaming on Indian lands.

The tribal amici argue that Kalshi’s offering of sports-event contracts on Indian lands disregards Tribes’ sovereign power to prohibit or permit on-reservation gaming, and diverts significant revenues away from Tribes who, “under IGRA, are intended to be the primary beneficiaries of on-reservation gaming,” according to the Cabazon Brief.

The Cabazon Band submitted sworn declarations from two tribal officials to illustrate the potential impact to Tribes. As noted in the declarations, the Cabazon Band—through its federally approved gaming ordinance and state gaming compact—prohibits on-reservation sports betting, yet the tribal officials were able to download the Kalshi mobile application and place bets on certain sporting events while on the Cabazon Reservation. The tribal amici explain in the Multi Tribe Brief that Kalshi is proceeding down this path “without tribal authorization, without state cooperation, and with almost no regulatory safeguards.”

Economic Impacts
The amici describe gaming as a vital source of tribal economic development, particularly given what Justice Sotomayor called “the insuperable (and often state-imposed) barriers Tribes face in raising revenue through more traditional means,” in Michigan v. Bay Mills Indian Community. Gaming revenue funds healthcare, housing, education and public safety. Overall, nearly 250 tribal governments operate gaming facilities on Indian lands across 29 states. In fiscal year 2025, those facilities generated more than $46 billion in total gross gaming revenue.

Through inter-tribal revenue sharing and charitable contributions, gaming revenues even support Tribes that conduct little or no gaming at all. In California, where inter-tribal revenue sharing is codified in state law, gaming Tribes shared, in a single year, more than $80 million with economically disadvantaged Tribes and contributed another $77 million to other Tribes and local communities.

The Multi-Tribe Brief also describes how tribal gaming supports thousands of jobs in Indian country and surrounding communities, many of which are in rural areas with otherwise smaller economic bases. The Cabazon Band, quoting the D.C. Circuit in San Manuel Indian Bingo & Casino v. NLRB, reminds the Supreme Court that, thanks to gaming revenues, the San Manuel Band of Serrano Mission Indians in California “can now boast full employment, complete medical coverage for all members, government funding for scholarships, improved housing and significant infrastructure improvements to the reservation.”

An Uneven Playing Field
The tribal amici argue that Kalshi competes for gaming customers while “skirting” the regulatory costs, revenue sharing and gaming rules that apply to tribal gaming operators under IGRA and applicable state gaming laws. Tribes conducting gaming on Indian lands must comply with tribal, state and federal requirements under IGRA; Tribes licensed to offer gaming off-reservation (such as the Seminole Tribe of Florida, which operates off-reservation casinos and internet gaming through the Hard Rock brand) must follow state gaming rules. Those requirements protect the integrity of gaming and include safety measures such as age limits, restrictions on advertising and prohibitions on gambling by those who are visibly intoxicated.

Tribal governments collectively spend more than $450 million annually on gaming regulation and employ more than 6,000 gaming regulators, according to figures cited in the Multi-Tribe Brief. In contrast, Kalshi contends it may be regulated only by the Commodity Futures Trading Commission (CFTC). In the Multi Tribe Brief, the amici call the resulting disparity “an affront to tribal sovereignty, an end-run around Congress and the States, and a violation of basic notions of fair play and sound regulation.”

Why Review Now?
Both tribal amicus briefs urge the Court to decide the issue now. Ordinarily, the amici acknowledge, “issues with this great an impact on Indian country ought to be decided in cases where Tribes themselves are parties.” But here, as the amici explain in their Multi Tribe Brief, “the outpouring of tribal support for this petition is proof of the urgency of this Court’s review.”

“The uncertainty itself works an injury,” the amici write. While the question remains open, Tribes “must make difficult decisions about their future, including how much they should invest in and rely on the gaming industry.” This difficulty is heightened by the existence of a circuit split between the Third Circuit, on the one hand, and the Ninth and Sixth Circuits, on the other hand, which could mean that the rules governing prediction markets—and the resulting impacts on Tribes and tribal gaming—vary from region to region. Each day that prediction-market platforms direct gaming apps into Indian lands, the amici argue, Tribes suffer further infringement of their sovereignty.

 “This Court,” the amici urge in their Multi Tribe Brief, “can and should intervene to restore order.”