California 2028 Sports Betting Initiative: The Partner-Exclusion Question

California's tribes are preparing a 2028 ballot initiative on sports betting, and one design question is already shaping the debate: whether a sportsbook that also works with a prediction market should be allowed to operate in the state. The question surfaced in an October 2026 Capitol Weekly report republished by Times of San Diego, which quoted tribal leaders describing a measure that would bar any sportsbook working with a prediction market from entering California. This analysis examines what such a provision would mean, how it fits the tribes' broader strategy, and what legal and political questions it raises.

Where the tribal position stands

California voters rejected two sports betting measures in 2022. Proposition 26, backed by tribes, would have allowed in-person sports betting at tribal casinos and horse racing tracks. Proposition 27, backed by DraftKings and FanDuel, would have legalized online sports betting. Both failed in what was described as the most expensive ballot campaign in U.S. history. Our report on why California tribes are deferring sports betting until 2028 covers that history and the tribes' decision to wait.

Since then, prediction markets have changed the landscape. Platforms such as Kalshi and Polymarket offer event contracts, including on sports, under federal commodities oversight, and commercial sportsbooks including DraftKings and FanDuel launched prediction market products in late 2025. California tribal leaders have called these products a threat. James Siva, chairman of the California Nations Indian Gaming Association, was quoted as saying prediction markets are the largest threat tribes currently face, and as specifying that the tribes' objection concerns sports-event contracts. Victor Rocha, a Pechanga Band member and Indian Gaming Association conference chairman, was quoted as saying DraftKings would have to be held accountable once prediction markets lose sports betting.

The partner-exclusion concept

According to the report, Rocha said the 2028 initiative would bar any sportsbook that works with a prediction market from entering California. The detailed language has not been published in the sources reviewed here, so what follows is analysis of the concept rather than of final text.

A partner-exclusion clause would reverse the usual bargaining dynamic. In most states, commercial operators seek market access and tribes or legislatures set the terms. Here, tribes would write conditions into the ballot measure itself, making exclusivity from prediction markets a precondition for any commercial partner. The report notes that DraftKings and other sportsbooks sent CNIGA a letter promising to work exclusively with tribes and to close prediction markets when legal sports betting arrives in California. A ballot provision would convert that promise into an enforceable legal condition.

The report also describes a June 2026 Request for Information from CNIGA to commercial operators outlining three possible models, including a single tribe-run platform. Operators with existing California tribal partnerships, including Caesars, Boyd and Hard Rock, were described as likely beneficiaries. For how a single platform might work, see our analysis of the California sports betting alliance and single-body framework.

Legal and political questions

Several questions follow. First, how would the measure define "working with" a prediction market? Corporate affiliations, licensing agreements, data sharing and marketing relationships could all be argued to fall within or outside the term. Precise drafting would matter, because broad language could exclude desirable operators and narrow language could be sidestepped through separate corporate entities.

Second, the federal-state boundary remains unsettled. The report says a Ninth Circuit ruling in a case with two California tribes as plaintiffs found prediction markets likely violate state law on tribal land, while California tribes and Attorney General Rob Bonta filed amicus briefs urging the U.S. Supreme Court to hear a Third Circuit case that found federal law preempts state regulation of sports event contracts. The NFL also backed review. A Supreme Court decision could reshape the premises of any 2028 measure. Our coverage of the Ninth Circuit Blue Lake Rancheria ruling and the broader debate over prediction markets and IGRA exclusivity provides legal background.

Third, tribal unity is not complete. The report notes that three California tribes, including the Alturas Indian Rancheria in Modoc County, have partnered with Kalshi, and Siva called that disappointing while saying he did not hold it against them. A statewide initiative requires broad tribal support, and divergent positions could complicate the coalition. See our analysis of how tribal consensus on prediction markets is fracturing.

What to watch

Observers should watch for published initiative language, the outcome of the Supreme Court petitions, and any further operator commitments. Under Proposition 1A of 2000, California tribes hold constitutional exclusivity over casino-style gaming, which gives them leverage in any negotiation over sports betting. For ongoing coverage, visit the California state hub, and consult the Legal Guide for background on Class III gaming and compacts.

The partner-exclusion idea is best understood as a negotiating and legal-protection tool: it aims to ensure that any commercial operator entering California does so on terms that protect the tribes' position against prediction market competition. Whether voters, courts and operators accept those terms will determine whether the 2028 effort succeeds where the 2022 campaigns did not.