The Penal Code Spine: How Section 337a Quietly Defines Everything Else

Here is a small thing I keep noticing when I read California regulatory filings: the deputy attorneys general almost never invent new vocabulary. They reach for Penal Code Section 337a — a statute older than every modern sportsbook in North America — and use it like a Swiss Army knife. That habit tells you something important. The state doesn’t actually need a new sports betting law to regulate sports betting. The old one does the work.

Section 337a is the wagering statute. In plain language, it makes it a misdemeanour to engage in the business of pool-selling, bookmaking, or recording wagers on contests of skill, speed, or power of endurance. Each clause has its own slot — pool-selling for parimutuel, bookmaking for fixed-odds, “recording bets” for the back-office side, “occupying any place” for the venue. A UFC fight, which is unmistakably a contest of skill and endurance, drops into that statute without needing any extension.

The crucial detail is who the statute targets. It is written around operators — the people who book the bets, accept the money, and keep the ledger. It is not primarily aimed at the individual punter putting £50 on a Bay Area lightweight. Prosecutions of individual bettors under Section 337a are vanishingly rare in modern California, and the AG’s office has never made personal bettor enforcement a priority. The shoe almost always drops on the book, the payment processor, or the venue.

That distinction does not make personal betting “legal”. It makes it under-enforced. The difference matters when you read commentary that says offshore betting is “tolerated” — what is actually tolerated is the bettor side. The book side is fully exposed, which is why no major US-licensed operator will accept California traffic.

Section 337a also gave the Department of Justice the analytical scaffolding for the DFS opinion published in July 2025. The Office concluded that participants in both pick’em and draft-style daily fantasy sports contests “place ‘bets’ on sporting events in violation of section 337a.” Those words — “bets”, “in violation of section 337a” — sit inside a 1909 statute that was written about horse racing parlour rooms. The AG didn’t need a 2025 law to reach DFS. He needed a careful reading of a 116-year-old one. That tells you almost everything about how California prefers to expand jurisdiction: by interpretation, not by legislation.

What Proposition 26 and Proposition 27 Taught the Industry

Two ballot measures in November 2022 were supposed to settle the California question for a decade. Both lost. Both lost badly. And the way they lost shaped every move that has happened since — including the one happening on your phone screen when you try to load FanDuel from Los Angeles.

Proposition 26 was the tribal-friendly version: in-person sports betting at tribal casinos, plus roulette and dice. Proposition 27 was the operator-friendly version: mobile sports betting via licensed online books, primarily DraftKings and FanDuel, with tribal coalitions getting a tax cut they considered humiliating. The two campaigns spent a combined sum north of $400 million attacking each other. Voters watched ads for months and concluded, reasonably, that they did not trust any of the players involved.

Prop 26 lost. Prop 27 collapsed: less than one in five California voters supported it, settling around 17% in favour. That figure became a kind of dark statistic among industry strategists — the proof point that throwing nine-figure ad budgets at a tribal-opposed ballot is a way to convert undecided voters into hard no’s. The 17% number is now quoted in nearly every commercial-side memo I read about the 2026/2028 windows, and it does more analytical work than any single tracking poll.

The aftermath has three lessons that the regulated industry has actually internalised. First, you cannot win California against the tribes; you can only win it with them. The tribal coalition is not a stakeholder, it is a veto-holder, and any operator-driven measure that does not have the Indian Gaming Association on side is dead on arrival. Second, the more money you spend on advertising, the more the voter dislikes the proposition — Prop 27’s ad density actively eroded support. Third, the public mood is not necessarily against sports betting; an August 2025 statewide poll showed about 60% of California voters open to legalisation in principle. The 2022 result was a referendum on the operators, not on the activity.

That gap — 60% conceptual support against 17% Prop 27 support — explains why a 2026 ballot question seems unlikely and a 2028 one is plausible. The tribes know they have the leverage. They are not going to spend it without getting the structural exclusivity they consider non-negotiable. The Prop 26 campaign and the Prop 27 campaign both insisted they had figured out the math; both were wrong. The industry’s homework now is to figure out a vehicle that does not require either side to lose face. That work is happening, but it is happening slowly, and behind closed doors. Nothing about the public conversation in California in 2026 suggests it is ready to be solved on a ballot in November.

AB 831 in the Law Stack

Assembly Bill 831 is the first piece of new California gambling law to actually bite since the Prop 27 disaster. Governor Newsom signed it on 11 October 2025 and it took effect on 1 January 2026. Its target is sweepstakes casinos — the workaround model that used “virtual coins” and “promotional sweepstakes entries” to sell what looked, walked, and quacked like online casino play.

The text of AB 831 makes operating an unlicensed sweepstakes a misdemeanour with fines from $1,000 to $25,000 per violation and up to one year of jail time. Crucially, the law’s definitions reach not only the operator but also software providers, marketing affiliates, and payment processors — the surrounding ecosystem that allowed the sweepstakes model to function. That breadth is the point. The legislature did not want to play whack-a-mole with shell entities; it wanted to dry up the supply chain.

AB 831 does not, on its face, target UFC betting. There is no “UFC clause.” But the bill matters to fight bettors because the sweepstakes model had quietly become one of the routes Californians used to wager on combat sports outcomes through pseudo-casino mechanics. With that route closed, the migration pressure pushes back toward offshore books and prediction markets — the routes I cover later in this guide and in the dedicated AB 831 article.

The Bonta DFS Opinion and What It Actually Said

On 3 July 2025, the California Department of Justice released Legal Opinion No. 23-1001, signed by Attorney General Rob Bonta and authored by Deputy AG Karim J. Kentfield. It is the most consequential single document in California sports betting law since Prop 27 failed. It runs to thirty-odd pages and it does one thing very firmly: it categorises daily fantasy sports — both the pick’em format and the draft-style format — as unlawful sports betting under Section 337a.

The operative passage is short and unambiguous. The Office concluded that “participants in both types of daily fantasy sports games — pick’em and draft-style — place ‘bets’ on sporting events in violation of section 337a.” Bonta added publicly that providing a DFS platform “to California consumers” is “in violation of the law as outlined in our formal opinion.” Then he said the part that mattered most: “The opinion is the first thing we were asked for, and we provided it. The next step is for us to enforce it.”

That second sentence is the one DFS operators studied for weeks. An AG opinion is not, by itself, a statute. It is the official legal interpretation of an existing statute and it carries enormous weight inside the executive branch. It tells district attorneys what view to take, tells local enforcement what posture to adopt, and — crucially — tells the operator’s general counsel what the most likely future looks like. Within months of the opinion, several large DFS pick’em products had begun adjusting their California offerings; some pulled out entirely, some restructured into season-long formats that lean further from event-by-event picks.

For the UFC bettor, the practical effects are concrete. DFS pick’em contests involving UFC fighters — pick three to land more than X significant strikes, for example — sit inside the same legal box as a moneyline placed on a regulated offshore book. From California’s perspective, both are Section 337a wagers. That equivalence is new. Before July 2025, the casual assumption inside the DFS industry was that pick’em was a skill-game cousin of fantasy football, sufficiently distant from a sportsbook to enjoy a different legal posture. The Opinion erased that distinction.

One nuance worth flagging: the Opinion’s reach is interpretive, not preventive. It does not give the AG a button to push that turns off DFS apps. Enforcement still has to go through normal channels — cease-and-desist letters, civil action, coordination with payment processors, in some cases criminal referral. That is slow work, and DFS operators with deep pockets can litigate the question for years. But the legal ground under their California product is materially less stable than it was two summers ago.

How Enforcement Actually Reaches the Bettor

This is the question I get asked more than any other. A reader from San Diego sends a polite email: “If I bet on UFC 320 from my couch, am I committing a crime?” The honest, lawyer-approved answer is “consult a lawyer.” The pragmatic answer is closer to: “In theory, yes. In practice, no California prosecutor has any appetite to find out who you are.”

The enforcement architecture in California, like in most US states, is pointed at operators, payment rails, and venues. Section 337a’s bookmaking subsections describe activity that is, by design, commercial — keeping a book, recording bets, occupying a place where wagers are received. The casual user who places one wager from a couch is technically violating Section 337a’s gaming clause but is functionally invisible to enforcement priorities. There is no California sting operation set up to catch individual offshore punters. There has been no public criminal case against a California resident for a personal sports wager in a generation.

What enforcement does target, with increasing aggression, is the supply chain. Payment processors moving money to offshore books, software vendors enabling sweepstakes mechanics, marketing affiliates selling California traffic to grey-market operators — those are the targets. The FBI’s January 2026 cyber alert on illegal sportsbooks reframed offshore operators as adjacent to organised crime, drug trafficking, and human exploitation. That language was not chosen to scare punters. It was chosen to justify federal coordination on the operator side.

The practical takeaway for an individual California UFC bettor is that the legal risk to you personally is overwhelmingly financial and structural, not criminal. Your money is at risk because the book has no US-enforceable consumer protection. Your account is at risk because a payment processor can be shut down. Your bet itself is at risk because the operator can void it. What is essentially not at risk, based on the last twenty years of California practice, is your personal liberty.

I want to be careful here. “Almost never enforced” is not “legal.” A statute that is not enforced today can be enforced tomorrow if the politics shift. And if California ever does pass a regulated framework, the transitional period will likely involve a hardening of enforcement on every channel that was not part of the new system. Bettors who treat under-enforcement as permanent status often discover the difference at the worst time.

The Tribal Wall

You cannot understand California gambling law without understanding the tribal compacts. Sixty-three of the state’s 109 federally recognised tribes own 66 casinos. Their exclusive right to operate Class III gaming — slot machines and house-banked card games — is locked in by compacts negotiated under the federal Indian Gaming Regulatory Act. Those compacts are the political bedrock of the entire state’s gambling economy, and they are why every attempt to launch non-tribal sports betting in California has hit the same wall.

The tribal coalition is not a single voice; it is several. The California Nations Indian Gaming Association — CNIGA — is the most visible, and its statement after the Bonta DFS opinion is worth quoting in full. CNIGA welcomed the opinion and added that “although CNIGA commends AG Bonta’s action to uphold the rule of law in California, it is absolutely clear that California has long turned a blind eye to the illegal gambling market — at the direct expense of tribal governments. Countless millions, if not billions, have been illegally wagered over the past decade.” That sentence does two pieces of work. It frames DFS, sweepstakes, and offshore as a loss line on tribal revenue, and it positions the tribes as the moral plaintiffs in any future legalisation conversation.

The economic stakes back the rhetoric. Tribal casinos in the Sacramento region — California plus northern Nevada — generated $12.1 billion in gross gaming revenue in fiscal 2024, more than a quarter of all tribal gaming revenue in the US. Nationally, tribal casinos collected $43.9 billion in FY2024, the fourth straight record year. Any law that lets a non-tribal operator into the California market without compensation is, from the tribes’ perspective, a direct extraction from that base.

For UFC bettors, the immediate practical consequence is that California tribal casinos do not currently offer sports betting on premises. The compacts that authorise their existing gaming do not extend to sportsbook operation. To change that, the tribes would need a new constitutional amendment — and they will not allow one to move without exclusivity, which is exactly the structure operator-driven measures like Prop 27 refused to accept.

The Realistic Path to a Regulated California Market

I want to close on a forecast, because every reader who wades through 3,000 words on California gambling law wants the same thing at the end: tell me when this changes. The honest answer is not as comforting as either side wants.

A 2026 ballot question is unlikely. The tribal coalition has not signalled willingness to anchor a measure, the operator side has not produced a structure the tribes will accept, and the legislative deadline for qualifying a constitutional amendment for the November 2026 ballot has narrowed every month. The window is still mathematically open but practically very small. If a measure does qualify, it will look much more like Prop 26 — tribal-anchored, in-person first — than Prop 27, and it will probably restrict mobile to a tightly limited tribal partnership model.

A 2028 outcome is plausible. By then, several things that are currently missing will have time to develop. The tribes’ negotiating leverage will be tested against the visible loss line that prediction markets, DFS, and offshore have been carving into their revenue. The AG’s enforcement of the DFS opinion will have shown the limits and the bite of unilateral executive action. And the political class will have had two more election cycles to absorb the 17% Prop 27 number and learn that the public’s 60% open-to-legalisation conceptual support does not translate into ballot approval for any specific text.

What needs to align for a 2028 win is roughly this. The tribes need a model they trust — likely exclusivity over mobile, or a tribally-owned operator structure, or a hybrid with limited commercial partners working under tribal licence. The commercial operators need a path that gets them enough volume to matter. The state’s general fund needs a number that makes the deal politically attractive at the legislative committee level. And the campaign needs to learn from Prop 27 that ad volume past a certain threshold actively erodes voter support.

None of that is impossible. None of it is close to done. For a California UFC bettor reading in 2026, the practical inference is straightforward: the legal landscape on your phone today is the legal landscape you will have through the next two PPV cycles, probably through the next three. Offshore books, prediction markets in some form, and a shrinking DFS option are the channels. Tribal in-person sports betting is not coming online before late 2028 at the earliest. Any timeline shorter than that is selling something.

The good news is that the legal materials are now public, dense, and stable enough to study. The Penal Code Section 337a baseline, the Bonta Opinion, the AB 831 text — these are documents that are not going anywhere. Read them once, and you will understand most regulatory news that breaks in California for the next three years better than the headline writer does.