If you’re a gambling man or woman (and two of this fall’s seven California ballot propositions are about gaming), don’t bet the house against either November’s Prop. 26 or Prop. 27.

Both these competing initiatives aim to legalize what once was criminal in this state. Legalizing onetime vices seems to have become a ballot-box favorite.

The recent history of marijuana laws makes this clear, as voters first approved medical marijuana and later okayed full recreational use of the weed, to the point where it’s now hard to find a city or town without at least one cannabis dispensary.

The history of legal gambling in California is only slightly less telling, voters in 2000 approving Indian gambling on once poor and desolate Native American reservations by an overwhelming 65-35 percent margin. They later drew a line and in 2004 refused to allow slot machines in urban card rooms and horse race tracks.

But in 2008 tribal compacts vastly expanding the number of slot machines on some reservations were approved easily.

Now come Props. 26 and 27, both aiming to legalize sports betting, a huge pastime from which Californians have been formally excluded. This still sends many thousands to Nevada for live betting and onto illicit offshore websites for online wagers.

It’s still unclear what would happen if both initiatives pass. If there’s a precedent here, it might be the 1978 battle between the Proposition 13 property tax limits and milder limits in the rival Proposition 10. In that case, both passed, with 13 getting more votes and standing as untouchable law ever since.

The betting initiatives differ widely: Prop. 26 allows sports betting, but in person only at casinos on semi-sovereign reservations and at four horse race tracks – but not online. It would also allow casino tribes to sue cardrooms over some games they offer, while okaying dice games and roulette at Native American casinos.

Meanwhile, Prop. 27, backed by online giants like FanDuel, DraftKings and BetMGM, legalizes online and other mobile sports betting, but would see the big operators each partner with Indian tribes. Fully 85 percent of tax revenue produced from this would be earmarked for housing and to help solve homelessness.

Both measures provide avenues for almost unlimited growth of the interest groups behind them. It’s hard to see how they could co-exist, so the strong likelihood is for drawn-out legal battles over which one will govern, if both pass.

So far, more than five dozen casino tribes are backing Prop. 26, which they see as their ticket to even more prosperity than they now enjoy. Most likely, more Native Americans would gain wealth under 26 than with 27, where the bulk of the money would go to the big gaming companies and a relative pittance to aid the unhoused.

The measures promise to make new money for many tribes that already rake in plenty; there’s precious little to protect gambling addicts from losing whatever savings they may have.

Today’s Indian gambling, confined for the most part to reservations, also does little to protect gamblers from addiction. But at least now they usually must go to tribal lands to activate their habit.

Cardroom operators, longtime exploiters of loopholes in restrictive state laws, whine that if 26 passes, it will prevent them from ever getting into games they now cannot run, but which remain potential sources of riches.

Their committee, with the pious-sounding name “Taxpayers against Special Interest Monopolies,” says 26 would “guarantee tribal casinos a near monopoly on all gaming in California, adding roulette, craps and sports wagering to their current monopoly on slot machines.”

All this leaves little doubt we are seeing a contest between heavily monied interests over who will become the most wealthy. That’s why, having raised more than $300 million before the Fourth of July, this campaign figures to become the most expensive state electoral contest ever, of any type.

The healthiest response from voters would be to reject both measures, but given the pent-up demand for sports betting in California and voters’ prior approval of things long considered vices, that’s not likely to happen. Which means big-time sports betting will soon arrive here, with a corps of lawyers likely to decide its eventual shape and scope.

Email Thomas Elias at [email protected]. His book, “The Burzynski Breakthrough, The Most Promising Cancer Treatment and the Government’s Campaign to Squelch It” is now available in a soft cover fourth edition. For more Elias columns, visit www.californiafocus.net