Legalization of marijuana for recreational use will, by all indications, be a question taken up by the Minnesota Legislature in 2023. (Mel Melcon, TNS - TNS/The Minnesota Star Tribune)

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If you have a "SCIENCE IS REAL" sign in your yard and you're in favor of legalizing recreational marijuana, you should do some reading. The evidence emphatically disfavors legalization.

A good place to start is "Smokescreen: What the Marijuana Industry Doesn't Want You to Know" (2021) by Kevin Sabet of the Yale Medical School, a drug policy adviser to Presidents Bill Clinton, George W. Bush and Barack Obama. It includes 355 footnotes to medical and social scientific research. Here are a few vital points:

• Frequent use of high-potency marijuana disrupts brain development in teenagers and young adults (brains develop to at least age 25). Pot impairs academic performance, and it can decrease intelligence.

• Marijuana is associated with psychosis — paranoia, schizophrenia, bipolar disorder. Psychiatric hospital admissions increase sharply after legalization.

• Contrary to what we've been told, marijuana is addictive. Compulsive use can cause all sorts of pathologies, including hyperemesis (chronic vomiting), depression and suicidality.

• Fatal car crashes in which a driver tests positive for THC (the psychoactive component in pot) increase sharply after legalization.

The underlying menace is potency. Today's marijuana is not the Woodstock weed of bygone years (1% to 3% THC). Genetic engineering has brought plant potency above 17%, and concentrates (in edibles, vapes and other products) can approach 99%.

The notion that bureaucratic regulation will limit potency is laughable. Illegal dealers flourish in states that have legalized recreational pot. They undersell dispensaries because they don't pay taxes, and they attract buyers precisely because their pot is more potent than the regulated pot.

The arc of the science is clear. Sabet says that 20,000 peer-reviewed studies show physical, mental or developmental impairments related to pot. Why, then, has legalization enjoyed such success since the first states legalized recreational pot in 2012?

The answer is massive promotional efforts bankrolled by billionaires and big business. In 2020, when five states legalized, pot proponents outspent opponents by $19.8 million to $1.3 million. These vast cash disparities drown out the science.

The billionaire promoters come from all political backgrounds. They include the anarchical George Soros, the Trumpian Peter Thiel, and the late insurance tycoon Peter Lewis. Soros alone apparently has shoveled $200 million into legalization.

Meanwhile, Big Tobacco has repositioned itself to sell marijuana. The makers of Marlboro and Winston cigarettes are key promoters of pot. Sabet names many other corporate behemoths who've poured in waterfalls of cash.

We all know how these forces have messaged and marketed legalizing pot. They've rebranded the skunky weed as "cannabis," to make it sound refined. They proclaim that Everybody's Doing It — that legalization is inevitable and resistance is futile. They broadcast images of beaming young people buying and selling edibles in dispensaries and bars.

This consumer protection fiasco is strikingly similar to the cigarette fiasco of the 1950s. At that time, too, the science was clear: Lung cancer was killing thousands of people, and cigarette smoke was the cause. But Big Tobacco disputed the evidence, and massive advertising drowned out the science and normalized cigarettes.

Sabet argues that normalization is pivotal. Putting pot into bars and storefronts, promoted by high-tech advertising, sends a message that it is safe. Young people's perception of risk drops drastically in states that have legalized pot. The law should give warning that pot is a menace to health and not a fit form of recreation.

Sabet argues that we should decriminalize and expunge past convictions for personal use, but ban cultivation and sale of marijuana. That gives us a fighting chance to keep the malignant genie in the bottle while scientific studies advance and educational efforts proceed.

Sabet, incidentally, defies stereotypes. He's an ethnic and religious minority (Iranian-Yemeni; Baha'i). He strongly admires Barack Obama. His instincts clearly are those of a Democrat, and he's confounded when Democrats march in lockstep toward legalization.

Democrats pride themselves on being the party of science and consumer protection and the scourge of tobacco companies. Commercializing marijuana utterly compromises those values.

We need some brave Democrats in the Minnesota Legislature to break with Soros and Thiel and Big Tobacco and Jesse Ventura and the rest of the Brobdingnagian parade that's leading us toward legalization. Decriminalize. Expunge. But don't commercialize and normalize marijuana. Science militates for this approach.

John Hagen, of Minneapolis, is an attorney and writer.