As a libertarian of long standing, I’m on the record as being in favour of legalizing cannabis since long before it was cool (geeky and perpetually uncool libertarians probably helped keep it from being cool for at least a few years longer). I’m not enthused to hear that we may have been undersold on the risks of cannabis use … not that the government didn’t try telling is it was deadly, deadly poison (they did, repeatedly, and at great length), but they institutionalized the role of the boy who cried wolf, and every illegal narcotic got basically the same description. I’m actually not kidding here: the first health class I got in middle school included a lecture and a pamphlet on the dangers of pot; the second class covered the dangers of cocaine; the third warned against LSD; and so on … but they used a copy/paste to discuss the physical and mental risks of the different drugs, and they all read the same way. All those evil drugs are evil, bad, and rot your brain. Knowing that the pothead (“Hi, Gary!”) at the back of the class hadn’t suddenly had a psychotic break and tried to fly off the top of the school was the first hint that we were being oversold on the real world risks of (some) illegal drug use. The declared fact that some illegal narcotics actually are deadly, deadly poison ran up against the observed fact that a significant majority of people over the age of fifteen had tried cannabis and found it somewhat less scary than advertised.

Along with the beginnings of doubt that the government was being honest with us, and the clear understanding that even if using drugs wasn’t as dangerous as we were told, we shared a growing awareness that being caught with drugs by the police was significantly more dangerous and possibly deadly. Officer Friendly would shoot you down like a mad dog if he thought you were one’o’them drug-crazed hippies. It certainly changed the social dynamics of any interaction with Officer Friendly’s fellow heavily armed co-workers…

In the National Post, Barbara Kay suggests that not all the dangers of cannabis use were mere government propaganda:

Some years ago, in conversation with his wife, a forensic psychiatrist specializing in mentally ill criminals, former New York Times reporter Alex Berenson observed that the perpetrator of a recent violent crime had been high at the time, and had smoked pot regularly all his life. Her response — “Yeah, they all do” — jolted him. The result was his book, Tell Your Children: The Truth About Marijuana, Mental Illness and Violence.

Much of the referenced material in Berenson’s book had not yet been published a decade ago. But more recent studies only confirm what a few intrepid researchers were already warning about then.

Indeed, as I noted in a 2008 column, the head of the Medical research Council in the U.K., Professor Colin Blakemore, who in 1997 had been the moral authority behind a pot-legalization campaign, unequivocally reversed his pot-friendly stance in 2007, stating: “The link between cannabis and psychosis is quite clear now; it wasn’t 10 years ago.”

If you haven’t energy for a whole book, but would invest in 16 pages on the subject, you will be well rewarded by Steven Malanga’s in-depth article, “The Marijuana Delusion,” in City Journal‘s June issue. Here you will find debunked the blithe claim, still received as gospel by progressives and libertarians, that pot is virtually harmless and even therapeutic.

Unlike marijuana, real medications are deeply researched before coming on the market, and may attest to proven benefits, but are obligated to admit potential harms. Is pot a medicinal drug or a placebo? Nobody really knows. One may argue “who cares, as long as it works” (anecdotally I hear that pot works, and also that it doesn’t work), but that isn’t the point, since the legalization movement made medical claims for pot in order to bring the public onside politically. There was no will on the movement’s side to discover even radically fortified pot’s downsides.

The knowledge was out there for those interested. In 1987 a study of nearly 50,000 Swedish military conscripts followed for drug use over 15 years found that frequent pot use in teenhood was linked to a six-fold risk of schizophrenia as compared with non-usage. A 2004 meta-analysis of studies on pot use came to a similar conclusion. These studies, and others, are suggestive that heavy marijuana consumption, particularly in youth, may cause serious mental health problems. Yes, it is possible that the link isn’t entirely causal; people with mental health issues may be more likely to use marijuana heavily. But at the very least, this ought to be an issue of ongoing concern, particularly now that marijuana is legal in Canada and in an increasing number of U.S. states.