Our own National Post recently scandalized its famously conservative readers with a headline claiming that “about half of Canadians who drive while high insist pot doesn’t impair them.” The article — When is stoned too stoned? — further sensationalized the “crisis” by noting that “nothing would make [20 per cent of those surveyed] stop driving while stoned.” With the Trudeau government poised to legalize marijuana, it was enough to send neocons into paroxysms of paranoia, our roads sure to be turned into killing fields by the demon killer weed.

It certainly didn’t help matters that CNN Money also ramped up the hype by noting that the number of fatalities involving drivers who had consumed marijuana had doubled since the state of Washington had legalized pot for recreational consumption. About time, then, that many jurisdictions are quickly instituting alcohol-like limits to the THC content one can have in their bloodstream and still be allowed to drive.

The only problem is that the stoners might have it right. Marijuana, by most measures, is not in any way the scourge that alcohol is. We may in fact be perfectly competent to drive while “baked.” At the very least, the methodology currently being employed to prevent those impaired by excessive THC consumption may be grossly ineffective and, at worst, prejudicial.

The problem with trying to weed out those too toasted to drive is two-fold, namely that the testing is faulty and, perhaps more surprising, that the evidence that getting high results in more automobile accidents — as it does so conclusively for alcohol — is very thin indeed.

For one thing, the current testing regime is flawed. Essentially following the protocol employed to measure alcohol impairment, current restrictions are based on limiting the amount of Tetrahydrocannabinol (THC) in your bloodstream while driving. Besides the compete lack of consensus on how much THC is too much — current limits under discussion vary from as little as one nanogram per millilitre of blood to five ng — there doesn’t seem to be any direct correlation between increased levels of THC in the blood and traffic fatalities. Even Peter Kissinger, CEO of the American Motorists Association, one of the organizations for marijuana proscription, says “It’s simply not possible today to determine whether a driver is impaired based solely on the amount of the drug in their body.”

The problem, say medical experts, is that THC, unlike alcohol, can stay in your bloodstream for weeks, long after any desultory effects have worn off. Jolene Forman, a staff lawyer for the Drug Policy Alliance, a drug-reform advocacy group, told the New York Times that using roadside THC blood tests to prove impairment is “equivalent to a test that shows that you had a glass of wine three nights prior.” Indeed, the main reason to implement a blood test for THC content would seem to be that constabularies find an easily quantified objective restriction more convenient than a subjective test for impairment.

And, it is in the area of just how “impaired” one is after firing up a blunt where the reasoning behind marijuana restrictions gets even murkier. While there is little doubt that THC somewhat impairs certain motor skills — for instance, compromising the ability to steadily walk heel-to-toe — numerous driver simulation studies have shown that those driving under the influence of marijuana, in complete contradistinction to the aggressive driving habits of those under the influence of alcohol, compensate by driving more cautiously. The University of Iowa Carver College of Medicine, for instance, found that, after smoking a “marijuana cigarette,” 85 subjects in a double-blind study performed virtually the same after smoking cannabis as they did sober, with “no differences found during the baseline driving segment [and the] collision avoidance scenarios.”

Indeed, a Canadian senate study showed that while “evidence of impairment from the consumption of cannabis has been reported by studies using laboratory tests, driving simulators and on-road observation,” these results “do not necessarily reflect ‘impairment’ in terms of performance effectiveness, since few studies report increased accident risk.” And no less than the U.S. National Highway Traffic Safety Administration concluded that once you factor out age, gender, race and alcohol use, “drivers who tested positive for marijuana were no more likely to crash” than those who were stone cold sober. The one notable exception is the combination of alcohol and cannabis, which seems to exacerbate the effect of both. That senate study suggested lowering the alcohol limit to 40 milligrams of alcohol — as opposed to the current limit of 80 mg — per 100 millilitres of blood, in the “presence of other drugs, especially … cannabis.”

Read more: Top reasons you’ll be pulled over by police this summer

Even more telling is that, according to a University of Chicago study, marijuana use may reduce accidents. According to Medical Marijuana Laws, Traffic Fatalities, and Alcohol Consumption, the 19 states that have legalized marijuana saw “an 8 to 11 per cent decrease in traffic fatalities” in the first full year after the medical marijuana laws were passed. The hypothesis is that drivers are substituting marijuana for alcohol, Ottawa’s Traffic Injury Research Foundation theorizing that “these sharp declines may be due to the decreased number of alcohol-impaired drivers on the road as a result of the legalization of medical marijuana.” Whatever the case, it turns out the reason that more Washingtonians are dying in car accidents with THC in their bloodstream isn’t so much that pot consumption is causing more accidents, but simply that more people are smoking pot.

Nonetheless, it’s not difficult to see there’s still a cautionary note of ambivalence in the medical/safety community about disregarding the potential dangers of marijuana consumption on driving safety. Despite (at least) some evidence that lighting up a fat one presents little additional risk of being in an accident, no one wants to sound pro-ganja. Indeed, reading between the lines in these numerous studies, one gets the impression that most of the authors don’t seem so much worried about the effects of marijuana while driving, as the blowback from not being worried about the effects of marijuana while driving.

Note: This article in no way promotes the consumption of marijuana before, during or, for that matter, after the driving of an automobile. It does not, in fact, promote the use of cannabis at any time. Indeed, although the author readily admits to misspending his youth (back in the days when Thai Stick ruled the THC world), except for a weekend of reminiscence in Amsterdam some 20 years ago, absolutely no illicit substances have found their way into his bloodstream since graduating from university in 1983.