How bad is stoned driving, and what should we do about it?

“Stoned driving” isn’t nearly as bad as drunk driving. How about a zero BAC limit when THC is present?

Dishonest advocacy aside, what are the actual risks of stoned driving? The answer, from what seems to be a well-done case-control study, is that driving stoned is hazardous, but much less hazardous than driving drunk. (A relative risk of 1.83 – meaning that driving a mile stoned is about as risky as driving two miles sober – strongly suggests that cannabis-impaired driving is a problem, but also that it isn’t much of a problem; the relative-risk number for alcohol is over 13.) On the other hand, the same study shows that adding cannabis or other drugs to alcohol substantially worsens the odds: alcohol-and-something-else has a relative risk of 23.

Given those numbers, and the technical difficulty of identifying cannabis-impaired driving (because impairment doesn’t track cannabinoid levels in blood nearly as well as it tracks alcohol levels) I’d propose the following rule: anyone who tests positive for cannabis on a mouth swab (which detects use within the past few hours) should be considered guilty of impaired driving if that person’s BAC is detectably different from zero. All that means is that, if you’ve been toking and drinking, you need to wait as many hours as you’ve had drinks before getting behind the wheel.

Of course, if I were advising someone personally, I’d be much more cautious: driving within six hours of using cannabis is pretty damned stupid. But the same is true of driving after a sleepless night. The question isn’t what’s imprudent; the question is what’s hazardous enough to make a serious criminal offense. So far, the numbers I see about stoned driving (in the absence of alcohol) don’t bring it across that very high threshold.

Given the long latency of THC, the “zero-tolerance” rules now being passed in some states, which making driving with any detectable cannabis on board drugged driving per se, without evidence of actual impairment, are simply a backdoor way of recriminalizing cannabis use.

Footnote A case-control study – comparing a group of drivers responsible for accidents with a random sample of all drivers – is the only way to figure out what’s really going on. The observation that, as cannabis use spreads, more crash-responsible drivers have cannabis on board tells you precisely nothing. After all, if consumption of blintzes were to increase, more responsible drivers would test positive for ricotta. You neeed a denominator, not just a numerator.

Drunk driving, stoned driving, and official lying

Threats to society, in increasing order: (1) stoned driving (2) drunk driving (3) official lying.

As if on cue, the day after I blasted the dishonesty of a group of cannabis advocates, comes Radley Balko to report what appears to be an even more outrageous bit of bamboozlement from the anti-pot side. It now comes out that the “stoned driver” who plowed his truck into a pair of police cars with flashing lights had a blood-alcohol content of .268%, which Balko (or at least his headline-writer) correctly identifies, using the relevant technical vocabulary, as “drunk off his gourd.” (Sometimes read as “drunk out of his gourd,” or the shorter and more graphic “sh*tfaced.”) This driver was at more than three times the legal limit of .08%.

The involvement of alcohol is hardly surprising. Drunk driving is much more dangerous than stoned driving, and the combination is worse than either drug alone.

Yes, Keith Kilbey was also at about double Colorado’s legal limit for THC. But, as Balko points out, it’s virtually impossible to believe that the cops at the scene didn’t notice that the driver was blotto; a Breathalyzer would have been routine under the circumstances. So when state police Cpl. Heather Cobler told reporters that “we believe marijuana” caused the crash, she was almost certainly being … economical with the truth. If I were running the Colorado State Police, Cpl. Cobler would have a whole bunch of ‘splainin’ to do. The credibility of police as witnesses is a key resource for law enforcement; if they routinely lie to reporters, why should jurors believe them?

But the responsibility here goes way above a corporal’s pay-grade; the department should have come forward to correct the story as soon as the toxicology results were in, rather than waiting for others to notice the falsity of the original assertion. It seems to me that reporters in Colorado should be demanding an official explanation of how the misstatement was made, why it wasn’t promptly and frankly corrected, and what institutional steps are being taken to prevent the repetition of such misconduct. Whether reporters ask or not, it’s the responsibility of the department to make the necessary inquiries and take appropriate administrative action. Continue reading “Drunk driving, stoned driving, and official lying”