Letter to the Editor: Absolutism on Marijuana and Driving is a Fool's Folly

Dear Editor:

Regarding comments to the Patch article

Ken James--please, PLEASE! point to a post where I have stated that impaired driving is anything less than impaired driving. I have taken you to task for misrepresenting conclusions in science papers. Like you, I would like to drive on a roadway where all drivers are at 100% of their competency level, which in my opinion is still pretty low. But, it generally works that those with higher skill levels at any moment help to keep mistakes from lower skill-level drivers causing destruction. With so many crappy drivers on the road, there are still problems. <thisIsSarcasmKen>I know when I want to drive impaired, I just wear my hat with a phony cell phone and hand hanging on the left side. The cops see me, and say, "Oh, he’s okay; he’s just on the cell phone."</thisIsSarcasmKen>

Ken James' hypothesis seems to be that with legalized marijuana, there will be a significant increase of impaired (stoned) drivers on the road. If this hypothesis is correct, then the question of degree of impairment becomes important. It appears that some reputable studies have concluded that risk of serious accidents double at some level of MJ intoxication. Buying a second lottery ticket doubles your chances of winning the lottery. The initial probabilities are important, though, as to the total likelihood of winning the lottery or being in a crash. Joint probabilities increase when multiple impaired drivers are in the same roadway sections.  Also germane to Ken James’ argument, and related to a point that other commenters have tried to make, is whether MJ use is fungible with alcohol use, or additive. In other words, does the number of impaired people (likely to drive) cluster around a mean value, or will there be an irruption of impaired people as apparently hypothesized by KJ?

Others are arguing that some intoxicants decrease motor skills less than others, which Ken James might or might not dispute. Let us assume it is true, certainly there are studies to support that position. Then, if the numbers of impaired drivers cluster about a mean, but some of those drivers choose a less-impairing drug, then there might actually be some improvement in traffic statistics. Of course, the converse is also possible if people move to higher impairment drugs.

Let’s hypothesize that stoners drive more slowly than boozers, again supportable by some studies. In any case, energy is proportional to the square of velocity.  If, in a 40 mph zone a stoner drives, say, 35 mph, then the energy to dissipate by braking, or crashing, is about 77% of the speed limit energy. If instead, the impaired driver drives at 45 mph in a 40 mph zone, energy is about 127% of that posted, resulting in significantly more damage in a crash. 60/40-->225%.

So, an interested reader will note that there are multiple parameters that can interact to make it difficult to state precisely what driving impacts will accrue from the legalization of marijuana. Additionally, if there is an increase in MJ users as a result of legalization (among law-abiding (formerly unimpaired) drivers), then those same new users that obeyed past laws are likely to continue obeying the law, and unlikely to drive impaired, leaving probabilities unchanged (my supposition, not assertion of fact).

Ken James’ absolutism is a fool’s folly. His aspersions and projections regarding my statements are unacceptable.  Likewise, those who make absolute claims opposite to Ken James’, may not yet have definitive unbiased peer-reviewed studies. The word ‘prove’ is a bit strong for either side to use, as regards traffic outcomes.  

All probabilities aside, in spite of terrible odds, people win the lottery, unimpaired drivers kill each other, impaired drivers kill, and impaired and unimpaired drivers make it home to face the odds again. As I noted in my piece "What do you fear?," no one can guarantee that an event with non-zero probability will not occur. Nor, can anyone guarantee that an event with probability less than one will occur. We apply our best guess, based on the p.

As for me, the aircraft carrier didn’t kill me, and I don’t plan to let a cell phone or texting driver, stoner, drunk, angry jerk listening to talk radio, or a driver stringing a tennis racquet (yes, I’ve seen that, too) kill me either. In fifty years of accident-free driving, I’ve avoided converting other drivers’ mistakes to accidents, and I’ve made mistakes that someone else bailed me out of. The best I can say is to “drive safely, and give it 100%,” even though your 100% is probably crappy by my standards (but I hope not).

Sincerely,

Bob McCoy

Sammamish