Given Montana's relatively bad traffic fatality statistics, it seems to me that we can't promote legal recreational marijuana use without at least understanding what impact it might have on public safety on the highways. And in that regard the statistics cited by Pew in a new report might give us pause. But I have my doubts about how useful they are.
Essentially, what Colorado, Washington and other states that have legalized recreational use are reporting is a pretty big increase in the number of drivers who were using (or had recently used) marijuana when they got killed in an accident. That's suggestive, but it doesn't prove much. What we really want to know is whether, when you smoke a joint or pop an edible and get behind the wheel, you’re more likely than you otherwise would be to end up killing yourself or somebody else. And the way to answer that question is to compare the fatal accident rate for all the drivers who are under the influence of marijuana with that of all the drivers who aren't under the influence of anything. Even that comparison could be misleading, of course, because the universes of using and non-using drivers may differ from one another in some relevant respect, such as age. That's a typical confounding variable problem, and it needs to be accounted for, but in any case, we don't have the data needed to make the comparison in the first place.
That doesn't mean that the question can be ignored. Pew reports that in 2016, of all the fatally injured drivers tested, 38 percent tested positive for marijuana use alone (the issue gets a lot more complicated when you have to take into account cases where the driver was using marijuana and drinking, or using other drugs, at the same time). On the assumption that drivers are usually tested when there is some reason to suspect they were impaired, the rate of marijuana use among all fatally injured drivers is probably less than 38 percent. That may yet sound pretty high, but whatever it is, we still don't know how it compares to the rate of use among drivers who don't have fatal accidents. It would surprise me if 38 percent of all the drivers out on the road tested positive, but what do I know? And as Pew points out, coming up with the right data is further complicated by the fact that drivers can "test positive" for marijuana long after any effects that would affect driving have worn off.
I doubt that in what remains of my political career (one more session in the Montana Senate) I will ever have the opportunity to vote on legalization, so my opinion doesn't count for much. But for what it's worth, it seems to me that decriminalization is a no-brainer. It's a monumental waste of time and resources to pursue, arrest, convict and incarcerate people for smoking a little reefer. When it comes to full on, Colorado style legalization, however, and particularly the promotion of recreational use, I have some some concerns - about public safety, for one thing, and about the health impacts of the very powerful marijuana available in the shops, for another. And the last thing in the world I think we should do is legalize because we can then collect a boatload of tax dollars. We shouldn't make ourselves financially dependent on the sale of a product that may turn out to be a stone around our necks. We did that with coal, and you can see how that worked out.