The push for marijuana legalization seems to be gaining steam, with even the Monkey Cage Blog asking whether pot was the new gay marriage, meaning solely that the trend lines in polling around the country were starting to cross, with a majority supporting it rather than a majority opposing it (The American Prospect denies that it’s that important, though, at least politically). The New York Times Editorial board published a piece today citing research by Dan Rees of Colorado-Denver and Mark Anderson of Montana State to support the idea that marijuana and alcohol are substitutes, which means good things for road safety.
Logic: more marijuana use means less alcohol use means less driving drunk and more driving high, and driving high is safer than driving drunk.
While it’s odd in and of itself to herald impaired driving (even if it’s in comparison to even-more-impaired driving), I’d question whether we knew all that much, in a scientific sense at least, about driving high. Surely, it happens all the time (I’m from Colorado, people, I know it’s happening and so do you), but it’s not clear that those who would drive drunk see marijuana as a substitute and thus would drive high instead. There’s been no evidence presented that the specific group of those with a propensity to drive drunk sees marijuana as a substitute, which is the key to the road safety argument.
Secondly, the Rees & Anderson paper says “there is evidence that drivers under the influence of THC compensate for these impairments. For instance, they tend to drive slower and take fewer risks.” Admittedly not having read the studies they cite, I’m curious whether these drivers are being more careful and following less closely because marijuana makes them more relaxed and in less of a hurry, or because the consequences of getting caught are higher. Legalizing marijuana would eliminate the second concern, taking road safety off the pro-legalization side. It may be that THC itself induces the behavior, but I’m not convinced by these logical leaps.