Wrong-Way Driver, Wrong Argument

The St. Paul Pioneer Press has a Saturday feature on its editorial page called "Sainted and Tainted," in which readers send in their thanks to people and businesses who have performed random acts of kindness or, conversely, people who didn't do the right thing when human decency would dictate they should have.

Last weekend there was a Tainted letter from a person who said they were walking on a bike/pedestrian shared-use path after dark with their dog, when a car came driving toward them. Yes, the car was being driven illegally on a bike/pedestrian path. 

The driver stopped and got out of the car, apologized, and then backed out of the bike/ped path.

I have seen my share of drivers on bike paths, so the car's presence did not surprise me generally. The fact that the driver stopped and apologized was what surprised me.

But then the letter took a turn. The writer said that when the car's door opened, they smelled marijuana wafting out of the interior. They pointed out that during their walk, they had been wearing reflective clothing and their dog had on an LED light, and if they hadn't been so visible to this impaired driver, what would have happened? Would they have been run over?

The writer then used this case to decry the fact that Minnesota's legislature is moving toward legalization of marijuana. 

And that's where they lost me.

Their point seems like an argument for banning alcohol, since it's more likely to be the culprit in wrong-way driving like this…But we know banning it does not work, given how Prohibition went. 

This did make me curious about what the data say about the effect of legalization on driving in states that have already legalized marijuana.

Here's one study covering five years of data from Washington and Colorado, which found an increase in fatal crashes, but not a statistically significant one. (What do they mean by not statistically significant? 1.2 more fatal crashes per billion vehicle miles traveled.)

This article, despite all the alarmist words like "spike" and "jump," contains this statement:

...preliminary results of a...study of injured drivers who visited emergency rooms in California, Colorado and Oregon showed that drivers who used marijuana alone were no more likely to be involved in crashes than drivers who hadn’t used the drug. That is consistent with a 2015 study by the National Highway Traffic Safety Administration that found that a positive test for marijuana was not associated with increased risk of being involved in a police-reported crash. (emphasis added)

So fatal crashes, and crashes where the driver was injured enough to go to an ER, and crashes that were reported to the police... None of those turned up anything statistically significant for marijuana use alone in multiple states that had legalized. 

How likely is that to be true about alcohol?