Brian Palmer discovers that it’s an open and shut case, for Slate:
A new study suggests that legalizing medical marijuana reduces traffic fatalities. The authors noted that legalizing marijuana reduces alcohol consumption, and people are more wary of driving high than drunk. Which drug is actually more dangerous on the road?
Alcohol, and it’s not even close. It’s hard to directly compare alcohol and marijuana, because driving impairment depends on dosage and the two drugs tend to affect different skills. (Pot makes drivers worse at mindless tasks like staying in a lane, while alcohol undermines behaviors that require more attention like yielding to pedestrians or taking note of stop signs.) Nevertheless, Yale psychiatrist Richard Sewell reviewed the academic literature on driving while intoxicated in a 2009 article, and found that alcohol is significantly more dangerous. Real-world data from auto accidents indicate that a drunk driver is approximately 10 times more likely to cause a fatal accident than a stoned driver.