Motor1’s man about town does not imbibe and drive, but he does raise some fair points about our changing legal landscape.

I’ll admit it. I’ve inhaled. It was perfectly legal, enjoyable, and Pink Floyd never sounded better.

But I’ve never driven high. I treat marijuana much like its sloppier and more belligerent brother, alcohol, and don’t mix either with any activity that puts me behind the wheel of a car.

Apparently, I am not alone. After all of the dire warnings of high drivers causing mayhem on America’s roadways (likely en route to grocery stores to buy mac and cheese) after states legalized marijuana, the apocalyptic driving never materialized. In fact, a recent study by Columbia University’s School of Public Health shows that fatal accidents have gone down in those states (as detailed in our first story in this series).

So is pot punching a hole in traffic fatalities and making America’s roads safer?

Much like rolling a joint with one hand: it’s complicated. Correlation does not mean causation. But the numbers inside the study are interesting. Looking back over the past 30 years, traffic deaths dropped 11 percent on average in states that legalized marijuana. Over the same time, traffic deaths dropped 12 percent for those between 25 and 45 years old – the group with the largest percentage of registered marijuana users.

Looking back over the past 30 years, traffic deaths dropped 11 percent on average in states that legalized marijuana.


Other studies have shown big drops in traffic fatalities immediately following a state’s legalization of medical marijuana, but then those numbers slowly climbed back up over time.

Theories abound as to why this phenomenon occurs. It could be that people stop going to bars and instead stay home with a few spliffs and a case of Doritos. Others speculate that an increased police presence prior to legalization creates a strain of paranoia that keeps those who use marijuana off the roads. Still more say that users are well aware of their incapacitating effects of marijuana so they stay off the road when they might not have similar judgement after drinking. Occam’s razor might cut through the speculation and show that Uber and Lyft’s popularity have helped curb traffic fatalities.

Of course, the real reason traffic fatalities have dropped in states with legal weed could very well be that many marijuana users simply can’t find their shoes, much less their car keys.

However, not all of the numbers are as optimistic. The National Highway Traffic Safety Administration found that 12.4 percent of fatal crashes in Colorado involved someone who tested positive for only marijuana. (At the same time, the study, which looked at 2013 and 2014 statistics, found that DUIs have dropped considerably as well.) In Washington, the AAA Foundation for Traffic Safety found that fatal crashes involving someone who had used weed doubled, rising to 17 percent of all fatalities after legalization.

Furthermore, there remain problems for police attempting to enforce driving-while-impaired laws. Stoned drivers are likely easy for police to identify, as they travel along at 12 miles per hour and, after they are pulled over, endlessly stare into the flashing lights behind them. Giggling when the officer says words like “pull” or “detained” doesn’t help.

Using marijuana does affect a person’s motor skills and judgement, but a debate remains at what level and how to measure if a person is under the influence while they are driving.


However, there is no clear testing method for whether or not a person is actually high while they are driving. Traditional breathalyzers cannot detect THC, the magical chemical that causes time to slow down and turns your body into a gummy bear. Mmmm, gummy bears.

Police can demand blood or urine from the driver (you have already consented to these searches by signing for your driver’s license). A popular saliva test, which also tests for other drugs, is arguably less intrusive than a police officer holding a syringe, but still only detects the presence of THC. Those tests cannot definitively say when a person smoked, ate, or, otherwise, got high.

THC can stay in a person’s system for weeks after it is ingested. That means a person could get high in the comfort of their own home on Saturday while watching a Beavis and Butthead marathon, get pulled over weeks after that, and still test positive for THC long after the effects of marijuana have passed. Are they impaired? Heh, heh, heh, heh, heh, no.

One issue appears to be that the alcohol model, measuring a certain amount in the blood, is not exactly the same as measuring the amount of THC in a person. Using marijuana does affect a person’s motor skills and judgement, but a debate remains at what level and how to measure if a person is under the influence while they are driving.

Driving stoned is stupid and potentially deadly. Driving drunk is stupid and dangerous. Texting and driving is stupid and dangerous. But legalized weed has not brought us to the end of the world. Instead, it has produced some unexpected results that require additional research. And if researchers are loaded up with some Chem Dog or Sour Kush and need some volunteers for additional testing, send me a note.


--
Scott Burgess has covered the auto industry for more than a decade as The Detroit News' auto critic and as Detroit Editor at Motor Trend. Before writing about cars and the people who make them, he was a newspaper journalist, where he covered everything from small town politics to the wars in Afghanistan and Iraq.

Read more from Scott:

Be part of something big