IIHS Claims Marijuana Legalization Causes Crashes

Matt Posky
by Matt Posky

It’s always nice to get a break from the endless stream of industry marketing materials about electrification, though this week’s impromptu theme still involves going green. Following news that General Motors is considering changing its drug testing policies to exclude marijuana, there has been heavy coverage of an Insurance Institute for Highway Safety (IIHS) study claiming states that have legalized recreational use of cannabis are seeing more crashes.

But the framing seems wildly irresponsible as it fails to highlight the problem being heavily tied to individuals operating a vehicle under the influence of marijuana and alcohol combined. It’s more or less what the IIHS attempted to do in 2018 with help from the Highway Loss Data Institute (HLDI). Our guess is that the duo is seeking out fresh reasons for insurance companies to raise rates in regions that have legalized pot because even their own research complicates the issue.

Their latest data suggests that legalization and retail sales of cannabis in California, Colorado, Nevada, Oregon, and Washington resulted in a 6 percent increase in injury crash rates and a 4 percent increase in fatal crash rates compared with other Western states where pot was illegal at the time of the study. The IIHS and HLDI have actually conducted a series of studies since 2014, with the outcome often the same. But it’s at odds with a study released by the National Highway Traffic Safety Administration in 2015, which came to the conclusion that THC wasn’t contributing to an increase in accidents.

Independent tests and surveys have been a mixed bag. The majority seem to agree that cannabis consumption typically slows driver reaction times and makes it harder to focus. But regular users don’t tend to suffer from these side effects and the abundance of caution THC hilariously might make some stoners better drivers. Simulations have likewise shown them to be less likely to speed or act aggressively in traffic and they typically increase following distances (something the IIHS noted). There are even instances where testing has shown subjects declining to get behind a wheel in a real-world setting, after stating they didn’t feel comfortable driving high.

There’s been no consensus on whether or not smoking pot makes you a menace behind the wheel but the early data seems to suggest not. So then why are the IIHS and HLDI claiming otherwise? Because they can incorporate alcohol on the sly.

In fact, the latest from those outlets used data collected from injured drivers visiting emergency rooms in Sacramento, California; Denver, Colorado; and Portland, Oregon — none of which represented an increased risk associated with marijuana unless it was combined with booze. Of the 1,200 people examined, none of the drivers that tested positive for smoking weed were injured at a higher rate than those who were sober. But the ones that were drinking and also decided to puff the magic dragon did see elevated numbers.

This isn’t a recommendation to get stoned and hop into a vehicle. We wouldn’t advise using any mind-altering substance to someone preparing to drive an automobile and being sober offers some pretty clear tactical advantages. However, the framing of these studies is often misleading and unhelpful in terms of deciding future legislation in a truly effective manner.

If you’re hoping for an outlet that actually seems interested in getting to the bottom of things without a lot of spin, the American Automobile Association (AAA) has frequently shown itself capable of nuance. It’s looked into the issue to and decided that the most serious issue is likely people partying themselves into oblivion using a variety of substances. The AAA Foundation’s annual Traffic Safety Culture Index found that drivers who use both marijuana and alcohol “ were significantly more prone to driving under the influence of alcohol alone versus those who only drink alcohol but do not use marijuana.

The outlet also made it clear that it does not support the “legalization of recreational marijuana because of its inherent traffic safety risks and the difficulties in writing legislation that protects the public and treats drivers fairly.” It apparently just sees boozing as the bigger issue and full-on partying behind the wheel as the worst-case scenario for motorists. It’s an interesting report and well worth reading for the added context and rather clear statistical information.

But that doesn’t make the IIHS content totally worthless. Despite our criticizing the group for framing the issue in a specific manner, those who bother to read the entirety of their article still end up learning that alcohol plays a significant factor. It even references the above AAA report and eventually suggests that disparities in state and local regulations might be influencing driver behaviors and the tabulated data. We’re just annoyed that it makes these sweeping assertions using somewhat specious reasoning and limited information. No study appears to have a handle on exactly how much cannabis consumption impairs motorists and most of the data we’ve seen seems to indicate it varies wildly from person to person. Knowing that simply has not stopped the IIHS from jumping to conclusions.

“Our latest research makes it clear that legalizing marijuana for recreational use does increase overall crash rates,” IIHS-HLDI President David Harkey said in a statement. “That’s obviously something policymakers and safety professionals will need to address as more states move to liberalize their laws — even if the way marijuana affects crash risk for individual drivers remains uncertain.”

Policymakers and safety professionals have been placed on notice. Even though there are still glaring questions surrounding the matter, it’s time for them to address these issues as the scourge of hypothetical dope fiends revving their engines in a fit of refer madness is upon us.

[Image: Mitch M/Shutterstock]

Matt Posky
Matt Posky

A staunch consumer advocate tracking industry trends and regulation. Before joining TTAC, Matt spent a decade working for marketing and research firms based in NYC. Clients included several of the world’s largest automakers, global tire brands, and aftermarket part suppliers. Dissatisfied with the corporate world and resentful of having to wear suits everyday, he pivoted to writing about cars. Since then, that man has become an ardent supporter of the right-to-repair movement, been interviewed on the auto industry by national radio broadcasts, driven more rental cars than anyone ever should, participated in amateur rallying events, and received the requisite minimum training as sanctioned by the SCCA. Handy with a wrench, Matt grew up surrounded by Detroit auto workers and managed to get a pizza delivery job before he was legally eligible. He later found himself driving box trucks through Manhattan, guaranteeing future sympathy for actual truckers. He continues to conduct research pertaining to the automotive sector as an independent contractor and has since moved back to his native Michigan, closer to where the cars are born. A contrarian, Matt claims to prefer understeer — stating that front and all-wheel drive vehicles cater best to his driving style.

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  • Bachewy Bachewy on Jun 19, 2021

    Sigh, again, another 'study' with not enough data. There is still no test that can prove impairment by marijuana after an accident. It's a judgment call by the cops on the scene. So again they say, "well since pot is legal and wrecks went up, pot is causation' without looking at other factors such as population increase (which results in more wrecks simply due to statistics per capita). Sure, one shouldn't high and drive, but don't penalize entire states just to get more $$$ when the majority of people in those states do not get high, even after legalization.

    • Lou_BC Lou_BC on Jun 19, 2021

      In Canada one study showed similar results. There was an increase in crashes where cannabis and alcohol were consumed together. Cannabis is subsequently being demonized. Ironically, the one study was cosponsored (i.e. funded) by "Beer Canada", an association representing beer manufacturers. A lobby group for beer spits out a report indicating that cannabis is bad.. hmmmm....

  • Jeff S Jeff S on Jun 19, 2021

    Politicians use to promise a chicken in every pot now it is pot in every chicken.

  • Lou_BC As others have pointed out, some "in car" apps aren't good or you pay for upgrades. My truck did not come with navigation. It was an expensive option. There's a lame GM maps app that you need to subscribe to "in-car" data. The map does not give you navigation other than to tell you where restaurants and gas stations are located. I'd want Android auto since I already pay for the phone.
  • Theflyersfan Given so many standard nav systems aren't the best and updating could mean a dealer trip, and I stream all music, Android Auto is an absolute must. Wireless isn't necessary and some wireless chargers overheat the phone. And there are some hacks that let YouTube stream on the screen - excellent for listening to concerts.
  • Jeff I going to guess by the condition of the body and interior that there is little to no rust on the frame. Appears to be a very well maintained car.
  • MaintenanceCosts Would not buy a new daily car without it.
  • Namesakeone I hate the thought, and I hope I'm wrong. Mazda. They're a small fish in a really big pond, and they made their reputation on sports cars--a market segment that nobody seems to want to buy new anymore.