Higher Risk: Study Claims States That Legalized Marijuana Have More Traffic Accidents

Matt Posky
by Matt Posky

The Insurance Institute for Highway Safety and the Highway Loss Data Institute announced Thursday that auto crashes in states with legalized recreational marijuana have increased 6 percent. Both groups will be on hand at the Combating Alcohol-and Drug-Impaired Driving summit at IIHS’ Vehicle Research Center in Ruckersville, Virginia to present two studies on the issue. Perfect timing, considering Canada just became the second country to legalize the substance and support for decriminalization continues to grow in the United States.

Of course, things are rarely so simple. While the IIHS and HLDI remain confident in their research, the National Highway Traffic Safety Administration claimed marijuana use was unlikely to contribute to traffic mishaps in any meaningful way back in 2015. And that’s just for starters. There is so much conflicting information on this issue, it’ll make your head spin harder than the most savage bong rip of your life, bro.

While there’s no reason to doubt the data from the IIHS, it could also be claimed that it’s in the organization’s best interests to find new ways to elevate insurance rates while simultaneously conducting meaningful crash test research. In this instance, analysts estimated that the frequency of collision claims per year rose a combined 6 percent following the start of legal sale of recreational marijuana in Colorado, Nevada, Oregon, and Washington versus the control states of Idaho, Montana, Utah and Wyoming. That data came via collision loss information collected between January 2012, when recreational sales began for Colorado and Washington, and October 2017.

A separate IIHS study examined police-reported crashes between 2012 and 2016, before and after retail sales began in Colorado, Oregon and Washington. The IIHS estimated the three states combined saw a 5.2 percent increase in the rate of crashes per million vehicle registrations, compared with neighboring states that did not legalize marijuana sales. However, it can’t accurately attribute this to marijuana, just that there is a correlation of some kind — which is important to remember while considering the data.

According to the National Safety Council, countrywide crash rates rose by 6 percent in 2016 and 7 percent in 2015. Framed this way, the pot-smoking states seems to be roughly on par with the national average. See how slippery statistics can be?

Let’s keep playing devil’s advocate and swap sides. Fatalities on U.S. roads fell slightly in 2017 after two years of sizable increases. But on-road deaths in Colorado continued to climb. In fact, 2017 was the worst year for the state since 2004… when it had a significantly smaller population and marijuana wasn’t legal. Swapped again!

We could do this all day. The issue might even come down to some of these state’s incredibly swift population growth. Still, IIHS analysts say they controlled for “differences in the rated driver population, insured vehicle fleet, the mix of urban vs. rural exposure, unemployment, weather and seasonality.” Maybe there is something to this, if they truly managed to nullify any margin of error.

Previous research efforts have strongly hinted that driving under the influence of marijuana is less debilitating than alcohol — not just because THC has less of an affect on fine motor skills, but also because those using it are statically less likely to feel confident in engaging in complex tasks or risk-taking behaviors. Typically, the inverse of this is true when it comes to booze. However, the consumption alcohol is more easily measured and the outward signs of impairment are usually more visible, while the amount of marijuana present in a person’s body doesn’t consistently relate to impairment.

Those earlier studies also indicated that regular pot smokers are less likely to have issues. Despite the demonstrable neurophysiologic impairments associated with THC, studies involving experienced smokers driving on an outdoor course have shown almost no functional impairment under the influence of marijuana — except when combined with alcohol. We covered those studies last year, some of which are highly intriguing, when the IIHS and HLDI claimed that collision frequencies in Colorado, Oregon and Washington were roughly 3 percent higher than what would have been expected without legalization.

This year sees the agencies taking a more serious run at the burning bush. “The new IIHS-HLDI research on marijuana and crashes indicates that legalizing marijuana for all uses is having a negative impact on the safety of our roads,” said IIHS-HLDI President David Harkey. “States exploring legalizing marijuana should consider this effect on highway safety.”

“Despite the difficulty of isolating the specific effects of marijuana impairment on crash risk, the evidence is growing that legalizing its use increases crashes.”

It should be said that driving under the influence of either alcohol or marijuana is totally against the law and not something we condone. Neither substance should be in your system when you take the wheel, regardless of their legal status. But the Insurance Institute for Highway Safety seems to be taking things a step further by subtly suggesting that states might want to think twice about decriminalizing recreational pot. Following that logic, it seems they’d probably want to push for the prohibition of alcohol as well.

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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  • Kamiller42 Kamiller42 on Oct 23, 2018

    Increasing accessibility, and therefore usage, to a psychotropic drug increases accidents? Anyone really surprised?

  • Zipper69 Zipper69 on Apr 23, 2020

    Real men get plastered - right?

    • -Nate -Nate on Apr 23, 2020

      Getting plastered is fine, just DO NOT DRIVE NOR RIDE when you are . Pretty simple unless you're a mouth breather . -Nate

  • Lorenzo Subaru had the ideal wagon - in 1995. The Legacy Outback was a straight two-box design with rear quarter and back windows you could see out of, and was available in brown with a 5-speed manual, as God and TTAC commenters intended. It's nice they're not raising prices, but when you've lost the plot, does it matter?
  • Bkojote Remember a month a go when Cleveland wanted to create a more walkable Cleveland and TTAC's 'BIG GOVERNMENT IS THE PROBLEM' dumbest and dullest all collectively crapped their diapers? Here's the thing- look on any American highway and it's littered with people who don't /want/ to be driving or shouldn't be. Look at every Becky on her phone during the morning commute in her Tucson, look at every Brad aggro driving his 84 month loan GMC. Hell look how many drivers nowadays can't even operate a headlight switch. You expect these people to understand a stoplight? In my neighborhood alone 4 people have been rear ended at lights from someone on their phone. Distracted driving over the past 10 years has spiked, and it's only going to get worse unless Becky has an alternative, because no judge is going to pull her license when 'she needs it to get to work!' but heaven forbid she not check fb/tiktok for 40 minutes a day.
  • Scott Shouldn't the The Italian Minister for Business be criticizing The Milano for being too ugly to be Italian?Better use of resources doing that....
  • Steve Biro Frankly, while I can do without Eyesight and automatic start-stop, there is generally less B-S with Subarus in terms of design, utility and off-road chops than with many other brands. I just hope that when they adopt Toyota’s hybrid system, they’ll also use Toyota’s eCVT.
  • The Oracle These are all over the roads in droves here in WNC. Rarely see one on the side of the road, they are wildly popular, capable, and reliable. There is a market for utilitarian vehicles.
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