Fatal Crashes Involving Drivers Who Test Positive for Marijuana Increase After State Legalizes Drug

Percent of THC-positive drivers has doubled since recreational use was legalized

01/30/20 | Legislative, Traffic Safety

MINNEAPOLIS, MN (Jan. 30, 2020) – A concerning number of Washington state drivers involved in fatal crashes are testing positive for recent use of marijuana, according to new research from the AAA Foundation for Traffic Safety.

The share of drivers who, after a fatal crash, tested positive for active THC – the drug’s main psychoactive ingredient – has doubled since the state legalized marijuana in December 2012. AAA believes the increase raises important traffic safety concerns for drivers across the country, because recreational marijuana use is now legal in 11 states and Washington, D.C.

Between 2008 and 2012 – the five-year period before the drug was legal – an estimated 8.8% of Washington drivers involved in fatal crashes were positive for THC. That rate rose to 18% between 2013 and 2017.

The average number of THC-positive drivers increased, too. In the five years before legalization, an average of 56 drivers involved in fatal crashes each year were THC-positive. In the five years after legalization, the average jumped to 130. The new numbers bolster the findings of a similar report the AAA Foundation released in 2016. The study did not attempt to determine if marijuana contributed to the crashes included in its latest research. It focused only on the prevalence of drivers who tested positive for active THC.

“This study enabled us to review a full 10-years’ worth of data about the potential impact of marijuana on driving safety – and it raises significant concerns,” said Dr. David Yang, executive director of the AAA Foundation for Traffic Safety. “Results from the analysis suggest that legalization of recreational use of marijuana may increase the rate of THC-positive drivers involved in fatal crashes.”

• inhibit concentration,
• slow reaction times, and
• cloud judgment.

Its effects vary by individual, but a number of studies have concluded that marijuana use impairs the ability to drive safely. Previous research suggests that users who drive high are up to twice as likely to be involved in a crash.

Eleven states and Washington, D.C. have legalized marijuana for both recreational and medical use. Another 22 states have legalized it for medical use only. State legislative sessions for 2020 are getting underway and recreational use is expected to be a popular topic. The legislative interest combined with likely November ballot measures could result in additional states taking a hard look the issue.

In an attempt to curtail drug-impaired driving, seven states have set legal non-zero, or “per se,” limits on the amount of THC drivers can have in their system. While well-intended, AAA believes imposing such limits is problematic because no data reliably shows what level of THC impairs driving, the chemical’s effects vary by user, and THC testing often cannot be done until hours after a crash.

They should adopt a two-pronged approach that requires:

1. a positive test for recent marijuana use
2. behavioral and physiological evidence of driver impairment

Regardless of the drug’s legal status – and limits in any state – all motorists need to avoid driving while impaired.

“Simply put, if you’ve used marijuana, don’t drive,” said Jake Nelson, AAA’s director of traffic safety advocacy and research. “And if you plan to drive, don’t use marijuana.”

Last year, a Foundation survey found that nearly 70% of Americans think it’s unlikely a driver will get caught by police for driving shortly after using marijuana. The survey also revealed that an estimated 14.8 million drivers report getting behind the wheel within one hour after using marijuana in the past 30 days.

AAA is committed to educating the public about the risks of substance-impaired driving. Through AAA Foundation research, AAA is working to improve understanding on the topic and is working collaboratively with safety stakeholders to reduce the impact of substance-impaired driving related crashes.