Information from AAA
TAMPA, Fla. – Fatal crashes involving drivers who recently used marijuana doubled in Washington after the state legalized the drug, according to the latest research by the AAA Foundation for Traffic Safety.
New research also shows that legal limits for marijuana and driving are arbitrary and unsupported by science, which could result in unsafe motorists going free and others being wrongfully convicted for impaired driving.
Washington was one of the first two states to legalize the recreational use of marijuana, and these findings raise serious concerns about drug-impaired driving with at least 20 states considering marijuana legalization this year.
"AAA does not take a position on the legalization of marijuana, but is passionate about laws ensuring the safety of the motoring public," said Kevin Bakewell, Senior Vice President and Chief Public Affairs Officer for AAA – The Auto Club Group. "Given the findings of this new research, our advice is that nobody should drive after recent marijuana use, and law enforcement should have a fair and educated approach for dealing with those who do."
The Foundation examined drug tests and fatal crashes among drivers in Washington, a state that legalized marijuana in December 2012. The researchers found:
- The percentage of drivers involved in fatal crashes who recently used marijuana more than doubled from eight to 17 percent between 2013 and 2014.
- One in six drivers involved in fatal crashes in 2014 had recently used marijuana, which is the most recent data available.
"The significant increase in fatal crashes with marijuana present is definitely a cause for concern," said Matt Nasworthy, Traffic Safety Consultant for AAA – The Auto Club Group. "These findings make it all the more critical that we continue to research ways to enforce impaired driving scientifically, not simply by using an arbitrary number."
Researchers examined the lab results of drivers arrested for impaired driving, and the results suggest that legal limits for marijuana and driving are problematic because:
Depending on the individual, drivers with low levels of THC in their blood may be unsafe behind the wheel, while others with relatively high levels might not be impaired. This finding is very different from alcohol, where it is clear that crash risk increases significantly at higher BAC levels.
High THC levels may drop below legal thresholds before a test is administered to a suspected impaired driver. The average time to collect blood from a suspected driver is often more than two hours because taking a blood sample typically requires a warrant and transport to a facility. Active THC blood levels may decline significantly and could drop below legal limits during that time.
Marijuana can affect people differently, making it challenging to develop consistent and fair guidelines. For example, frequent users of marijuana can exhibit persistent levels of the drug long after use, while drug levels can decline more rapidly among occasional users.
"There is understandably a strong desire by both lawmakers and the public to create legal limits for marijuana impairment, in the same manner as we do with alcohol," said Bakewell. "In the case of marijuana, this approach is flawed and not supported by scientific research. It's simply not possible today to determine whether a driver is impaired based solely on the amount of the drug in their body."
AAA urges states to use more comprehensive enforcement measures to improve road safety. Rather than relying on arbitrary legal limits, states should use a two-component system that requires (1) a positive test for recent marijuana use, and most importantly, (2) behavioral and physiological evidence of driver impairment. This system would rely heavily on two current law-enforcement training programs: Advanced Roadside Impaired Driving Enforcement (ARIDE) and the 50-state Drug Evaluation and Classification (DEC) program. These programs train law enforcement officers around the country to more effectively recognize drug-impaired driving.
"Marijuana can affect driver safety by impairing vehicle control and judgement," continued Nasworthy. "Just because a drug is legal does not mean it is safe to use while operating a motor vehicle. Drivers who get behind the wheel while impaired put themselves and others on the road at risk."
Four states, including Alaska, Colorado, Oregon, Washington and Washington, D.C., have legalized the recreational use of marijuana, and 20 states have legalized it for therapeutic and medicinal use. Montana and Washington have implemented a per se limit for marijuana at 5 ng/mL; Nevada and Ohio have set a limit at 2 ng/mL; and Pennsylvania's is set at 1 ng/mL.
Twelve states have strict per se laws that forbid the presence of any levels of marijuana. In Colorado, a blood concentration of 5 ng/mL or more gives rise to permissible inference that a person was driving under the influence of the drug.
The AAA Foundation for Traffic Safety will release additional studies later this year that will focus more on marijuana impaired driving and the data collected.