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.

Research Results:

The Foundation examined drug tests and fatal crashes among drivers in Washington, which became one of the first two states to legalize recreational use of marijuana in December, 2012. Researchers found:

• The percentage of drivers involved in fatal crashes who recently used marijuana more than doubled from 8 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 involving marijuana is alarming,” said Peter Kissinger, president and CEO of the AAA Foundation for Traffic Safety. “Washington serves as an eye-opening case study for what other states may experience with road safety after legalizing the drug.”

Marijuana Legalization:

To date, 24 states have legalized marijuana for therapeutic and medicinal use. Four of those states, Alaska, Colorado, Oregon and Washington, along with Washington D.C., have also legalized recreational use of the drug. With at least 20 states, including Ohio, considering marijuana legalization this year, these findings raise serious concerns about drug-impaired driving.

Problems With Setting Limits;

In an attempt to enforce drug-impaired driving, some states have created legal limits, also known as per se limits, which specify the maximum amount of active THC that drivers can have in their system based on a blood test. THC is the main chemical component in marijuana that can impair driver performance and affect the mind. These limits are similar in concept to the .08 BAC limit for driving under the influence of alcohol. Ohio has a per se limit of 2 ng/mL.

Researchers have examined the lab results of drivers arrested for impaired driving, and the results suggest that legal limits for marijuana are problematic because:

• There is no science showing that drivers reliably become impaired at a specific level of marijuana in the blood. Impairment depends on the individual. Drivers with relatively high levels of marijuana in their system might not be impaired, while others with low levels may be unsafe to drive. This is very different from alcohol.

• High THC levels may drop below legal thresholds before a test is administered. 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.

• Marijuana can affect people differently. For example, frequent users of marijuana can exhibit persistent levels of the drug long after use, while drug levels 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 Marshall Doney, AAA president and CEO. “In the case of marijuana, this approach is flawed and not supported by scientific research.”

Solutions to Combating Marijuana-Impaired Driving:

Rather than relying on arbitrary legal limits to improve road safety, AAA urges states to use a two-component system that requires:

1. A positive test for recent marijuana use.

2. And most importantly, behavioral and physiological evidence of driver impairment.

This system relies 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.

Whether the use of marijuana is legal or not, all motorists should avoid driving while impaired to avoid putting themselves and other road users at risk. Just because a drug is legal does not mean it is safe to use while operating a motor vehicle. For example, there are many over-the-counter drugs that can cause driver impairment.

Visit AAAFoundation.org for more information on this and other research.