AAA says marijuana use can lead to fatal crashes but blood test is flawed

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.

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.

The Foundation examined drug tests and fatal crashes among drivers in Washington. 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 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.”

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

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, AAA said.

According to AAA:

• There is no science showing that drivers reliably become impaired at a specific level of marijuana in the blood.
• High THC levels may drop below legal thresholds before a test is administered to a suspected impaired driver.
• Marijuana can affect people differently, making it challenging to develop consistent and fair guidelines.

“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’s president and CEO. “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 is urging states use a two-part system instead of an arbitrary legal limit – a test for recent marijuana use and behavioral and physiological evidence of driver impairment.  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.

“Marijuana can affect driver safety by impairing vehicle control and judgment,” Doney said. “States need consistent, strong and fair enforcement measures to ensure that the increased use of marijuana does not impact road safety.”