Fatal Road Crashes Involving Marijuana Double After Legalization

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.

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.

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, and the presence of active THC is generally suggestive of recent marijuana use. These limits are similar in concept to the .08 BAC limit for driving under the influence of alcohol.

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:

• There is no science showing that drivers reliably become impaired at a specific level of marijuana in the blood. Depending 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 behind the wheel. 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.

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.