With more states legalizing recreational marijuana use, people worry that more drivers under the influence of pot will lead to an increase in traffic deaths. Researchers have studied the effects of driving under the influence of marijuana and it seems a bit hazy.
The effects of driving while high on marijuana are slower decision making, decreased peripheral vision and impeded multitasking. Unlike alcohol, drivers who are high tend to be aware they are impaired and try to drive slower and avoid risky situations like passing other cars and allow extra room between vehicles.
The combined effects of marijuana and alcohol appear to eliminate the pot smoker’s over-cautiousness and increases the driver’s impairment.
In Washington, there was a jump of nearly 25% in drivers testing positive for marijuana in 2013 but no corresponding increase in car accidents or fatalities. That was after the first full year of legalization for recreational use.
When a driver has alcohol in their system it is easy to test on the spot with a breathalyzer. THC, the active ingredient in marijuana, can linger in the body for days or weeks and can only be found through blood or urine tests. This makes it harder for safety officials to test drivers who they suspect are high. Typically 12% of drivers randomly stopped on a Friday or Saturday night had been drinking and only 6% tested positive for marijuana use.
Inexperienced users of marijuana are more likely to be impaired while driving than those who are habitual smokers. Some studies show almost no driving impairment in habitual smokers.
Many states do not test drivers involved in a fatal crash for drugs unless there is a reason to suspect they may have been under the influence. If a driver tests positive for alcohol, there is typically no further testing of other substances because alcohol alone may be enough to bring criminal charges.
Driving while high on marijuana is still illegal in all states and drivers can face criminal charges if found impaired. The overall effects of marijuana show that someone driving high is less likely to be involved in an accident than someone driving under the influence of alcohol.