Marijuana Impairs Driver's
There are many misconceptions about marijuana use, including rumors that marijuana can’t impair you or that marijuana use can actually make you a safer driver.
Several scientific studies indicate that this is false. Research shows that marijuana impairs motor skills, lane tracking and cognitive functions (Robbe et al., 1993; Moskowitz, 1995; Hartman & Huestis, 2013). A 2015 study on driving after smoking cannabis stated that THC in marijuana also hurts a driver’s ability to multitask, a critical skill needed behind the wheel.
NHTSA continues to conduct research to better understand the relationship between marijuana impairment and increased crash risk. NHTSA’s Drug and Alcohol Crash Risk Study found that marijuana users are more likely to be involved in crashes. However, the increased risk may be due in part because marijuana users are more likely to be young men, who are generally at a higher risk of crashes.
In 2020, research indicated drug prevalence is on the rise among drivers. NHTSA’s study of seriously or fatally injured road users at studied trauma centers (Thomas et al., 2020) suggested that the overall prevalence of alcohol, cannabinoids and opioids increased during the public health emergency compared to before. Between mid-March and mid-July 2020, almost two-thirds of drivers tested positive for at least one active drug, including alcohol, marijuana or opioids. The proportion of such drivers testing positive for opioids nearly doubled after mid-March 2020, as compared to the previous six months, while marijuana prevalence increased by about 50%.
While evidence shows that drug-impaired driving is dangerous, we still have more to learn about the extent of the problem and how best to address it. In January 2018, NHTSA launched a new initiative to address drug-impaired driving. NHTSA’s National Drug-Impaired Driving Initiative brings together experts, including law enforcement officials, prosecutors, substance abuse experts and others, to discuss strategies that can reduce drug-impaired driving.