Cruising on Cannabis

Cruising on Cannabis: Putting the Breaks on Doped Driving Misconceptions

By Paul Armentano

Cannabis and Driving

Policy debates regarding marijuana-law reform, including those involving the legalization of medicinal cannabis, invariably beg the question: "What about marijuana and driving?" The concern is a valid one. In fact, NORML's own "Principles of Responsible Cannabis Use" invoke a "no driving" clause, stating: "Although cannabis is said by most experts to be safer than alcohol and many prescription drugs with motorists, responsible cannabis consumers never operate motor vehicles in an impaired condition."

Nevertheless, concerns regarding doped driving should not be an impediment to marijuana-law reform. Alcohol is legal in America, yet every state maintains tough laws punishing those who choose to drive impaired by it. There is no reason why similar principles should not regulate cannabis consumption.

Moreover, emerging scientific research indicates that cannabis actually has far less impact on the psychomotor skills needed for driving than alcohol does, and is seldom a causal factor in automobile accidents. A pair of international studies released in the spring of 2001 bolsters this argument.

The first, conducted by Britain's Transport Research Laboratory, found that volunteers performed better on a driving simulator under the influence of pot than they did after consuming alcohol. According to the study, marijuana only adversely impacted subjects' ability to maintain a constant speed and control while driving around a figure-eight loop. Reaction time and all other measures of driving performance remained unaffected. Researchers also noted that the subjects who had smoked marijuana - unlike alcohol users - were aware of their impairment and attempted to compensate for it by driving more cautiously.

Similar results were also reported in March by a South Australian team at the Department of Clinical and Experimental Pharmacology at the University of Adelaide. Their epidemiological review of automobile accidents found that alcohol "overwhelmingly plays the greatest role in road crashes ... [and] conversely, ... marijuana has a negligible impact on culpability." The study was a follow up to a 1998 analysis of 2,500 injured drivers that previously determined cannabis to have "no significant effect" on drivers' culpability in motor vehicle accidents.

In fact, most marijuana and driving experiments give pot a relatively clean bill of health, particularly when compared to alcohol. A review of two-decades worth of driving simulator and on-road studies by Alison Smiley for Toronto's Centre for Addiction and Mental Health concluded that although marijuana temporarily impairs driving behavior, "this impairment is mitigated in that subjects under marijuana treatment appear to perceive that they are indeed impaired [and] where they can compensate, they do."

With respect to comparisons between the effects of alcohol versus marijuana, the author asserted, "In contrast to the compensatory behavior exhibited by subjects under marijuana treatment, subjects who have received alcohol tend to drive in a more risky manner." Smiley's assessment concludes, "The more cautious behavior of subjects who have received marijuana decreases the impact of the drug on performance, whereas the opposite holds true for alcohol."

Transportation data says likewise. A 1997 examination of motor vehicle injuries by the University of Michigan Transportation Research Institute concluded that alcohol is "the major drug associated with injury," and found no evidence to support the accusation that illicit drugs are a major factor in auto crashes. An earlier analysis published by the U.S. National Highway Transportation Safety Administration of 1,882 drivers killed in motor vehicle accidents also determined that alcohol, not pot, was the "dominant problem" in drug-related traffic accidents.

That said, are we to believe that it's ever safe to get high and drive? Not at all. However, what is apparent is that marijuana's slight impairment on psychomotor skills generally falls within the range of safety Americans accept for prescription medications and other legal, potentially debilitating factors such as fatigue or cell phones. As such, the question of marijuana and driving should remain a public policy concern for drug law reformers, but not a serious political obstacle to marijuana-law reform.