For years, countless ads and government officials have warned us of the dangers of driving drunk. That campaign has increased in recent years, asserting that “buzzed driving is drunk driving” and just as dangerous. But you don’t hear much from public officials about the risks of stoned driving.
Here in Colorado, legislators discuss what the proper limit should be for driving under the influence of THC. However, a number of studies suggest that this may not be as big a worry as it’s made out to be. As it turns out, driving while high is safer than driving drunk.
The most recent of these studies, released in late November of last year, shows that states with medical marijuana laws have lower rates of traffic fatalities. The study, conducted by Daniel Rees of the University of Colorado Denver and D. Mark Anderson of Montana State University, suggests that traffic deaths went down in states like Colorado due to a drop in alcohol consumption by young adults—which the researchers noticed also went down after states legalized medical marijuana.
Still, this study only implies a link between the laws and traffic deaths. Earlier studies (some of which were looked at by the aforementioned researchers) actually show that cannabis can make for more cautious drivers. Research from as early as 1988 suggests that people who drive after smoking pot take fewer risks on the road. Compare this to drunk drivers, who have known to underestimate their impairment behind the wheel.
Take, for instance, a study conducted in 1995 at the University of Adelaide in Australia. Subjects were road tested after a small dose of marijuana and at blood-alcohol levels of up to 0.08%—the legal limit in most of the United States. This study found that “[THC] users seem better able to compensate for its adverse effects while driving under the influence.”
Another road test, done by the US Department of Transportation in 1993, found that drivers under the influence of cannabis—though still impaired—were better off behind the wheel than those who took certain pharmaceuticals or alcohol. The report said, “Drivers under the influence of marijuana retain insight in their performance and will compensate when they can, for example, by slowing down or increasing effort. As a consequence, THC’s adverse effects on driving performance appear relatively small.”
Other experiments, including driving simulation studies and crash culpability research, have found similar results. An independent American study by G. Chesher and M. Longo (link to PDF of full study) in 2002 concluded that, although stoned drivers are “more likely than drug-free drivers to be culpable in road crashes,” their “culpability ratio” was close to that of sober drivers. Also in 2002, a study by the Canadian Senate Special Committee on Illegal Drugs found “drivers under the influence of cannabis [do not] represent a traffic safety risk.”
The evidence overwhelmingly suggests that driving while high is considerably safer than driving while drunk. Does this mean that any THC DUI argument is moot? Well, no. Many researchers concede that stoned drivers, while safer than drunk drivers, are still impaired. However, it is clear that more thought must go into this kind of legislation. Cannabis cannot be treated the same as alcohol when it comes to driving under the influence.