Reducing cannabis-impaired driving: is there sufficient evidence for drug testing of drivers?

There is research evidence that marijuana use to the point of intoxication on the part of automobile drivers results in increased risk of motor vehicle crashes. Cannabis use produces dose-related cognitive and behavioral impairments in laboratory and simulation studies. The authors review the research literature on this topic, noting that cannabis users in surveys are more likely to report being involved in accidents than drivers who do not use the drug, and cannabis is the illicit drug detected most often in drivers who have been killed in motor vehicle crashes. Recent studies have provided more evidence that cannabis-affected drivers are at a higher risk of being involved in crashes, by approximately two to three times. This is, however, a much lower risk than alcohol use in automobile drivers, which increases risk of involvement in a crash six to fifteen times more than sober drivers.