Cannabis Use and Motor Vehicle Accident Risk
"A review of over a dozen of these [laboratory] experiments reveals three findings. First, after using marijuana, people drive more slowly. In addition, they increase the distance between their cars and the car in front of them. Third, they are less likely to attempt to pass other vehicles on the road. All of these practices can decrease the chance of crashes and certainly limit the probability of injury or death if an accident does occur. These three habits may explain the slightly lower risk of accidents that appears in the epidemiological studies. These results contrast dramatically to those found for alcohol. Alcohol intoxication often increases speed and passing while decreasing following distance, and markedly raises the chance of crashes.(632)"
"Rulemaking petition to reclassify cannabis for medical use from a Schedule I controlled substance to a Schedule II, Exhibit B: Statement of Grounds," Prepared by Carter, Gregory T.; Earleywine, Mitchell; and McGill, Jason T. (Office of Lincoln D. Chafee, Governor Rhode Island and Office of Christine O. Gregoire, Governor of Washington, November 30, 2011), Filed With US Drug Enforcement Administration on November 30, 2011, p. 37.