I said I wasn't sure. Personally I believe driving impaired is wrong but it appears cannabis may not be "as bad" as alcohol, but you are still impaired. I think it would be very hard to make the argument that impaired drivers are "safer" than sober drivers. From the study "
THE EFFECT OF CANNABIS COMPARED WITH ALCOHOL ON DRIVING"
"In summary, laboratory tests and driving studies show that cannabis may acutely impair several driving-related skills in a dose-related fashion, but that the effects between individuals vary more than they do with alcohol because of tolerance, differences in smoking technique, and different absorptions of THC. Driving and simulator studies show that detrimental effects vary in a dose-related fashion, and are more pronounced with highly automatic driving functions, but more complex tasks that require conscious control are less affected, which is the opposite pattern from that seen with alcohol. Because of both this and an increased awareness that they are impaired, marijuana smokers tend to compensate effectively for their impairment by utilizing a variety of behavioral strategies such as driving more slowly, passing less, and leaving more space between themselves and cars in front of them. Combining marijuana with alcohol eliminates the ability to use such strategies effectively, however, and results in impairment even at doses that would be insignificant were they of either drug alone. Case-control studies are inconsistent, but suggest that while low concentrations of THC do not increase the rate of accidents, and may even decrease them, serum concentrations of THC higher than 5 ng/mL are associated with an increased risk of accidents (
Figure 2). Overall, though, case-control and culpability studies have been inconclusive, a determination reached by several other recent reviewers.
101,
102 Similar disagreement has never existed in the literature on alcohol use and crash risk."