> The evidence is very clear that a moderate or higher dose of cannabis impairs driver performance and several of the skills necessary for safe driving.
> ... largest degree of impairment is observed with tasks involving attention, tracking and psychomotor skills.
> These studies reveal that cannabinoids are the drugs most commonly found after alcohol in these individuals. Evidence from Canada is consistent with this observation; two recent studies detected cannabinoids in 13.9% and 19.5% of samples of seriously injured and fatally injured drivers, respectively.