If I may just add on the same topic of drug-affected driving, a recent report issued by the International Narcotics Control Board, in 2013, cites that cannabis is the most prevalent illicit drug detected in drivers in Canada, the United States, and Europe. The same report also cites that habitual cannabis use actually links to a 9.5-fold increase in driving accidents.
Even international reports are also obviously citing the cognitive impairments and the significant increase in the risk of death due to vehicle accidents with cannabis use.