Grant: Operating Grant

Marijuana is the most commonly used illicit drug in Canada and many drivers, especially young adults, report driving after using marijuana. Although there is abundant experimental evidence that marijuana, either alone or in combination with alcohol, impairs the skills required for safe driving, real world data on the contribution of marijuana to car crashes is mixed. This uncertainty hinders the ability of traffic safety policy makers to develop effective, evidence based, traffic laws or road safety campaigns targeting people who drive while impaired by marijuana. The primary objective of the study proposed here is to determine whether injured drivers who used marijuana before a car crash are more likely to have caused the crash than those who did not. Our aim is to improve traffic safety by providing current North American data that can be used to inform the development of evidence based road safety policy targeting people who drive while impaired by marijuana.