While it might seem obvious, researchers Mark Asbridge, Jill A. Hayden and Jennifer L. Cartwright took the trouble to scientifically conclude that “acute cannabis consumption is associated with an increased risk of a motor vehicle crash, especially for fatal collisions.” They report their findings in the British Medical Journal – here’s the abstract:
Objective To determine whether the acute consumption of cannabis (cannabinoids) by drivers increases the risk of a motor vehicle collision.
Design Systematic review of observational studies, with meta-analysis.
Data sources We did electronic searches in 19 databases, unrestricted by year or language of publication. We also did manual searches of reference lists, conducted a search for unpublished studies, and reviewed the personal libraries of the research team.
Review methods We included observational epidemiology studies of motor vehicle collisions with an appropriate control group, and selected studies that measured recent cannabis use in drivers by toxicological analysis of whole blood or self report.