Brubacher JR, et al. - Via performing a responsibility analysis, researchers examined the contribution to the crash by drivers injured in motor vehicle collisions who test positive for Δ-9-tetrahydrocannabinol or other drugs vs those who test negative. In British Columbia, Canada, they conducted a prospective case-control study of non-fatally injured motor vehicle drivers who required blood tests for clinical purposes following a motor vehicle collision. Evidence revealed no increased crash risk in drivers with Δ-9-tetrahydrocannabinol < 5 ng/ml and a statistically non-significant heightened risk of crash responsibility (odds ratio = 1.74) in drivers with Δ-9-tetrahydrocannabinol ≥ 5 ng/ml.