Aspect: Drug Driving

Cannabis impairment is generally weak and probably normally below a threshold where driving performance is dangerously degraded.

Results indicate blood and oral fluid THC concentrations are relatively poor or inconsistent indicators of cannabis-induced impairment. This contrasts with the much stronger relationship between blood alcohol concentrations and driving impairment.

Use of illicit drugs is not the cause of major road trauma. The major substance cause of death or injury is, in order; alcohol, and prescription drugs. Presence of THC in the mouth does not necessarily make you or your driving more dangerous.

Cannabis produces little or no car-handling impairment in driving studies. This is consistently less than moderate doses of alcohol and many legal medications.