It is illegal to drive impaired, regardless of the source of impairment. 1
The federal government has passed new legislation, the Impaired Driving Act, which introduces three new offences for driving under the influence of drugs and establishes legal limits for blood delta-9-tetrahydrocannabinol (THC) limits. Individuals are prohibited from driving within two hours of being over the legal limits. 2
|Offence||Blood THC Level||Federal Penalty|
|1. Driving under the influence of cannabis||2ng* or more but less than 5ng of THC per 1ml* of blood||Maximum $1,000 fine|
|2. Driving under the influence of cannabis||5ng or more of THC per 1ml of blood||Mandatory minimum $1,000 fine – 120 days imprisonment|
|3. Driving under the influence of cannabis combined with alcohol||50mg* of alcohol per 100 ml blood and 2.5ng or more of THC per 1ml of blood|
*ng = nanogram, *ml = millilitre, *mg = milligram
3 Ramaekers JG, Berghaus G, van Laar M, Drummer OH. Dose related risk of motor vehicle crashes after cannabis use. Drug and Alcohol Dependence. 2004;73:109-119.
4 Hartman RL, Huestis MA. Cannabis effects on driving skills. Clin Chem. 2013;59:478-92.Broyd SJ,. Van Hell HH, Beale C, Solowij N. Acute and chronic effects of cannabinoids on human cognition—a systematic review. Biol Psychiatry. 2016; 79(7):557–567.
5 Karschner EL, Swortwood MJ, Hirvonen J, Goodwin RS, Bosker WM, Ramaekers JG et al. Extended plasma cannabinoid excretion in chronic frequent cannabis smokers during sustained abstinence and correlation with psychomotor performance. Drug Testing and Analysis.2016; 8(7): 682–9.
6 Rogeberg O, Elvic R. The effects of cannabis intoxication on motor vehicle collision revisited and re-vised. Addiction. 2016;111(8):134-1359.
7 Asbridge M, Mann R, Cusimano MD, Trayling C, Roerecke M, Tallon JM, et al. Cannabis and traffic collision risk: findings from a case-crossover study of injured drivers presenting to emergency departments. Int Public Health. 2014; 59(2):395-404. Neavyn MJ, Blohm E, Babu KM. Medical Marijuana and Driving: A Review. Medical Toxicology. 2014;10:269-279.
9 Els C, Jackson TD, Tsuyuki RT et al. Impact of cannabis use on road traffic collisions and safety at work: systematic review and meta-analysis. Canadian Journal of Addiction. 2019; 10(1): 8-15.
10 Downey LA, King R, Papafotiou K, Ogden E, Boorman M, Stough C. The effects of cannabis and alcohol on simulated driving: Influences of dose and experience. Accid Anal Prev. 2013; 50: 879-886.
12 Canadian Pharmacists Association. Cannabis Monograph. Toronto, ON: Canadian Pharmacists Association; 2018.
13 Health Canada. Information For Health Care Professionals: Cannabis (marihuana, marijuana, and the cannabinoids). Ottawa, ON: Health Canada; 2013 [cited Oct 3 2019]
14 Arkell TR, Lintzeris N, Kevin RC et al. Cannabidiol (CBD) content in vaporized cannabis does not prevent tetrahydrocannabinol (THC)-induced impairment of driving and cognition. Psychopharmacology. 2019; 326: 2713.
16 Canadian Medical Association. Determining Medical Fitness to Operate Motor Vehicles: CMA Driver’s Guide, 9th Ed. Ottawa, ON: Canadian Medical Association; 2017 [cited Sep 17 2018].
19 Leirer VO, Yesavage JA, Morow DG. Marijuana carry-over effects on aircraft pilot performance. Aviat. Space Environ. Med. 1991; 62: 221–227.
20 College of Family Physicians of Canada. Authorizing Dried Cannabis for Chronic Pain or Anxiety: Preliminary Guidance from the College of Family Physicians of Canada. Mississauga, ON: College of Family Physicians of Canada; 2014 cited Sep 19 2018.
21 Kahan M, Srivastava A, Spithoff S, Bromley L. Prescribing smoked cannabis for chronic noncancer pain. Canadian Family Physician. 2014;60:1083-1090.
22 Fischer B, Russell C, Sabioni P, van den Brink W, Le Foll B, Hall W, et al. Lower-Risk Cannabis Use Guidelines: A Comprehensive Update of Evidence and Recommendations. Public Health Policy. 2017;107(8):e1-e12.
Updated: October 15, 2019