Photo: Ken Lund, CC BY-SA 2.0, via Wikimedia Commons
A medical cannabis authorization does not let you drive impaired anywhere in Canada. The federal Criminal Code THC limits apply to every driver. On top of that, most provinces set zero tolerance for drugs for new drivers. Ontario is the one province confirmed here to exempt medical cannabis users from its zero-tolerance drug rule, and even there you can still be charged if your driving is impaired. Everywhere else, assume zero means zero until your licensing office tells you otherwise.
This page covers the law, not treatment. Talk to the doctor who authorized your cannabis about how it affects you.
Federal THC limits for all drivers
| Blood level | Offence | Penalty (first offence) |
|---|---|---|
| 2 ng to under 5 ng of THC per ml | Less serious offence (summary conviction) | Maximum $1,000 fine |
| 5 ng or more of THC per ml | Drug-impaired driving | Mandatory minimum $1,000 fine, up to 10 years’ imprisonment |
| 50 mg of alcohol per 100 ml of blood and 2.5 ng or more of THC per ml | Combined alcohol and cannabis offence | Mandatory minimum $1,000 fine, up to 10 years’ imprisonment |
A second offence carries at least 30 days in jail and a third at least 120 days. Refusing a demand for a sample carries a minimum $2,000 fine for a first offence. The Department of Justice page sets out these limits with no exception for medical users.
Zero tolerance for new drivers
Provinces add their own rules for learners and novices. The list of which provinces set zero drugs for new drivers is in Impaired driving in Canada for new drivers. In short, Ontario, British Columbia, Alberta, Manitoba, PEI, New Brunswick and Yukon set zero drugs for new drivers, and Saskatchewan sets zero drugs for everyone.
Does a medical authorization exempt a novice driver?
Ontario: yes from zero tolerance, no from impairment
Ontario’s zero-tolerance drug rule covers drivers who are 21 or under, anyone with a G1, G2, M1 or M2 licence, and commercial drivers. They cannot have any cannabis in their system as detected by a federally approved screening device. Ontario states that if you have a valid medical cannabis prescription you “will not be subject to the zero tolerance drug requirements”, but you can still face penalties and criminal charges if your ability to drive is impaired.
Other provinces
Check with your provincial licensing office whether any medical exemption from novice zero-tolerance rules applies. Before you drive as a learner while using medical cannabis, ask your provincial licensing office (ICBC or RoadSafetyBC, Alberta Transportation, the SAAQ and so on) in writing how its rule applies to you.
What the medical standard says about cannabis
RoadSafetyBC’s chapter on drugs and driving, which follows the national standard, says:
- Medical cannabis users should be advised not to drive for at least five hours, and preferably at least 24 hours, after use.
- People who use more than about 1.5 grams (3 joints) a day should be counselled not to drive during those periods.
- Someone newly prescribed medical cannabis should not drive until the effect on them is known.
Prescription and over-the-counter medicines
- Using a psychotropic medicine does not automatically make you ineligible for a licence. The test is whether your driving abilities are impaired.
- The standard states plainly that a driver cannot compensate for the effects of psychotropic drugs.
- Sedatives and sleeping pills impair more at higher doses and when the drug lasts longer in the body.
- Read the label and ask your pharmacist whether a medicine affects driving. Combining any of these with alcohol or cannabis is riskier still.
Practical points for learners
- Never drive, even supervised, if you feel any effect.
- Do not consume cannabis in a vehicle that is being driven or will be driven. Ontario bans this outright.
- If your condition itself affects driving, see the condition guides in the Canada medical conditions hub, such as ADHD, anxiety and mental health or epilepsy.
Sources
- Department of Justice Canada, “Impaired Driving Laws” (justice.gc.ca)
- Government of Ontario, “Cannabis and driving” (ontario.ca)
- Government of Ontario, “Cannabis laws” (ontario.ca)
- Government of British Columbia, “Chapter 15: Drugs, alcohol and driving”, RoadSafetyBC medical standards (gov.bc.ca)