Cannabis has been legal in Canada since October 2018, but driving while impaired by it, or with too much THC in your blood, is a criminal offence. If you have been stopped or charged with driving high in Ontario, you may be facing both a Criminal Code charge and separate provincial licence penalties. This guide explains how cannabis-impaired driving (often called a “cannabis DUI”) works in Ontario, what the penalties are and what you can do next.
How police test drivers for cannabis
Police in Ontario have several tools to investigate drug-impaired driving:
- Standardized Field Sobriety Tests (SFST) at the roadside, such as the walk-and-turn and one-leg-stand tests.
- Approved oral fluid drug screeners, which test a saliva sample for recent cannabis (THC) and cocaine use. A positive result does not prove impairment on its own, but it can lead to further testing.
- Drug Recognition Evaluation (DRE), a structured evaluation done at the police station by a specially trained officer.
- Blood samples, which are needed to prove the blood THC concentration offences.
You can be required to do roadside tests before you speak with a lawyer. Once you are arrested, or taken for a DRE or a blood demand, you have the right to call a lawyer without delay, and you should use it.
Criminal Code THC limits in Canada
The federal limits apply in every province and territory. Each offence is based on your blood THC level within two hours of driving:
- 2 ng to under 5 ng of THC per mL of blood: a less serious (summary) offence with a maximum fine of $1,000.
- 5 ng or more of THC per mL of blood: treated like alcohol-impaired driving, with a mandatory minimum $1,000 fine for a first offence, 30 days in jail for a second and 120 days for a third.
- 2.5 ng or more of THC combined with a blood alcohol level of 50 mg per 100 mL or more: also treated like alcohol-impaired driving, with the same mandatory minimums.
You can also be charged with impaired driving based on how you were driving and what the officer observed, even without a blood test. A conviction for the more serious offences also brings a mandatory driving prohibition, and any conviction leaves a criminal record.
Ontario roadside penalties for cannabis-impaired driving
In Ontario, the penalties for cannabis-impaired driving are the same as for alcohol-impaired driving. If you perform poorly on a Drug Recognition Expert (DRE) evaluation, a first occurrence brings:
- a 90-day immediate licence suspension
- a 7-day vehicle impoundment
- an 8-hour education course
- a $550 administrative penalty, plus a licence reinstatement fee
A second occurrence adds a 16-hour treatment program, and a third adds a six-month ignition interlock condition.
New and young drivers
Ontario’s zero-tolerance rules apply to cannabis. If you are 21 or under, or hold a G1, G2, M1 or M2 licence, you must have no alcohol and no drugs in your system when you drive. A first occurrence brings a 7-day suspension, an 8-hour course, a $250 penalty and a $60 to $1,000 fine if convicted. Commercial drivers (trucks and buses) face the same no-drugs rule, with a 3-day suspension for a first occurrence.
Medical cannabis and prescription drugs
A medical authorization for cannabis does not make it legal to drive while impaired or over the legal THC limits. The same goes for prescription and over-the-counter medications that affect your ability to drive. THC can stay in the body for some time, so regular medical users should get legal advice about their own situation.
What to do if you are charged with driving high in Ontario
- Write down what happened as soon as you can: the time you last used cannabis, where you were stopped, which tests you were given and what the officers said.
- Keep every document police gave you, including suspension notices and impound papers. Provincial review deadlines can be very short.
- Speak to an impaired driving lawyer before your first court date in the Ontario Court of Justice. Drug-impaired cases often turn on technical issues: whether the officer had grounds for a demand, how the DRE was done, how the blood sample was taken and timed, and whether your Charter rights were respected.
You can find an impaired driving lawyer in Ontario in our directory. Many offer an initial consultation.
Frequently asked questions
Yes. The Criminal Code makes it an offence to have 2 ng or more of THC per mL of blood within two hours of driving, whether or not you feel impaired. Police can also charge impairment based on your driving and their observations.
Yes. Police can use approved oral fluid (saliva) drug screeners and standardized field sobriety tests. A positive result can lead to a drug recognition evaluation at the police station or a demand for a blood sample.
No. A medical authorization lets you possess and use cannabis, but it does not permit you to drive impaired or over the legal THC limits. A lawyer can explain how your medical use may matter to the evidence in your case.
Refusing a lawful demand is a separate criminal offence, and it carries a mandatory minimum fine of $2,000 for a first offence. Provincial licence sanctions can also apply.
Sources
- Department of Justice Canada – Drug-impaired driving laws FAQ
- Government of Ontario – Impaired driving
- Department of Justice Canada – Impaired driving amendments Q&A
This article is general information about Ontario and federal law as of November 2026, not legal advice. Laws and penalties change; speak to a lawyer about your own situation.
