Quick answer: Driving while impaired by cannabis is a criminal offence in Canada, and Ontario adds its own roadside penalties: a drug-impaired driver faces an immediate 90-day licence suspension, a 7-day vehicle impoundment and a $550 penalty, before any court case. Drivers 21 and under, G1/G2/M1/M2 drivers and commercial drivers must have zero cannabis in their system. Canada’s Lower-Risk Cannabis Use Guidelines recommend waiting at least six hours after using cannabis before driving, and edibles can last much longer. The simplest rule: if you’ve used cannabis today, don’t drive.
Cannabis has been legal for adults 19+ in Ontario since 2018, but driving high has never been legal. Police in London, Middlesex County and across Ontario can test drivers at the roadside, and the penalties stack up quickly: provincial suspensions and fines on the spot, then possible criminal charges. This guide explains the rules, the THC limits, what happens if you’re stopped and how long to wait after using cannabis. It’s general information, not legal advice. For the wider rules on age, possession and where you can smoke, see our Ontario cannabis laws guide.
Is it illegal to drive high in Ontario?
Yes. Two sets of laws apply at once:
- Federal (Criminal Code): it’s a crime to drive while your ability is impaired by a drug, or to have THC in your blood above set limits within two hours of driving.
- Provincial (Ontario): the province applies its own immediate licence suspensions, vehicle impoundments, penalties and education programs, whether or not you’re later convicted.
Cannabis-impaired driving is treated the same way as alcohol-impaired driving in Ontario. It applies to cars, trucks, motorcycles, boats, snowmobiles and off-road vehicles.
THC blood limits in Canada
The Criminal Code sets these limits for THC (the compound in cannabis that causes the high; see what is THC), measured within two hours of driving:
| THC in blood | Type of offence | Penalty (per Justice Canada) |
|---|---|---|
| 2 ng to under 5 ng per ml | Summary (less serious) offence | Fine of up to $1,000 |
| 5 ng or more per ml | Hybrid offence | Same as alcohol-impaired driving: minimum $1,000 fine for a first offence, 30 days’ jail for a second, 120 days for a third |
| 2.5 ng or more per ml plus 50 mg alcohol per 100 ml blood | Hybrid offence (cannabis and alcohol combined) | Same as above |
You can also be charged with impaired driving at any THC level if police have evidence your ability to drive was impaired. And because THC clears the blood at different rates in different people (regular users often carry it longer), feeling fine is no guarantee you’re under the limit.
Ontario’s roadside penalties for drug-impaired driving
If you fail or refuse a drug test, or perform poorly in a Drug Recognition Expert (DRE) evaluation, Ontario applies these penalties right away:
| Occurrence | Licence suspension | Vehicle impound | Program | Penalty |
|---|---|---|---|---|
| 1st | 90 days | 7 days | 8-hour education course | $550 |
| 2nd | 90 days | 7 days | 16-hour treatment program | $550 |
| 3rd | 90 days | 7 days | 16-hour treatment program + 6-month ignition interlock | $550 |
A licence reinstatement fee applies to every suspension, and towing and storage costs for an impounded vehicle are on top. A lower “warn range” (failing the Standard Field Sobriety Test) brings a 7-, 14- or 30-day suspension with $250, $350 or $450 penalties.
If you’re convicted
- 1st conviction: licence suspension of at least 1 year, a mandatory program, and an ignition interlock for at least 1 year.
- 2nd within 10 years: at least 3 years’ suspension and at least 3 years of interlock.
- 3rd within 10 years: lifetime suspension (reducible after 10 years in some cases).
- 4th within 10 years: lifetime suspension with no reduction.
Courts can add fines and jail time, and a criminal record can affect jobs, travel to the U.S. and insurance rates for years.
Zero tolerance: young, novice and commercial drivers
| Who | Rule | Roadside penalties |
|---|---|---|
| Drivers 21 and under | No cannabis or alcohol in their system | 7/14/30-day suspension, $250/$350/$450, plus a fine of $60–$1,000 and possible extra suspension if convicted |
| G1, G2, M1, M2 licence holders (any age) | No cannabis or alcohol in their system | Same as above; a conviction can mean licence cancellation |
| Commercial drivers (A–F licences, CVOR vehicles, road-building machines) | No cannabis or alcohol in their system | 3-day suspension, $250/$350/$450 |
Zero tolerance means any detectable amount counts, even if you don’t feel high. If you’re 19 to 21 or still on a graduated licence, there’s no safe waiting period you can count on before driving.
How long should you wait to drive after using weed?
There’s no legal “safe” number of hours. Impairment depends on the dose, the THC potency, how you consumed it, your tolerance and whether you’ve mixed it with alcohol. What the official guidance says:
| Method | What to know | Guidance |
|---|---|---|
| Smoking or vaping | Effects start within minutes; research funded by CAA found higher crash-risk driving in young users even five hours after inhaling | Wait at least 6 hours (Lower-Risk Cannabis Use Guidelines), longer after a big session |
| Edibles and drinks | Effects can take 30 minutes to 2 hours to start, peak around 4 hours and last up to 12 hours (Health Canada) | Treat the whole day or night as no-driving; 6 hours is a minimum, not a target |
| Cannabis plus alcohol | Impairment is greater than either alone, and the combined THC limit is lower | Don’t drive |
Edibles are where people get caught out most. Because they kick in slowly, it’s easy to feel fine when you set off and then feel the full effect on the road. Our guide to how long edibles take to kick in explains the timing, and THC drinks vs alcohol covers why a “just one drink” mindset doesn’t carry over.
What happens at a roadside stop
- Reasonable suspicion. Police need a reasonable suspicion that you’ve used a drug (for example, the smell of cannabis, red eyes or admitting you’ve used it) before demanding a drug test.
- Oral fluid screening. An approved device tests a saliva sample. A positive result strongly suggests recent cannabis use.
- Standardized Field Sobriety Test. Trained officers can run physical coordination tests at the roadside.
- Drug Recognition Expert evaluation. At the station, a DRE can assess impairment and may demand a blood, urine or saliva sample.
Refusing a test carries the same roadside penalties as failing one, and refusal is a criminal offence in its own right.
Carrying cannabis in your car
- Keep it packed away. Cannabis must be in its original unopened packaging, or packed in baggage that isn’t readily available to anyone in the vehicle (the trunk is the simplest option).
- The fine: driving with cannabis readily available, or in open packaging, carries a $175 set fine under Ontario’s Cannabis Control Act.
- No consuming in the vehicle. That includes passengers. The only exception is a parked vehicle used as a residence, such as a camper.
Getting around London without driving
The easiest way to stay out of trouble is to plan your ride before you light up. In London, that means LTC buses, a taxi or rideshare, a designated driver, or simply staying in. Planning a night out? Our list of things to do in London, Ontario when high sticks to places you can walk, bus or ride to, and if you’re heading to a show, read our concert gummies guide first. And instead of driving to pick something up, you can get it delivered in London.
FAQ: weed and driving in Ontario
What is the penalty for driving high in Ontario?
At the roadside, a first drug-impaired driving occurrence brings a 90-day licence suspension, a 7-day vehicle impoundment, an 8-hour education course and a $550 penalty. A criminal conviction adds at least a 1-year suspension, an ignition interlock and possible fines or jail.
How long after smoking weed can I drive in Ontario?
There’s no guaranteed safe time. Canada’s Lower-Risk Cannabis Use Guidelines recommend waiting at least six hours after using cannabis, and longer after edibles or a large amount. If you’re 21 or under or on a G1/G2 licence, any THC in your system is an offence.
What is the legal THC limit for driving in Canada?
2 to under 5 nanograms of THC per millilitre of blood is a less serious offence; 5 ng or more, or 2.5 ng or more combined with a blood alcohol of 50 mg per 100 ml, is a more serious offence. Police can also charge you based on observed impairment at any level.
Can police test for weed at the roadside?
Yes. With reasonable suspicion, police can use an approved oral fluid (saliva) screening device, run a Standardized Field Sobriety Test, and require a Drug Recognition Expert evaluation and a blood sample.
Can I have weed in my car in Ontario?
Yes, if it’s in its original unopened packaging or packed in baggage that no one in the vehicle can easily reach. Having it readily available carries a $175 fine, and no one in the vehicle can consume it.
Sources
- Government of Ontario: About impaired driving
- Department of Justice Canada: Drug-impaired driving laws FAQ
- Health Canada: Lower-Risk Cannabis Use Guidelines FAQ
- CAA: How long should I wait to drive after consuming cannabis edibles?
- Ontario Court of Justice: Set fines, Cannabis Control Act (Schedule 0.3)
Penalties and limits are current as of November 2026 and can change. This article is general information, not legal advice.
Weekday orders (Monday to Friday) placed before noon (12:00 PM EST) are delivered the same day; see our London, Ontario delivery page for details. Cannabis is for adults 19+ in Ontario.
Buy weed online in Canada · Same-day weed delivery in London, Ontario on weekday orders placed before noon (12:00 PM EST).
