This post is the simplest one we’ll ever write: don’t drive impaired. Cannabis-impaired driving is a criminal offence under federal law, with serious provincial consequences in Ontario on top of that. Here’s the practical breakdown of what that means.

The short version

In Canada, it’s illegal to operate a vehicle while impaired by cannabis. Period. The penalties under the Criminal Code can include fines, licence suspension, vehicle impoundment, and a criminal record — same as alcohol-impaired driving.

Ontario layers additional administrative penalties on top, including immediate roadside licence suspensions and fines that escalate by offence count.

What “impaired” means legally

Under federal law, there are specific THC blood-concentration limits that can trigger charges:

  • 2 ng of THC per ml of blood — summary conviction offence (lower penalty).
  • 5 ng of THC per ml of blood — hybrid offence (potentially indictable, higher penalty).
  • Any detectable THC combined with alcohol over 50 mg per 100 ml of blood — also a hybrid offence.

You don’t have to “feel” high to be over the limit. THC can stay measurable in your system long after the noticeable effects have worn off.

How testing works at the roadside

Police in Ontario can demand a roadside test if they have reasonable grounds to suspect impairment. Tools they can use:

  • Standardized Field Sobriety Tests — physical coordination tests.
  • Oral fluid screening devices — saliva swabs that detect recent cannabis use.
  • Drug Recognition Evaluations — a structured assessment by specially trained officers.

If you fail or refuse, you can be arrested. Refusing a demand for a sample is itself a criminal offence.

How long should you wait after use?

This is the question we get most, and the honest answer is longer than most people think — and longer than you feel “fine.”

Health Canada’s guidance is:

  • At least 6 hours after smoking or vaping before driving — and longer if the effects were strong.
  • At least 8 hours after consuming an edible, because edibles peak later and last longer.
  • Longer for higher doses, mixed substances, or new users.

These are minimums. Many people need significantly longer to be fully unimpaired. Tolerance doesn’t help here — frequent users can have detectable THC in their blood for days after their last use, even when they feel completely sober.

If you have any doubt, don’t drive. Take a cab, an Uber, or just wait it out.

Ontario’s zero-tolerance categories

Three groups of drivers face zero-tolerance rules in Ontario — any detectable THC at all is an offence:

  • Drivers aged 21 and under
  • Novice drivers — G1, G2, M1, M2
  • Commercial drivers — anyone operating a vehicle requiring an A-F licence or a CVOR

For these drivers, “I only had a little, hours ago” is not a defence. The standard is any detectable THC.

Passengers and open containers

It’s also illegal in Ontario to consume cannabis in a moving vehicle, full stop. This applies to passengers, not just the driver. Open cannabis in a vehicle has to be either:

  • in its original sealed packaging, or
  • out of reach of the driver and occupants — the trunk, typically.

A pre-roll in the centre console with a broken seal is enough to get the driver charged with an open-container offence.

If you’re consuming, plan ahead

Practical things that work:

  • Decide your ride home before you consume, not after.
  • If you live close enough, walk.
  • Keep transit and rideshare apps installed and signed in. Cannabis dulls planning ability; future-you will be grateful past-you set things up.
  • For cannabis-friendly social gatherings, designate a sober driver the same way you would for alcohol.

If you’re ordering from us in Stouffville, that’s part of the appeal — you don’t need to drive anywhere to begin with. Order delivery and stay put.

A reminder

Cannabis can affect reaction time, coordination, judgment, and attention for hours after the high feels gone. The legal limits exist because impaired driving kills people. The penalties exist because the consequences are severe. None of it is worth the alternative.

If you’ve consumed and you’re not sure if you’re okay to drive — you’re not.