DUI and Impaired Driving Defences in Ontario

The short answer

Impaired driving and over 80 charges can be defended. These cases are technical, and police must follow specific rules at every step, from the roadside demand to the breath test at the station. When police do not follow those rules, the evidence may be excluded.

No one can promise a result. However, every case deserves a close look at the evidence, especially the police video, because small details can make a large difference.

1. Was each demand lawful?

Every test depends on a lawful demand under s. 320.27:

• Roadside test with suspicion: Police need reasonable grounds to suspect alcohol in your body and that you drove in the last three hours.
• Mandatory alcohol screening: No suspicion is needed, but the stop must be lawful and the officer must have an approved screening device.
• Station tests: Police need reasonable grounds to believe you committed an impaired driving offence.

If a demand did not meet its legal test, the results can be challenged.

2. Your Charter rights

• Section 8: You are protected against unreasonable search and seizure, which includes breath and blood samples.
• Section 9: You are protected against arbitrary detention.
• Section 10(b): You have the right to be told you can speak to a lawyer, and a real chance to do so before station tests.

If police breached your rights, a judge can exclude the evidence under s. 24(2), which can mean the breath results cannot be used.

For example, if police did not give you a real chance to call the lawyer you asked for before the station tests, the breath results may be challenged.

3. Testing procedures

Breath results are treated as accurate only if the testing rules were followed. That includes the time between samples and the checks on the instrument. The defence can ask for the instrument records and the station video.

In drug cases, the drug recognition evaluation must be done and recorded properly.

4. Were you operating the vehicle?

The Crown must prove that you were operating the vehicle. Operating includes having care or control of it, even if you were not driving (s. 320.35).

If you were in the driver's seat, the law presumes you were operating the vehicle. You can rebut that presumption by showing you were not there to set the vehicle in motion, for example because you were sitting in a parked car for warmth while waiting for a ride.

Even then, the Crown may still prove care or control if there was a realistic risk that the car could be set in motion or cause danger. Courts look at where the keys were, whether the engine was running and why, and what your plan was to get home.

5. The two-hour window and drinking after driving

Over 80 is based on your blood alcohol level within two hours after driving. A narrow exception applies if you drank after you stopped driving and had no reason to expect a police test. See over 80 charges in Ontario.

6. Proof of impairment

For an impaired driving charge, as opposed to over 80, the Crown must prove that your ability to drive was impaired to some degree. Signs like red eyes or the smell of alcohol can have other causes, such as fatigue or allergies. Video often shows how you walked and spoke more fairly than written notes do.

7. Delay

You have a Charter right to be tried within a reasonable time under s. 11(b). Since 2026, Bill C-16 has required courts to consider remedies other than ending the case when this right is breached. Delay can still help a defence, but a stay is no longer the only possible result.

How a defence is built

1. Disclosure: Your lawyer obtains the officer's notes, the breath records and all available video.
2. Review: Your lawyer compares the video with the notes, step by step, and identifies any gaps.
3. Charter application: If there is a breach, your lawyer files a written application to exclude the evidence.
4. Hearing: The officers are questioned, and the judge decides whether to exclude the evidence.

Even when a full defence is not available, a well-prepared Charter argument can lead to a better resolution offer from the Crown.

What to do now

• Write down your timeline while you still remember it, including what you ate and drank.
• Note when you asked for a lawyer and what police said in response.
• Keep receipts, texts and the names of anyone who was with you.

Common police errors

Some of the most common problems in impaired driving cases involve delay in making the roadside demand, failing to tell a person about their right to a lawyer in clear terms, failing to give a real chance to reach the lawyer the person asked for, and errors in the timing of the breath samples. Other cases involve incomplete notes, missing video or instrument records that were not properly maintained. Each of these issues can affect whether the evidence is admitted at trial.

Possible outcomes

Effects beyond the sentence

A successful defence avoids a criminal record and the long list of consequences that come with it, including higher insurance costs, licence penalties and problems at the U.S. border. For a permanent resident, an impaired driving conviction can also lead to inadmissibility for serious criminality, because the maximum is 10 years.

How we can help

We can get the police video and breath records, review every demand and Charter step, and build the defence that fits your evidence. Call (647) 223-1980 for a free consultation.

Frequently asked questions