Impaired driving is one of the most commonly charged criminal offences in Canada, and the consequences of a conviction are severe — even for a first offence. A conviction means a criminal record, mandatory fines, a driving prohibition, an ignition interlock condition, and potentially significant impacts on employment and travel. If you have been charged with impaired driving in Ontario, understanding what you are facing and what defences may be available is essential. Early legal advice can make a decisive difference.

The Criminal Code Offences

Impaired driving offences in Canada are found in Part VIII.1 of the Criminal Code, primarily in sections 320.11 through 320.22. The most common charges are:

Operation While Impaired (s. 320.14(1)(a))

This is the "impaired" charge — operating a conveyance (motor vehicle, vessel, aircraft, or railway equipment) while your ability to operate it is impaired by alcohol, a drug, or a combination. The Crown does not need to prove a specific blood alcohol concentration; it must prove that your ability to drive was actually impaired. Evidence includes police observations such as slurred speech, unsteady gait, the smell of alcohol, erratic driving, and performance on standardized field sobriety tests.

Operation with a Blood Alcohol Concentration (BAC) Over 80 mg (s. 320.14(1)(b))

This charge — commonly called "over 80" — applies when your blood alcohol concentration is 80 mg of alcohol per 100 mL of blood or more at the time of driving or within two hours after. Proof comes from an Intoxilyzer breath test (an approved instrument) at the police station. The law creates an evidentiary presumption that the test result reflects the BAC at the time of driving, subject to certain exceptions.

Failure or Refusal to Comply (s. 320.15)

Refusing to provide a breath sample when lawfully demanded — at the roadside or at the station — is itself a criminal offence and carries the same mandatory penalties as an over-80 conviction. The demand can be made if an officer has reasonable grounds to suspect you have alcohol or drugs in your body (roadside screening device) or reasonable grounds to believe you have committed an impaired driving offence (approved instrument demand at the station).

The Two-Stage Testing Process

When police suspect impaired driving, the process typically involves two stages. First, at the roadside, an officer may demand that you provide a breath sample into an Approved Screening Device (ASD) — a handheld device that provides a "pass," "warn," or "fail" result. A "fail" — or a demand to accompany police based on reasonable grounds — then triggers a second demand at the station for samples into the Intoxilyzer 8000C (the approved instrument for evidentiary testing in Ontario). It is the Intoxilyzer results that are typically tendered as evidence of BAC.

Mandatory Minimum Penalties on Conviction

The Criminal Code sets mandatory minimum penalties for impaired driving offences. For a first offence:

For a second offence: a minimum 30-day jail sentence and a two-year driving prohibition. For a third or subsequent offence: a minimum 120-day jail sentence and a three-year driving prohibition. If the offence caused bodily harm or death, the penalties increase dramatically and may include lengthy prison sentences.

Ontario Licence Suspension and Ignition Interlock

In addition to criminal penalties, Ontario's Highway Traffic Act imposes immediate administrative licence suspensions at the roadside (90 days) and vehicle impoundment (7 days) when an over-80 or impaired charge is laid. Upon conviction, the province imposes a further suspension and requires participation in the Back on Track program and the ignition interlock program — a device installed in your vehicle that requires a clean breath sample before the car will start.

Available Defences

Impaired driving cases are among the most technical in criminal law. There are several categories of available defences:

Charter Defences (ss. 8, 9, and 10)

Police must follow strict constitutional rules when stopping, detaining, and demanding breath samples from drivers. If an officer made an arbitrary stop without reasonable suspicion, detained you longer than permitted, failed to provide timely access to counsel under s. 10(b), or failed to administer the ASD demand properly, your Charter rights may have been violated. Under s. 24(2) of the Charter, evidence obtained in breach of the Charter — including breath test results — may be excluded, which can result in a stay of proceedings or an acquittal.

Challenges to the Breath Test Results

The evidentiary presumption that the Intoxilyzer results reflect your BAC at the time of driving can be challenged. Evidence that you consumed alcohol shortly before driving (the "bolus drinking" or "last drink" defence), combined with expert evidence showing your BAC was actually below 80 mg% while driving, can defeat the over-80 charge. Calibration errors, improper observation periods, and instrument malfunctions are also potential grounds for challenge.

Identity and Care or Control

In some cases, the Crown may face difficulty proving that the accused was actually operating the vehicle, or that they had care or control in the relevant circumstances.

Impact on Employment and Travel

A criminal record for impaired driving affects far more than your ability to drive. Many employers — especially in regulated industries, security clearance environments, and professional licences — treat a criminal record as grounds for termination or disqualification. Entry into the United States may be refused, as a Canadian impaired driving conviction is treated as a DUI under American immigration law, making you potentially inadmissible without a US Entry Waiver.

At Silver Crest Law, we defend individuals charged with impaired driving in Ottawa and across Ontario. Contact us as soon as possible after an arrest — the earlier we are involved, the better positioned we are to identify and develop your defence.

This article provides general legal information about impaired driving charges in Ontario under the Criminal Code of Canada. It does not constitute legal advice. Every case is different. If you have been charged with an impaired driving offence, consult a criminal defence lawyer immediately.