What “Impaired Driving” Actually Means
Under the Criminal Code of Canada, the offence commonly called “impaired driving” or “DUI” is found at section 320.14(1)(a). It makes it an offence to operate a conveyance — or have care or control of one — while your ability to operate it is impaired to any degree by alcohol, a drug, or a combination of both.
The phrase “to any degree” is critical. The Crown does not need to prove you were falling-down drunk. Even a slight departure from your normal ability to drive can satisfy the legal test. This is a lower bar than many people realize.
The Criminal Code does not use the term “DUI.” That is American shorthand that has become common in Canada. The formal Canadian charges are impaired operation and operation over 80 mg (often called “over 80”). They are distinct offences, charged separately, with different elements the Crown must prove.
Impaired Driving vs. Over 80: Two Different Charges
Most people arrested for drunk driving are charged with both impaired operation and over 80. They sound similar but work differently. For a full breakdown of both charge types, penalties, and aggravating factors, see our guide to DUI charges in Ontario.
| Impaired Operation — s. 320.14(1)(a) | Over 80 — s. 320.14(1)(b) | |
|---|---|---|
| What Crown proves | Ability to drive was impaired | BAC was at or above 80 mg/100 mL |
| Key evidence | Officer observations, driving pattern, coordination tests | Breathalyzer readings from approved instrument |
| Primary defence | Challenge observations — alternative explanations | Challenge breathalyzer accuracy or admissibility |
| Penalties | Identical | Identical |
The penalties are the same for both charges: a mandatory minimum $1,000 fine and one-year driving prohibition for a first offence, 30 days imprisonment and a two-year prohibition for a second, and 120 days imprisonment and a three-year prohibition for a third or subsequent offence. But the defences are fundamentally different, because the evidence the Crown relies on is different.
What the Crown Must Prove
For an impaired driving charge under section 320.14(1)(a), the Crown must prove three things beyond a reasonable doubt:
- You operated a conveyance (or had care or control of one). “Operate” means more than just driving — it includes having care or control of a parked vehicle if you had the ability to set it in motion.
- Your ability to operate it was impaired. This is based on the officer’s observations: driving pattern, physical appearance (bloodshot eyes, flushed face, smell of alcohol), speech (slurred, confused), coordination (unsteady on feet, fumbling with documents), and performance on field sobriety tests.
- The impairment was caused by alcohol, a drug, or both. The Crown must connect the observed impairment to a substance, not to fatigue, illness, injury, or some other cause.
If the Crown cannot prove any one of these elements, the charge fails. This is where defence strategy begins.
How Impaired Driving Charges Are Fought
There is overwhelming pressure to plead guilty to impaired driving charges — particularly for a first DUI charge. Crowns and even some defence lawyers present it as a straightforward process — plead guilty, pay the fine, move on. But a guilty plea means a criminal record, a licence suspension, an interlock device, insurance increases, and a US travel ban. The consequences last years. The defences are worth exploring.
Challenging the Observations of Impairment
The Crown’s case on impaired driving depends heavily on the arresting officer’s subjective observations. These can be challenged: bloodshot eyes may result from fatigue, allergies, or crying. An unsteady gait may reflect a medical condition, footwear, or an uneven road surface. Fumbling with documents is normal when nervous. Slurred speech can result from a speech impediment, dental work, or anxiety.
Cross-examination of the arresting officer is often the most important part of an impaired driving trial. Inconsistencies between the officer’s notes, their testimony, and any video evidence can create reasonable doubt.
Challenging the Traffic Stop
The police must have a lawful basis to stop your vehicle. While RIDE checkpoints and random traffic stops are generally permissible under the Highway Traffic Act, a stop motivated by racial profiling or conducted without any legitimate purpose violates section 9 of the Charter (arbitrary detention). If the stop was unlawful, all evidence obtained as a result may be excluded under section 24(2) of the Charter.
Right to Counsel Violations
Upon arrest, you have the right under section 10(b) of the Charter to be informed of your right to retain and instruct counsel without delay. If police failed to inform you of this right, delayed your access to a lawyer, or continued the investigation before you had spoken to counsel, any evidence obtained may be excluded. Right to counsel violations are among the most common and effective grounds for exclusion of evidence in impaired driving cases.
Challenging the Breathalyzer
For an over 80 charge, the breathalyzer results are the Crown’s entire case. Defences include challenging the maintenance and calibration records of the approved instrument, whether the mandatory observation period before testing was followed, whether the qualified technician operated the instrument correctly, and whether physiological factors like mouth alcohol or gastric reflux affected the readings. Refusing a breath sample is itself a criminal offence — see our guide on refusing a breathalyzer in Ontario.
Mandatory Alcohol Screening: Expanded Police Powers
Since Bill C-46 took effect in December 2018, police have the power to demand a breath sample from any driver they lawfully stop — even without reasonable suspicion that the driver has been drinking. This is called mandatory alcohol screening under section 320.27(2) of the Criminal Code.
At a RIDE checkpoint or routine traffic stop, the officer can require you to blow into an approved screening device immediately. There is no threshold requirement — the officer does not need to smell alcohol, observe slurred speech, or see a driving pattern that suggests impairment. A “fail” result on the screening device provides the officer with grounds to arrest you and demand two formal breath samples at the police station.
Mandatory alcohol screening has significantly expanded police enforcement capabilities. However, the stop itself must still be lawful — an officer cannot pull you over for no reason at all — and the screening device must be an approved instrument that has been properly maintained. Challenges to the lawfulness of the stop and the reliability of the screening device remain viable defence strategies under sections 8 and 9 of the Charter.
Conviction vs. Resolution: What Is at Stake
The consequences of an impaired driving charge depend entirely on how the case ends. The following table compares the three most common outcomes.
| Consequence | Criminal Conviction | Careless Driving | Acquittal / Withdrawal |
|---|---|---|---|
| Criminal record | Yes | No | No |
| Driving prohibition | 1 year minimum | Up to 2 years (often none) | None |
| Ignition interlock | Required | Not required | Not required |
| US travel | Inadmissible | No effect | No effect |
| Insurance impact | Severe ($5k–$10k/year) | Moderate increase | None |
| Fine | $1,000 minimum | $400–$2,000 | None |
The Process: Step by Step
Arrest and Release
After being charged, you will typically be released from the station on an undertaking with conditions — a promise to appear in court, a condition not to drive, and sometimes a condition not to consume alcohol. Your licence will be subject to an immediate 90-day administrative suspension imposed by the Ministry of Transportation.
First Court Appearance
Your first court appearance is procedural. You will not enter a plea. The matter will be adjourned to allow the Crown to provide disclosure — the evidence against you. Expect this process to take 8 to 14 months from charge to trial in the GTA.
Disclosure Review and Defence Strategy
Your lawyer will review the disclosure package: officer’s notes, breathalyzer certificates, video recordings, radio logs, and any other evidence. This is where defences are identified. Charter violations, procedural errors, and gaps in the Crown’s evidence are found in the disclosure, not in the courtroom.
Resolution or Trial
Based on the disclosure, your lawyer may negotiate with the Crown for a resolution — potentially a withdrawal of the charge, a peace bond, or a plea to a lesser offence such as careless driving under the Highway Traffic Act (which avoids a criminal record). If a satisfactory resolution is not available, the matter proceeds to trial.
Drug-Impaired Driving
Since the legalization of cannabis in October 2018, drug-impaired driving has received increased enforcement attention. The impaired driving offence under section 320.14(1)(a) applies to impairment by any substance — cannabis, prescription medications, cocaine, opioids, and others.
The Criminal Code also creates per se drug offences with prohibited blood drug concentrations: for THC (cannabis), having 2 but less than 5 nanograms per mL of blood is a summary offence, while 5 nanograms or more triggers the same penalties as impaired driving. Having both THC (at or above 2.5 ng) and alcohol (at or above 50 mg per 100 mL) is also a criminal offence.
Drug impairment is harder for the Crown to prove than alcohol impairment because there is no roadside screening device equivalent to the approved screening device for alcohol. Police rely on Drug Recognition Evaluators (DREs) — officers with specialized training who conduct a 12-step evaluation to determine impairment and the category of drug involved. The DRE protocol is vulnerable to challenge on multiple grounds, including the officer’s qualifications, the conditions under which the evaluation was conducted, and whether the evaluation followed the required steps.
What Comes After a Conviction
The consequences of an impaired driving conviction extend far beyond the criminal sentence. A first offence conviction means a $1,000 fine, a one-year driving prohibition, mandatory completion of Ontario’s Back on Track program, an ignition interlock device for at least one year, dramatically increased insurance premiums (often $5,000 to $10,000 per year), a permanent criminal record, and inadmissibility to the United States. These consequences last years and affect employment, professional licensing, and daily life. For a detailed breakdown of all penalties, see our guide to DUI penalties in Ontario.
Evidence Exclusion Under the Charter
The Canadian Charter of Rights and Freedoms protects individuals from unlawful searches, arbitrary detention, and denial of the right to counsel. When police violate these rights during an impaired driving investigation, the evidence obtained may be excluded under section 24(2) of the Charter.
The test for exclusion comes from the Supreme Court of Canada’s decision in R v. Grant, which requires the court to balance three factors: the seriousness of the Charter-infringing conduct, the impact of the breach on the accused’s Charter-protected interests, and society’s interest in an adjudication on the merits. In impaired driving cases, the most commonly excluded evidence is breathalyzer results obtained after a right to counsel violation or an unlawful demand.
If the breathalyzer results are excluded, the Crown often cannot proceed with the over 80 charge at all — the readings were the entire case. This may lead to a withdrawal, a stay of proceedings, or a resolution to a lesser offence. Even on the impaired driving charge, the exclusion of key evidence can fatally weaken the Crown’s case.
Why Fighting the Charge Matters
Impaired driving charges have viable defences more often than people expect. The police must follow a precise sequence of procedures from the traffic stop through the breath test, and errors at any point can result in evidence being excluded or charges being withdrawn.
RH Criminal Defence has challenged breath test results, argued Charter violations at the roadside, and defended impaired driving charges at courthouses across Ontario. If you have been charged, the disclosure needs to be reviewed by a criminal defence lawyer before any decisions about your case are made.