Reviewed by the DUI Lawyer Toronto defence teamUpdated
A DUI charge is an allegation, not a conviction. The Crown must prove every element beyond a reasonable doubt, and police must follow strict rules at each stage of an impaired driving investigation. This guide explains how DUI charges are defended in Toronto, from the roadside test to the first court date, so you can see where the evidence may be open to challenge.
The right defence always depends on the facts, and no approach works in every case. What follows is general information, not legal advice about your situation.
How does roadside testing work in Ontario?
Most impaired driving investigations begin at the roadside. Police may stop a driver at a RIDE checkpoint, for a traffic violation or after a collision. Once you are lawfully stopped, an officer with an approved screening device can demand a breath sample, even without any suspicion that you have been drinking. This is known as mandatory alcohol screening.
A roadside result is mainly a screening tool. It helps the officer decide whether there are grounds for a formal breath test. A fail on the screening device usually leads to an arrest and a demand for breath samples into an approved instrument at the station.
Police can also investigate drug impairment at the roadside, including by demanding an oral fluid sample, and may demand a drug recognition evaluation at the station. Drug-impaired driving charges often turn on how those steps were carried out.
A defence review of the roadside stage asks questions such as:
- Was the stop itself lawful, and was the driver lawfully stopped before the demand was made?
- Did the officer have an approved screening device when the demand was made?
- Was the demand made promptly and in proper form?
- In a refusal case, did the driver truly refuse, or did they try and fail to provide a suitable sample?
That last question is central to many breath test refusal cases. If you want to know what to expect at a check stop, see our article on what happens at a RIDE checkpoint.
How can breathalyzer evidence be challenged?
In an over 80 prosecution, the Crown relies on breath samples taken at the station with an approved instrument. In Ontario, that instrument is the Intoxilyzer 8000C. The readings can look conclusive, but they are only as reliable as the machine, the operator and the process behind them.
Disclosure is where a breath defence begins. It should include the instrument's records and maintenance logs, the breath technician's notes and the station video. We review that material for issues such as:
- Maintenance and calibration. Gaps or irregularities in the instrument's service and test records.
- Operator procedure. Whether the qualified technician followed the required steps and recorded them accurately.
- Timing. When the samples were taken compared with when driving ended, since the offence concerns your blood alcohol concentration within two hours of operating.
- Observation period. Whether the technician watched you before testing to rule out mouth alcohol from burping or regurgitation.
- Medical and physical factors. Conditions such as acid reflux that may affect a result.
Readings close to a threshold deserve extra attention. A blood alcohol concentration of 120 mg or more is an aggravating factor at sentencing, and higher readings raise the minimum fine for a first offence. Our article on how long a breathalyzer can detect alcohol explains more about how alcohol moves through the body.
What Charter rights apply during a DUI investigation?
The Canadian Charter of Rights and Freedoms limits what police can do during an impaired driving investigation. The rights that come up most often are:
- Section 8: protection against unreasonable search or seizure. Taking breath or blood samples is a seizure, so the demand must be lawful.
- Section 9: protection against arbitrary detention. A detention must have a lawful basis.
- Section 10(b): the right to retain and instruct counsel without delay, and to be told about that right. After an arrest, police must give you a reasonable opportunity to contact a lawyer, and delays or refusals can become a Charter issue.
When a right is breached, the defence can apply to exclude the evidence under section 24(2). The court decides whether admitting the evidence would bring the administration of justice into disrepute, using the framework set by the Supreme Court of Canada in R. v. Grant. If key evidence such as the breath results is excluded, the Crown may not be able to prove the charge.
Delay can also matter. You have the right to be tried within a reasonable time, and in R. v. Jordan the Supreme Court set a presumptive ceiling of 18 months for cases in the Ontario Court of Justice. Unreasonable delay beyond that ceiling can lead to a stay of the charges.
What happens after a DUI arrest?
After the breath tests, most drivers are released with paperwork setting a first court date. Several things then happen at once, on separate tracks.
Provincial consequences start immediately. If you blew over 80, refused or were found impaired after a drug evaluation, Ontario imposes a 90-day Administrative Driver's Licence Suspension, a 7-day vehicle impoundment and an administrative monetary penalty. These apply even though you have not been convicted. Our article on the 90-day ADLS suspension explains how it works.
The criminal case begins. At your first appearance in the Ontario Court of Justice, the Crown provides initial disclosure. Your lawyer reviews it, requests anything missing, such as video or instrument records, and assesses the strength of the case.
Some decisions are time-sensitive. Ontario's reduced suspension program, for example, can let eligible first offenders who resolve their case early drive sooner with an ignition interlock, but the eligibility rules and deadlines are strict. Getting advice early keeps your options open, whether you plan to contest the charge or resolve it.
The case resolves. A charge may be withdrawn, resolved through a negotiated outcome or decided at trial. You make the final decision after hearing a clear recommendation. If there is a conviction, the penalties described on our DUI fines and penalties page apply.
For a checklist of first steps, read what to do if you are charged with a DUI, or find your offence on our overview of DUI charges. To see how these defences have played out in practice, review our DUI case results.
Frequently asked questions
Do I have to provide a roadside breath sample in Ontario?
Generally, yes. Under mandatory alcohol screening, an officer who has an approved screening device can demand a roadside breath sample from any driver who is lawfully stopped, even without suspicion of drinking. Failing or refusing to comply without a reasonable excuse is a criminal offence with the same kind of penalties as blowing over 80, including a minimum fine of $2,000 on a first offence.
Can I speak to a lawyer before the roadside breath test?
Usually not. A roadside screening demand must be complied with right away, and you generally cannot delay it to call a lawyer. The right to counsel without delay applies once you are arrested and taken for formal breath testing at the station. At that point, police must tell you about the right and give you a reasonable opportunity to speak with a lawyer.
Can breathalyzer results be thrown out?
Sometimes. Breath results can be challenged if the instrument was not properly maintained, the technician did not follow the required procedure, or the samples were taken in a way that breached your Charter rights. If a Charter breach is proven, a judge can exclude the results under section 24(2). Whether that happens depends on the evidence and the facts of your case.
What if police did not tell me about my right to a lawyer?
Section 10(b) of the Charter gives you the right to retain and instruct counsel without delay and to be told about that right when you are arrested or detained. If police failed to inform you, delayed without good reason or did not let you speak to a lawyer, that may be a Charter breach. Evidence gathered afterward, including breath results, may then be excluded.