What’s the difference between “Impaired Driving,” “Over 80” and “Refusal”?

Understanding the different Drinking and Driving infractions in Ontario, Quebec and Canada.

Many people call me up and want to know the difference between “Impaired Driving” and “Driving Over 80” (over the legal limit). Even more people who come into my office don’t even know there’s a difference between impaired and over 80. This article is meant to help you understand the different types of alcohol related driving offences which exist in Canada. Also note that, although impairment by drug is a similar offence, this article is mainly dealing with alcohol consumption driving cases.

DUI, DWI, Impaired

For starters, it is important to realize that there are a lot of slang terms which don’t technically apply to Canadian law. Take for example DWI and even DUI. “Driving While Intoxicated” and “Driving Under the Influence” are not Canadian crimes. To be sure, most of the time when people talk about these in Canada, they are talking about a similar or related type of driving offence, but strictly speaking it is not against the law to drive if you are intoxicated or under the influence. The touchstone as to what makes it illegal is if you drink a quantity of alcohol which not only affects you, but impairs your ability to operate a car. In many cases this may be the same thing – but it is possible that they may be different. For this reason, it is important that we use the correct terminology so we know what it is we are targeting (or avoiding) when making arguments in Court.

Impaired Driving

This is an offence under section 253(1)(a) of the Criminal Code of Canada (formerly 253(a) prior to 2008). This occurs when you consume any quantity of alcohol (or a drug) which negatively impacts your ability to drive, and you drive. The impairment to ability could come in the form of diminished reflexes, bad judgment, or loss of physical coordination.

Generally speaking, proving impairment requires circumstantial evidence. What is circumstantial evidence? Check out an earlier article of mine about circumstantial evidence.

Why are these cases circumstantial? Simply because it is virtually impossible for you to be hooked up to some kind of brain probe to measure the effects of alcohol in any kind of reliable way at the time of driving, and even if it were possible, how would the police get this data and what expert would be able to interpret it? Therefore, impairment is proven circumstantially, using common sense inferences. You see a person, they smell of alcohol and they got into an accident. So what? Sober people get into accidents, too, and just the smell of alcohol or even consumption of alcohol doesn’t mean impairment. Well, how about if this person is slurring their speech? This, too, is somewhat equivocal. But they got out of the car and had to steady themselves using the car door and then walked in a staggering manner over to the police officer. Etc. etc. etc.


There comes a point, when you add everything up, where the only reasonable conclusion is that the person was impaired by alcohol. Of course, adding explanations into the mix sometimes hurts a prosecutor’s case. You steadied yourself as you got out? That’s because the car was on an incline and the pavement was full of potholes. You staggered while walking? Maybe your foot was asleep. At the end of the day impairment must be proven beyond a reasonable doubt in order for a person to be found guilty. Probably guilty or likely guilty is not sufficient.

Lastly, it is important to know that even if you are under the legal limit, you could still be found to be impaired and therefore breaking the law. In some cases the prosecutor will tender a report from a toxicologist who will write that based on their review of leading scientific literature, impairment can occur at times in very low concentrations of alcohol and, by .05 (50 milligrams of alcohol in 100 millilitres of blood) a person would be impaired. Note, this conclusion is typical for reports from toxicologists in the Centre for Forensic Sciences and it means they suggest that you’d be impaired, every time, even below the legal limit. So remember, if you are a lightweight when it comes to drinking, you could be impaired even if you are well below the legal limit.

Over 80 mg

Conversely, if you can hold your alcohol really well, you may not be impaired (or may not show enough signs of being impaired to allow a judge to be sure) but you could be over the legal limit. I have had clients who are double, triple, and even quadruple the legal limit who did not show any signs of impairment. Typically, very high breath readings without signs of impairment occur when a person is a seasoned drinker (or an alcoholic). So even if you are walking fine, talking fine and – most importantly – driving fine, if your alcohol content is above .08, you can be found guilty.

This is typically measured by a breathalyzer (an approved instrument like the Intoxiliser 8000 C or the Datamaster) and related back to the time of driving either by a toxicologist making the calculations, or through a rule in the Criminal Code that says ‘what you blew at the station, you were at the time of driving.’ This rule is called a presumption. A presumption can only work if the criteria for its validity are met. In Canadian cases this means a first breath sample was taken within two hours of the alleged driving conduct (or care or control) and that both samples are taken in a reasonably prompt manner (as soon as practicable). Once that is proven, the only way you can avoid the charges is by either casting doubt on the reliability of the result, or by having the evidence excluded (thrown out) due to police officers not following the rule.

The first approach (cast doubt on the reliability of the result) is usually a sucker’s bet. Don’t get me wrong, I always investigate every case and, in some specific cases, will hire an expert of my own to take an even closer look. But that said, the Courts have not been kind to arguments suggesting operator error or machine malfunction. I once saw in Court, while waiting for my turn for a case, a judge delivering a judgment in a colleague’s case. The evidence in that case was that the officer was pounding on the breathalyser like a broken television set from the 1950’s because it wasn’t working at first. But once it turned on – the judge’s decision stated – it passed all its quality control checks. Although this area of the law is a barren wasteland of failed defences, there are still sometimes small technical evidentiary issues that may arise when a police officer does not describe the workings of the machine (or his/her own qualifications) sufficiently, but these successes are few and far between.

The more common way to beat an over 80 charge is to not have breath samples to begin with. And if they do exist, I often try (and am frequently successful) to ask a court to exclude the evidence (to suppress it or throw it out) since the police did not follow the applicable rules. People often ask me what technicalities exist in drinking and driving cases, or can a DUI case be thrown out on a technicality in Canada. It is important to note that this kind of procedure (excluding evidence) is not a technicality. It is a body of law that deals with real substantive issues.

We do not live in a police state and police officers cannot seize bodily substances from you without a warrant unless there is some other valid legal authority to do so. Breath samples may not be as intrusive and private as hair, blood or semen but it still comes from your body. Add insult to injury that this substance, being seized from your body – without a warrant – is then used to prosecute you in Court. This can only ever be allowed in Court where the police followed the rules that permit them to do this. The rules are numerous and too many to discuss here, but they often relate to the timing of things being done, whether the police had sufficient information to take various steps in the investigation, whether they provided and facilitated certain rights and also whether they respected other rights and freedoms of a detainee while that person was in custody.


“Fail or refuse breath sample” also known as “refusal” is when you have not provided a breath sample when requested to do so. What you need to know is that – to the police – if the machine doesn’t register a sample, you’re going to get charged 99% of the time. Too many people before you have faked asthma, emphysema, illness, injury, or simply just protested that they were doing their best and don’t know why the machine isn’t working. Most of those people were lying. So the police generally don’t consider your story, or even your intention. Most officers will say that even a toddler or elderly person can provide a sample, so if you’re not getting a valid reading, to them, you must be causing this result.


There are certain medical reasons, or legitimate reasons not to provide (i.e. the only mouthpiece available fell on the floor and you feel that it is unsanitary to use). Note that it had better be good – because the police won’t accept it as a good reason either way, and if it isn’t really a good reason, a judge won’t either. What constitutes a good reason (also known as a “reasonable excuse”) is a debatable issue and there are some cases which say what is, what isn’t, what can be, and what can’t be a reasonable excuse. For instance “a lawyer once told me I didn’t have to in these circumstances” is generally not a reasonable excuse. Note also, that unlike most criminal accusations where the prosecutor needs to prove everything to a high level of certainty, they do not need to prove the absence of a reasonable excuse; you need to prove that you are telling the truth and that your excuse is valid.

One way to attack such a case is to say the prosecutor has not proven, beyond a reasonable doubt, that you had a guilty intention. You should know there is currently a debate among judges about the definition of intention for this kind of case. In the camp of judges who are wrongly applying the law (Justice Michael Code is the leading jurist in this camp) are those who say simply being aware that the machine is not registering a reading is sufficient. Justice Paciocco (with the backing of other Superior Court cases equal to the wrong line of cases inspired by Justice Code) has addressed the law in this area. Criticizing Justice Code and his colleagues who share his view is not intended to be disrespectful, but simply, it is a travesty of justice that a person could ever be convicted of criminal wrongdoing without intending to bring about the wrongdoing (absent a specific reason for that to occur). To illustrate the point, I once had a client where the OPP officer – following his departmental policy – charged a client of mine because she was blowing but the machine did not register. Thankfully, that officer testified fairly and honestly to the effect ‘it surprised me that she didn’t get a reading since it seemed to me she was trying sincerely and following my instructions’. Thankfully – even though this case of mine preceded the Paciocco line of cases – the judge acquitted her and found her not guilty of refusing a breath sample.

Another way to attack the case is to look at some of the same rules which govern officers which – if broken – can result in breath samples being excluded. Why? Because if the rules weren’t followed, in many cases the demand for breath was not lawful, and it is not illegal to fail or refuse to provide a breath sample demanded unlawfully. For example, I can’t say “Give me a breath sample.” Similarly, a police officer who has no reason to suspect you were driving can’t do that either.

“Refusal” and “Failure” are often used interchangeably. Generally speaking the cases are called “refusals” but a true refusal is saying “I’m not going to blow” or simply not making an effort. A “Failure” happens more commonly when a person is feigning (faking it). To deal with this, officers will often give multiple chances and clear instructions.

David Anber

David Anber

David Anber has been a trailblazing legal practitioner since 2006. His early entry into law practice during his studies marked the beginning of a distinguished career. As a member of both Ontario and Quebec’s bar associations, David excels in defending traffic and criminal cases across both provinces. David contributes to legal discourse through articles for the Defence Counsel Association of Ottawa and the Criminal Lawyer’s Association of Ontario.