Drinking and Driving Offences
Kenneth W. Golish, Criminal Defence

Drinking and Driving Offences

Please note the disclaimer that nothing in this site constitutes legal advice.  If you would like to have a consultation, please contact me.  Because of major changes in the law, this article is substantially different from its first iteration.

Being convicted of a drunk driving offence is a criminal matter in Canada governed by the Criminal Code.  It provides a minimum fine of $1,000.  That is on a first offence.  Subsequent convictions carry minimum jail penalties.  A conviction will also require a mandatory driving prohibition in which a person may not drive anywhere in Canada on a street or highway, for a minimum of one year, or three months in a province that has an concurrent ignition interlock program.  The law refers not only to motor vehicles, but any conveyance: This includes anything that is motorized, an aircraft or a water vessel.  In theory then, this could refer to a canoe, or a wheelchair with a motor, and offence can be committed anyway, including off-road and on private property. This article relates only to driving offences.

A Criminal Code sentence is not the only consequence: For one, the offender’s driver’s license will be suspended by the province in which the person resides for a least the period covered by the driving prohibition.  Moreover, motor vehicle insurance coverage and premiums will be impacted.  For instance, in Ontario, if the offender’s car is damaged because of an accident when the driver was impaired, the offender is not entitled to collect collision damage from the insurer.  If the offender is injured as a result of the accident, they may not receive certain no-fault benefits, although some, at least in Ontario, will be available in any event.  Even if there is no accident or injury, the driver is still looking at paying a significant amount in increased insurance premiums once they can drive again.  In Ontario, as in at least most if not all jurisdictions in Canada, there is an ignition lock programme--required after the suspension period--in addition to the remedial program instituted in 1998, including an early interlock programme.

One can be impaired by alcohol or by a drug or a combination of both.  This article will not get into the complications involved in charges of impaired operation by drugs.  Instead it will cover the three basic Canadian drunk driving offences: Impaired driving, driving with more than 80 milligrams of alcohol in 100 milliliters of blood (Over 80) and refusing to provide a breath sample, either in the form of a roadside screening device, or an approved testing instrument.  Because of the concern for keeping dangerous drivers off the road, these three offences give police and prosecutors powerful tools to combat the problem or perceived problem of drunk drivers.

We begin by describing the difference between the offence of impaired driving and the offence of Over 80.  Impaired driving does not require proof of intoxication, but merely that a driver’s ability to operate a conveyance to any degree is impaired by alcohol or a drug.  On the other hand, the offence of Over 80 does not require proof of impairment of any kind, only proof of the prescribed level of alcohol in the blood.

The offence of refusing a breath sample, either a roadside screening device or an approved instrument, rounds out the trio by maintaining prosecution options as an alternative process for those who would likely blow over the limit, but who choose not to co-operate with the police.  The consequences of a conviction on only this charge are essentially the same as those for a conviction on impaired or Over 80, namely, a criminal conviction, driving prohibition, license suspension and the same insurance consequences.

Theoretically, a person may be guilty of one offence and not the other, and of course, both.  It is permissible to charge both impaired driving and Over 80.  A rule of law, however, similar to the doctrine of double jeopardy, prevents simultaneous convictions for both impaired driving and Over 80.  Nevertheless, the same rule does not prevent an individual from being convicted of both impaired driving and refusing a breath demand, although this will not result in a double suspension.

Stopping a Motorist, from traffic stop to conviction: In Canada, police are given a wide latitude to stop drivers.  They may always stop drivers for observed driving infractions, including seat-belt infractions, vehicle safety concerns or if they reasonably believe a driver--or likely a passenger as well--is committing or has committed a criminal offence and is subject to arrest with or without a warrant.  Police may also set up stop points to pull vehicles over to check for license and insurance and as part of a program to reduce drunk driving, known as R.I.D.E.  (Reduce impaired driving everywhere).

The roadside is not the only place where the police come in contact with a suspected offender.  Where an accident happens, the operator may end up at a hospital, where the police will go to investigate.  Also some individuals choose to voluntarily leave the scene, so it is not unusual for the police to show up at the residence or other location of a person who will later be charged. 

In any of these cases the police may require a driver to comply with screening procedures for alcohol or drugs, including performing physical coordination tests, breath samples and samples of bodily substances.  The officer may make such a demand where there are reasonable grounds to suspect that a person has alcohol or a drug in their body and that the person has, within the preceding three hours, operated a conveyance.[1]  Moreover amendments introduced in 2018 appear to go further permitting the use of a screening device in the absence of any suspicion, if the law otherwise authorizes it.

The results of a roadside screening device for alcohol are either a pass, warn or fail.  The machine is usually calibrated to fail when a person has over 100 milligrams of alcohol in 100 milliliters of blood.  Willfully refusing to provide a sample is a criminal offence but failing the test is not.  Evidence of a failed reading is not evidence of the level of alcohol in the person’s blood.  It is only used to justify a further demand for an actual sample into an approved instrument.

Upon arrest or detention an individual is entitled to be informed of the right to counsel, the availability of a 24-hour toll-free legal aid number, and the right to contact a lawyer.  If the police do not give a person under arrest the opportunity to contact counsel, the failure to do so may result in the exclusion of evidence, namely, the result of the defendant’s alcohol level readings obtained from an approved instrument.  The right to counsel however is not available at the time of a roadside demand, although in some instances the police upon request might permit it. 

Proving impairment: When police officers make reports of impaired driving incidents they frequently use the same language to suggest alcohol impairment.  The signs of alcohol impairment include this non-exhaustive list:

Driving observations:


·         Erratic driving;

·         Slow driving;

·         Fast driving;

·         Crossing centre line or going over edge of roadway;

·         Weaving in lane;

·         Involvement in an accident.


Personal Observations:


·         Alcohol breath;

·         Bloodshot eyes;

·         Sobriety tests, when performed;

·         Unsteadiness; and

·         Slurred speech.


At least in this part of Ontario, where courts have not demanded that the police employ these practices, police do not necessarily request sobriety tests as part of the arrest routine.  They can however demand an individual submit to those tests nonetheless.

Other that the physical evidence listed above, in deciding if a person is impaired, the courts may also rely on the testing evidence other than from a screening device, as well as the fact that a person refused to comply with a lawful demand

The prosecution may prove impairment by any combination of factors.  The absence of one factor certainly does not mean the prosecution hasn’t proven its case.  The presence of numerous factors will make the defence case difficult.  However, often the defence may have reasonable explanations for these observations.  For instance, blood-shot eyes may be a product of lack of sleep, unsteady gate a result of an injury.  Even the smell of alcohol is not conclusive.

Refusing to provide a breath sample: Where the defendant refuses to provide a breath sample, the prosecution is able to achieve its purpose by having a substitute charge available with the same consequence following upon conviction.  The refusal must be willful and without justification or excuse.  This is really not difficult for the prosecution to establish and as a practical matter, it is essentially for the defendant to establish that there was not any willful effort to avoid providing a sample.

Breath testing instruments: The results of breath testing instruments are the most decisive factors in a drinking-driving prosecution.  The prosecution is entitled to the use of a short-cut to prove the level of alcohol in a person s blood.  Although breath testing instruments measure alcohol from the air in the subject s lungs, the science of breath testing is based on a direct correlation between the level of alcohol there and in the blood.  To take advantage of the short-cut, the prosecution must show that at least two tests were taken as soon as practicable.  Formerly the first had to be within two hours of the alleged time of the offence in any event, but that requirement was removed.

Blood or urine testing: The use of blood or urine samples may be required in certain circumstances.  A person suspected of impaired driving or Over 80 however does not have the option of choosing the testing method.

Care and control: To be guilty of these offences, it is not necessary for an individual to actually be driving.  It is sufficient, if the person is in care and control of the vehicle.  Care and control has a broad meaning.  Thus a person could be guilty merely when they intend to drive:  Walking to a vehicle, keys in hand, may be enough proof of that.  Still, the prosecution must prove care and control.  When a person occupies the driver’s seat, however, the Criminal Code provides a presumption of care and control. 

Defending drunk driving cases: Many drunk driving cases can be won and depending on the case, different approaches may apply.  There are technical arguments which may result in a winning case.  An experienced lawyer will be able to identify them if they are there.  This will happen if the police or the prosecutor make some error, leaving it open for the defence to take advantage of that situation. 

The charge of impaired on its own: Evidence of impairment may frequently be explained away because just about any indicator of impairment, by itself, may be explained away by some other factor.  For instance, if the police officer says a driver’s eyes were bloodshot, that can easily be because the person hasn t slept in 24 hours.

It is only necessary that the defence raise a reasonable doubt about the issue of impairment and the judge must dismiss that charge.  Because Over 80 is usually prosecuted with impaired driving, however, the defendant needs to succeed on the Over 80 charge as well.  Sometimes, an Over 80 charge will fail for the prosecution when some technical point is missed.  As the prosecution must be detailed in presenting its Over 80 evidence, it is possible for something to be missed and the defence may succeed on that ground.

Even when the prosecution’s case is solid, however, some room for a defence is still available.  First, it is possible to be keep the breath sample evidence out completely.  Although, other circumstances may arise, the defence may be able to exclude the introduction of the breath test because the defendant has been denied some constitutional right, typically the right to counsel.

The right to counsel has two basic components, the informational component and the access component.  Not only do arrested people have a right to speak to a lawyer, they must be informed of that right.  The informational component arises because the right to access a lawyer will be meaningless without the knowledge of that right.  As part of the both components, the police are required to advise an arrested individual of the availability of access to free duty counsel advice and of course, allow access to such services, at least where the provincial legal aid plan has such a service in place

It is not unusual for the police to ignore or forget some aspect of these constitutional requirements.  As such, when a court makes a finding that a defendant was denied the right to counsel, the court is likely to exclude the breath testing results.  A caution is necessary, because, even when there has been a breach of a constitutional right, there may still be the discretion to admit the tainted evidence nonetheless.

Over 80 provisions before 2008: This used to be a path to a valid defence in Over 80 cases.  This was before 2018, but it is probably not a valid defence any longer.  The level of alcohol in a person’s blood will depend on three major factors starting with the amount of alcohol consumed and the body mass of the person consuming the alcohol.  Liquor, wine and beer all contain different percentages of alcohol and each category of alcoholic beverage, the percentage will also vary depending on the brand or type of drink.  It is thus the actual volume of pure alcohol an individual drinks that is the starting point for the level of alcohol in the blood.  The second factor relates to the mass and physiology of the person consuming the alcohol.  As a basic rule, the amount of blood volume will largely depend on the person’s height and weight.  Thus a person with a larger body will need to drink a greater volume of alcohol in order to have the same blood alcohol level as a smaller individual.  Obviously, the final major factor was time.  Consumed alcohol will take a certain number of minutes to be absorbed into the body.  It will then be eliminated over a period of time.  As a general rule, the rate of absorption is faster than the rate of elimination.  For this reason, in most instances, a person’s blood alcohol level is likely to be lower when he or she takes a breath test after being arrested. 

The Criminal Code used to provide that as long as at least two breath tests were taken as prescribed, the lower reading was considered to be the level of alcohol at the time of the offence for which the person was charged.  The defence used to be entitled to establish that the level of alcohol could have been lower at the time of driving.  This was called a Carter defence.   To do this, the defence usually only had to provide evidence regarding how much alcohol the defendant consumed and when.  This evidence analyzed by a toxicologist could verify what the blood alcohol level would have been different than the reading on the machine at the time of the driving or care and control.  The key to this defence was that the evidence of alcohol consumption had to be accepted that it could be reasonably true.  If the evidence is rejected because the witnesses not believed, then there was no evidence to the contrary and the case failed.  In 2008 this defence was eliminated.

Establishing alcohol consumption may be problematic because, in most instances, it is difficult to independently verify the assertion of the defendant concerning how much they drank.  Even the evidence of others who were in the company of the defendant may not be given significant weight because such evidence usually comes from a source- -usually the defendant’s friends, family or co-workers- - whose bias cannot be ignored.

The Catch: Before 2008, often such evidence had a Catch-22 as the weight of authority favoured the court being able to use the breath reading itself as a consideration in deciding whether the defence had established evidence to the contrary.  As a practical matter, this limited the use of the defence to two circumstances.  In one, when the breath reading was low, for example 110 or less, in which case the defence could argue more credibly that it was possible that actual level of alcohol was under 80 at the time.  The other occasion for raising the defence was when the reading was high, when the most of the classic signs of impairment were not noted, classic signs such as erratic driving, blood-shot eyes, alcohol the breath, etc.  Nonetheless, before 2008, the Carter defence often succeeded.  Reasonable doubt prevailed despite the wide-spread belief, particularly among prosecutors, that defendants were for the most part not being entirely truthful during the course of trials.

With the Carter defence the evidence suggested that the breath testing must have been flawed without independent proof.  The law however changed to provide that the analysis of alcohol established by the prescribed procedure was conclusive proof of the concentration of alcohol resulting from that analysis and that evidence to show the instrument was malfunctioning could not be include evidence of the amount of alcohol consumed, the rate at which the defendant absorbed or eliminated alcohol, or a calculation of what the defendant’s alcohol level would have been at the time of the alleged defence.

The Last Drink Defence and Drinking after driving: It was still however possible to make out the defence if one was not in essence challenging the accuracy of the reading itself.  In what is known as the last drink defence, the defendant simply argued that given the pattern of drinking, although the machine may have accurately reflected the defendant’s blood alcohol at the time the tests were taken, at the time of driving, the level of alcohol could have been below 80.  This could happen if a person is arrested or the alleged offence occurs shortly after the last drink.  The defence will be especially strong when the defendant has more than one drink in quick succession.  It was thus possible for the level of blood alcohol to increase after the time of driving.

Of course, it was not an unheard occurrence for a person to consume alcohol after the time of the incident, typically in an accident situation, where a person goes back into a bar or home and continues the drinking he or she has already started or starts afresh.  In that situation, the defendant may have had a credibility problem, and the combination of what the prosecution could assert as a consciousness of guilty, the accident and other factors, could end up with a conviction on one charge or the other in any event.  Nonetheless, drinking after the accident, that resulted in an elevated level of alcohol, not reflective of the level at the time of driving, was clearly a valid defence.

The change in the law in 2018 takes this all away.  First off, the final breath testing can take place beyond the former two hour limit.  Moreover, when the readings are taken beyond that limit, the law permits the result to reflect a higher value to account for the elimination of alcohol at a given rate:

320.31(4)…if the first of the samples of breath was taken, or the sample of blood was taken, more than two hours after the person ceased to operate the conveyance and the person’s blood alcohol concentration was equal to or exceeded 20 mg of alcohol in 100 mL of blood, the person’s blood alcohol concentration within those two hours is conclusively presumed to be the concentration established in accordance with subsection (1) or (2), as the case may be, plus an additional 5 mg of alcohol in 100 mL of blood for every interval of 30 minutes in excess of those two hours.  [Emphasis added]

Not only is it an offence to be impaired or Over 80 at the time of driving, but it also an offence to be Over 80 within two hours after driving.[2]  In theory then, one could be under 80 at the time of driving, but still be guilty of this offence.  Obviously the law couldn’t have been intended to prohibit people from driving home and having a cocktail handed to them the minute they walked in the door.  An exception applies therefore when the person only starts drinking after operating the conveyance, they had no reasonable expectation that they would be required to provide a sample of breath or blood, and that their level of alcohol was below the legal limit at the time of driving as otherwise established.[3] 

Except for constitutional and technical arguments, it appears the only defence open to a defendant is to attack the alcohol analysis if the testing was performed improperly, but that kind of evidence may be difficult to establish.[4]

Why Retain a Lawyer? While it is very true that the odds in these cases are stacked against the defendant, it may still be advisable to have an experienced lawyer review the evidence for possible defences or errors that suggest some reasonable chance of success if the matter is taken to trial.  Whether the defendant is likely facing jail, the defendant is still looking at a significant fine and other consequences.  If ultimately you end of up receiving the same penalty you would have received without hiring a lawyer, it may be valuable to know that you made the right decision in pleading guilty.  Beyond that, frequently experienced lawyers can realize some mitigation of penalty, perhaps no jail or a lesser period in jail than warranted, a lower fine, or a shorter driving prohibition period.  In some cases, the defendant can avoid a criminal conviction, but not in the normal course, a suspension, by entering a plea to a highway traffic charge of careless driving.

See the following Ontario summary conviction appeal cases where defence prevailed on appeal.  A number involved appeals by the prosecution.  In the first three I was counsel:

R. v. Sefton, 2022 ONSC 1429 (CanLII) : Evidence excluded because of a breach of right to counsel.

R. v. Merheje, 2020 ONSC 6413 (CanLII) : Appellant acquitted when officer incorrectly put a decimal point in the wrong location on the certificate.

R. v. Drouillard, 2018 ONSC 4295 (CanLII) : Appellant acquitted on appeal on a charge or refusing to comply with a screening device demand.

R. v. Odemi, 2022 ONSC 2292 (CanLII)

R. v. Bennett, 2022 ONSC 2686 (CanLII)

R. v. Vine, 2022 ONSC 3297 (CanLII)

R. v. Edwards, 2022 ONSC 3684 (CanLII)

R. v. Abdullah, 2022 ONSC 4119 (CanLII)

R. v. Mankal, 2023 ONSC 519 (CanLII)

R. v. Ferreira-Small, 2021 ONSC 7011 (CanLII)

R. v. Skurski, 2019 ONSC 2943 (CanLII)

R. v. Jasper, 2019 ONSC 6843 (CanLII)

R. v. Mtonga, 2021 ONSC 1482 (CanLII)

R. v. Coutts, 2020 ONSC 3477 (CanLII)

R. v. Walker, 2020 ONSC 2139 (CanLII)

R. v. Ali, 2020 ONSC 1005 (CanLII)

R. v. Lavoie, 2023 ONSC 504 (CanLII)


Caution: This article has highlighted some of the issues that will arise in a drunk driving case.  It must however be read with caution, as this is a complex area.  If you are charged with such an offence, it is especially important to hire or at least consult with a criminal lawyer in the jurisdiction where the charges arise.

[1] 320.27

[2] 320.14

[3] 320.14(5)

[4] Also there may be one other way to attack the Over 80 evidence.  The science of alcohol testing is complex.  There are those who question the accuracy and validity of breath testing, which is based on an assumption, a given ratio, that the level of alcohol in an individual’s deep long air can be converted to establish the level of alcohol in the person’s blood at the time.  The science however suggests that this ratio will not be exactly the same for everyone, and for some individuals with certain medical conditions may be completely off.  So, defendants could mount a defence establishing scientifically that for them the breath readings were not accurate and in event their levels of alcohol were below the legal limit.  This defence will be rarely used simply because most individuals wouldn’t be able to establish that they were different from others.


Please note the disclaimer that nothing in this site constitutes legal advice.  If you would like to have a consultation, please contact me.