Often, my partner and I have friends asking us about, “that defence where you argue your blood alcohol level is less than what the machine says it is”. We figured that we should take a moment to explain in laymen’s terms what the defence actually entails.
As a starting point, we’ll give you a typical scenario:
Please note that the quantities and measurements that we are using are approximations and are for illustrative purposes only.
You’re at a pub with some friends drinking beer. You arrive at the pub at 8:00 P.M. Between 8:00 P.M. and 9:45 P.M. you drink 3 bottles of domestic beer. At 9:45 P.M., you receive an angry call from your significant other, demanding you get home immediately. Despite this, you decide to order another beer with the intention of drinking it quickly and departing. Unbeknownst to you, your best friend ordered a round of beer as well. Knowing that your significant other is going to be upset if you’re not home in short order, you chug the two beers and leave the pub.
You get into your vehicle and proceed to drive home and are stopped by Police almost immediately. The officer suspects that you have consumed alcohol, and demands that you provide a sample of your breath into an “Approved Screening Device” (A.S.D). In this circumstance, the police are not under the belief that you are “impaired”, rather they are under the suspicion that you have consumed alcohol. You comply with the officer’s demand and provide a sample of your breath into the A.S.D. The officer informs you that you have “failed” the test and will be arrested for “Driving with Excess Blood Alcohol”. At this point, the officer advises you that you will be taken back to the police station to provide further samples of your breath into a breathalyzer. By the time you’re booked into the police station and ready to provide samples of your breath into a breathalyzer, it’s nearly 11:00pm. You provide two samples of your breath into the breathalyzer and the readings are 100 milligrams of alcohol per 100 milliliters of blood, and 90 milligrams of alcohol per 100 milliliters of blood. The officer informs you at this time that your “blood alcohol concentration” (B.A.C) is over 80 milligrams of alcohol per 100 millilitres of blood, and as a result you will be charged with “Driving with Excess Blood Alcohol/Over 80”.
The Criminal Code of Canada– Definition of Impaired/Over 80
253. (1) Every one commits an offence who operates a motor vehicle or vessel or operates or assists in the operation of an aircraft or of railway equipment or has the care or control of a motor vehicle, vessel, aircraft or railway equipment, whether it is in motion or not,
(a) while the person’s ability to operate the vehicle, vessel, aircraft or railway equipment is impaired by alcohol or a drug; or
(b) having consumed alcohol in such a quantity that the concentration in the person’s blood exceeds eighty milligrams of alcohol in one hundred millilitres of blood.
(2) For greater certainty, the reference to impairment by alcohol or a drug in paragraph (1)(a) includes impairment by a combination of alcohol and a drug
It you pay careful attention to the wording of s.253(1)(b) of the Criminal Code of Canada posted above, it’s an offence to operate a motor vehicle having consumed alcohol in such a quantity that the concentration in the person’s blood exceeds eighty milligrams of alcohol in one hundred millilitres of blood. In other words, in order for the offence to be proven beyond a reasonable doubt, your B.A.C must be over 80 milligrams of alcohol in 100 milliliters of blood at the time you operate your motor vehicle.
This is where it gets slightly complicated. Alcohol requires time to absorb into your blood stream. In the scenario that we described above, the two beers that are consumed immediately prior to leaving the pub haven’t fully absorbed into your bloodstream when you are actually stopped by the police. However, when you provide their breath samples an hour later at the police station, the alcohol has had sufficient time to fully absorb into their blood. The defence is centered on the premise that an individual who consumes a large amount of alcohol immediately prior to driving may be under the legal limit at the time of driving and only over the limit some time later, when the alcohol has had time to absorb into their blood stream. The defence is commonly known as “bolus drinking”.
Let’s use the scenario depicted above. Keep in mind, the numbers we are using are for illustrative purposes only. We are not factoring in elimination, height, weight etc., in an attempt to keep this as simple as possible.
- 1 bottle of domestic beer = 25 milligrams of alcohol
- The subject consumes a total of 5 domestic bottles over 2 hours: 25mg x 5 beers = 125mg
- Two beers are consumed immediately prior to driving and have not entered into the driver’s blood stream, as a result, the B.A.C at the time of driving is actually 75 milligrams. 125mg – 50mg = 75 mg.
Seems easy, right? Think again!
It’s not as easy as walking into a courtroom on your day of trial and saying that you chugged a micky of Jack Daniels before getting behind the wheel of your Kia. It requires much more. First, the defence requires evidence from an experienced toxicologist. The toxicologist will analyze your pattern of drinking and calculate whether or not your B.A.C would have been under 80 milligrams during the time of driving. Secondly, evidence from other parties who witnessed the rapid consumption of alcohol immediately prior to driving is also required. It is important to note however that the defence will only succeed if that “bolus drinking” scenario is believed. There have been a number of cases where it has been stated that the amount of alcohol allegedly consumed immediately prior to driving is unrealistic or abnormal. In such cases, the defence ultimately fail. Below are links to some popular “bolus drinking” cases.