skip to Main Content

BAC Test is perfect ? We think not. 

The Law

To curb impaired drivers, Parliament enacted Bill C-46 (Bill), stipulating stricter penalties for the offenders. The offence of operating a motor vehicle while impaired is enumerated under Section 320.14(1) of the Criminal Code of Canada (“CCC”). The maximum penalty for the offence is ten years imprisonment, and can be prosecuted either summarily or by indictment.

The Bill amended the culpable legal limit to 80 mg of alcohol in 100 ml of blood. Before the amendment, the legal limit was over 80 mg of alcohol in 100 ml of blood. As a result, per se, 80 BAC is now punishable while keeping no room for a margin of error. The Parliament statutorily presumed and recognized the Blood Alcohol Test (BAC) instruments, which calculate breath alcohol, to be accurate and reliable for the test.

Also, the Bill categorized the offence of impaired driving as serious criminality under the Immigration Law. Any non-citizen, including Permanent Residents, can be found inadmissible under Section 36(1) of the Immigration and Refugee Protection Act (“IRPA”) if they are convicted in Canada for an offence punishable by a maximum term of 10 years. It is of no consequence whether the Crown proceeds by summary or indictment.

The law demonstrates Parliament’s intent of no toleration for impaired drivers. Yet, for people in borderline cases, i.e. 80 mg of alcohol- the law can be unreasonable. A recent scientific study found that the breath instruments are sometimes, indeed, inaccurate. All of the BAC testing instruments suffer from a margin of error. The standard software mapping in the devices cannot take all the endogenous (within the human body) and exogenous (outside the body) variables into account for guessing the alcohol contents in the human body.

Guessing the BAC

It is “guessing” because the instruments multiply the breath alcohol by a predetermined factor to calculate the “Blood Alcohol.” This multiplication factor is known as the “Partition Ratio.” According to this theory, if one took 2100 cubic centimetres of deep lung air and analyse the amount of alcohol in that sample, the amount of alcohol would be equal to the amount of alcohol in one millilitre of blood. On the contrary, recent studies have shown that the human partition ratio can vary from 990 to 3005. Consequently, a person’s breath test sample will be artificially high if he has a partition ratio lower than 2100. This can lead to a situation where a person is convicted for per se BAC limit of 80 mg when his actual alcohol level is much less than that.

What are the ways out?

The best possible way to determine the alcohol level is a blood test rather than a breath test. We need to keep in mind that a CCC conviction, apart from the punishment, carries with itself significant stigma. A blood test is the “Gold Standard”; it is always accompanied by a margin of an error report. In a perfect world, human alcohol should be determined by a blood test. But a blood test is a resource-intensive and highly invasive practice. It is unfeasible for testing a large number of impaired drivers caught every day on the road(s) of Canada.

Therefore, the most prudent way forward is a breath test supplemented with a margin of uncertainty report. The uncertainty report will prevent the conviction of individuals who fall over or on the legal BAC limit due to the machine’s error. Such individuals do not have the moral or legal blameworthiness to be convicted under the CCC.

More reasons for an uncertainty report

Apart from the Partition ratio, as discussed earlier- various other variables necessitate re-thinking the law. For example, the temperature of an individual’s breath is incredibly essential. Our body emanates alcohol in many ways- expiration is just one of them: higher the temperature, higher the diffusion of alcohol out of the blood. The approved devices presume a standard body temperature of 34 C. On the contrary, the human temperature is a variable- not a specific. An increase of 1 C, due to a mild fever, can inflate the test results by 3-7 %, which can morph a simple HTA offence into a serious criminality offence under CCC or IRPA.

Additionally, the way the person blows air into the machine also impacts the machine’s readings. Experts at the University of Washington have confirmed that the breathing technique plays a significant role. If a person holds their breath or is a shallow breather (people with smaller body structure), their test results can be 20 percent higher than their actual BAC.

Then, there are the exogenous variables that distort the results. A flawed calibration or an unskilled operator who fails to notice a belch by the offender aggravates the uncertainty further. The fundamental flaw is that the instruments work on the “one size fits all” principle. However, the reality is that everyone is unique, and one size fits one.

We at Aitken Robertson believe that everyone has a fundamental right to good science. We believe that criminal convictions for BAC offences should be a matter of “precise” measurement. Our team is ready to go the extra mile to fight for your rights. 


Share This Post

Request Free Consultation
Back To Top