Justice Paciocco, author of The Law on Evidence, recently rejected the testimony of an accused person about how much he had to drink in an Ottawa drinking and driving trial. Notably, Justice Paciocco rejected the accused’s testimony largely based on the testimony of the Crown’s toxicology expert on the reliability of the Intoxilyzer 8000C.


The accused gave breath readings of 122 milligrams of alcohol in 100 millilitres of blood (mg%), and 114 mg% at the police station.  By contrast, based on the amount of alcohol the accused testified he consumed, he would have had a blood alcohol content of no higher than 50 mg%.

The first breath reading was taken more than two hours from the time of driving. As a result, the presumptions of accuracy and identity in the Criminal Code did not apply.  So, the Crown was required to call expert evidence to calculate the accused’s blood alcohol content.


In R. v. Meranger, 2013 ONCJ 567, Justice Paciocco noted:

[26]      In the days when the Carter defence applied, had the Crown been relying upon the presumptions in section 258(1)(c) I would not have been permitted to consider the Intoxilyzer readings in evaluating Mr. Meranger’s testimony: R. v. Boucher 2005 SCC 72 (CanLII), 2005 SCC 72 at paras. 43 and 64, and see R. v. St-Onge Lamoureux at para. 9. The reason was that doing so would have been hopelessly circular; it would have been boot-strapping of the highest order for the Crown to rely on the accuracy of readings in an effort to benefit from a presumption that those readings are accurate. One would have to assume what one is trying to prove in order to prove it. There is no similar illogicality in considering readings when an expert witness testifies to their accuracy, in assessing the contrary testimony of an accused person. In such a case, a Court is simply evaluating all of the evidence in context. For this reason there is no prohibition against a Court considering otherwise reliable and credible approved instrument readings in evaluating the drinking pattern testimony of accused persons where the presumption of accuracy is not being invoked by the Crown: R. v. Kernighan (2010), 257 C.C.C. (3d) 12 (Ont.C.A.).

[27]      Nor does it contravene the admonition in R. v. W.(D.) supra, against treating a case as a credibility contest, to evaluate the Crown evidence and the defence evidence in the context of one another. The admonition against engaging in a credibility contest is meant to prevent decision-makers from convicting because the Crown evidence is better, without remembering to ensure that the Crown evidence must prove guilt beyond a reasonable doubt.

In assessing the accused’s credibility, and ultimately rejecting his drinking scenario, Justice Paciocco stated:

[28]      The pay-dirt question, then, is whether Ms. Martin’s evidence and Cst. Scott’s evidence is credible and reliable enough to prove the case for the Crown, in the face of Mr. Meranger’s testimony to the contrary. This necessarily entails a comparative evaluation of the Crown and the defence evidence, bearing in mind that at the end of the process to secure a conviction, the Crown evidence must be sufficient in the face of the defence evidence to prove guilt beyond a reasonable doubt.

[39]      I therefore have before me facially credible and reliable expert evidence that the Intoxilyzer 8000C when operated properly and operating properly produces reliable results. I also have evidence of similar quality before me that in this case the Intoxilyzer 8000C was operated properly and operating properly. I have no evidence of any errors or problems caused either by the operator or by the machine. And as just indicated I have compelling evidence that if the readings in this case are accurate, Mr. Meranger’s blood alcohol level was over the legal limit at the time of driving. This evidence together is inconsistent with Mr. Meranger’s version of events, given that his version of events simply cannot produce the readings that this apparently reliable, properly operated and properly operating machine produced in his case.  In turn, Mr. Meranger’s evidence is inconsistent with the implications of this expert evidence because if his drinking pattern evidence is credited, the readings cannot be accurate in spite of the scientific offering by the Crown.

[40]      I have considered all of this evidence together and conclude that I do not believe Mr. Meranger’s inconsistent and unconfirmed account of his drinking pattern. Indeed, given its frailties and the quality of the Crown evidence that I have recited here I am not left in a reasonable doubt by Mr. Meranger’s testimony. In contrast, I do believe beyond a reasonable doubt the testimony of Ms. Martin and Cst. Scott that I have recited here. This evidence is too compelling and credible to be weakened materially by Mr. Meranger’s testimony. I therefore find that Mr. Meranger’s blood alcohol exceeded the legal limit while he operated a motor vehicle on Rideau Valley Road in the City of Ottawa on 24 February 2013. I believe the Crown evidence and accept the opinions it is based upon. I find Mr. Meranger guilty of the offence contrary to section 253(1)(b) of the Criminal Code of Canada, as charged.

How can an accused raise a reasonable doubt?

This case is troubling in the following sense:  it implies that when a toxicologist testifies, an accused’s drinking scenario will not be accepted by a court unless they can show that the Intoxilyzer malfunctioned.  In other words, an accused’s testimony on its own will not be enough to undermine the machine’s breath readings. Alternatively, the case implies that at the very least an accused person’s drinking scenario will have to be confirmed by other evidence (for example bar receipts or other witnesses).

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