Prohibition against using breathalyzer readings in assessing credibility applies only to those cases in which the accused challenges the presumption of accuracy

R. v. Kernighan, 2010 ONCA 465, released online today, holds the prohibition against using breathalyzer readings in assessing credibility applies only to those cases in which the accused challenges the presumption of accuracy. The Court writes:

[14] The presumption of accuracy relates to the accused's blood alcohol concentration at the time the breath sample was taken. Challenging this presumption requires adducing some evidence that the certificate does not in fact correctly reflect the accused's blood alcohol level at the time of the breathalyzer test: see Boucher, at para. 21. The presumption of identity, on the other hand, relates to the accused's blood alcohol concentration at the time of the offence. Challenging the presumption of identity requires adducing some evidence to suggest that the accused's blood alcohol concentration at the time of the offence was not the same as it was at the time that the breath samples were taken: see Boucher, at para. 19.

[15] The presumption of accuracy allows the Crown to file the certificate of the breath technician as proof of the appellant's breath sample readings without having to call the breath technician as a witness in the trial (s. 258(1)(g)). In the present case, the Crown chose to call the breath technician as a witness and, therefore, did not rely on the presumption of accuracy. It relied only on the presumption of identity, contained in ss. 258(1)(c) and (d.1), to establish the blood alcohol content at the time of driving.

[16] In my view, Boucher and subsequent case law make clear that the prohibition against using breathalyzer readings to assess the accused's evidence to the contrary applies only to situations in which the Crown is relying on the presumption of accuracy and the accused is challenging that presumption.