Rebutting The Breathalyzer Presumptions

In R. v. Cyr-Langlois,1 the Supreme Court of Canada offered clarification on the type of evidence that is required to rebut the presumptions of accuracy and identity applicable to breathalyzer test results under section 258(1)(c) of the Criminal Code ("Code").2 In doing so, Wagner C.J., writing for the majority, confirmed that the evidence must amount to more than conjecture or speculation. This case is significant for defence lawyers, as it demonstrates that an accused will likely need to adduce concrete factual evidence in order to rebut the breathalyzer presumptions.

Statutory Presumptions

Section 258(1)(c) of the Code contains two presumptions applicable to breathalyzer results: the presumptions of accuracy and identity. According to the presumption of accuracy, the certificate of the technician responsible for administering the breathalyzer test is presumed to provide an accurate determination of the person's blood alcohol level ("BAC") at the time that the breath samples were taken.3 According to the presumption of identity, a person's BAC as shown by the test results is presumed to be the same as his or her BAC at the time of the alleged offence.4 If an accused produces evidence that casts doubt on the reliability of the test results, the presumptions may be rebutted.

Facts and Case History

The accused, Marc Cyr-Langlois, was stopped by two police officers while driving. He was arrested at the scene and was taken to the police station. The accused received two breathalyzer tests at the...