The presumption of innocence is the golden thread running through the Canadian Criminal Justice System. It is a fundamental principle of justice. As such, it is critical in any trial in which an accused person testifies that the analysis of the evidence follows an approach that respects the paramount importance of the presumption of innocence and does not transfer the onus of proof onto the accused.
These principles apply even in traffic court trials.
In R. v. Sandoval the trial court’s analysis gave the impression that the burden of proof had been moved onto the accused rather than the prosecution. Specifically, the officer had testified to the readings he obtained on a laser device. Those readings were well over the speed limit. Mr. Sandoval testified that he wasn’t speeding and used his cruise control to ensure he was not traveling over the limit. The judicial justice preferred the evidence of the officer and dismissed Mr. Sandoval’s evidence because he did not have a calibrated speedometer. In faulting Mr. Sandoval for the lack of a calibrated speedometer, the judicial justice was not at all concerned that the officer had not performed all of the manufacturer’s recommended tests prior to using the laser.
In granting the appeal the Supreme Court explained:
 It was the Crown, not Mr. Sandoval, who bore a burden of proof in the trial on the issue of speed. The Crown was required to prove beyond a reasonable doubt that Mr. Sandoval’s speed was more than 50 km/h. Despite this, the judicial justice took a much more exacting approach to Mr. Sandoval’s evidence about his speed than he did to the Crown’s evidence of the ProLaser reading, requiring almost mechanical precision of the former, while dismissing a challenge to the reliability of the latter as a result of his own review of a portion of the user manual that had not been addressed in the evidence.
 This disparate treatment of the evidence gave the impression that Mr. Sandoval bore a burden of proving that his speed was less than 50 km/h. To a well-informed, reasonable person, this would have created an appearance of unfairness in the trial…this too contributed to a miscarriage of justice.
The burden of proof beyond a reasonable doubt remains on the prosecution throughout a trial. If the court’s analysis appears to shift that burden to an accused or to scrutinize their evidence more harshly an appeal court will likely order a new trial.