A judge or a jury may accept some, none or all of the evidence of any witness at a criminal trial in Canada (e.g. R. v. J.H.S.,  2 S.C.R. 152 at para. 10). In making this determination, a judge or a jury will be alert to any concerns with respect to the sincerity and accuracy of the testimonial evidence.
The assessment of the reliability and credibility of a witness, however, is not an exact science. There is no infallible way for a judge or a jury to determine whether a witness is telling the truth, the whole truth, and nothing but the truth - there is no lasso of truth in criminal court.
So how do judges and juries go about this important task of assessing the reliability and credibility of a witness?
And how does the assessment of reliability and credibility relate to the application of proof beyond a reasonable doubt?
Subsequent posts in this series will review the factors that a judge or a jury may take into account when deciding whether the evidence of a witness is reliable and whether a witness is being truthful. The analytical framework for applying the high standard of proof beyond a reasonable doubt in the face of conflicting testimony will also be examined.
The reality is that judges or juries do the best they can with the information that counsel presents to them at trial and they may make mistakes when assessing reliability and credibility. For example, a judge or a jury may reject the truthful evidence of an accused that appears objectively suspicious, or accept the believable lie of a nefarious witness for the prosecution. Unfortunately, an accused will be in a difficult position with respect to an appeal in the absence of other errors in the trial process as appellate courts are reluctant to interfere with findings of fact made by judges and juries that appear reasonable based on the evidentiary record before the Court.