What is the case law on admitting new evidence in a criminal appeal?

With respect to this evidence, I am satisfied on a balance of probabilities that the Government has met the second, third and fourth criteria in Palmer for the admission of fresh evidence. The evidence is clearly relevant and there is no suggestion that it would not be reasonably capable of belief. Further, it could reasonably be expected to have affected the result at trial. However, the principal difficulty I have with admitting that evidence on the appeal is that it clearly could have been adduced at trial with the exercise of due diligence. I recognize that the criterion of due diligence is not a condition precedent to the admissibility of fresh evidence in criminal appeals, or quasi-criminal appeals such as this, but it remains a factor to be considered in deciding whether the “interests of justice” warrant the admission of the evidence. Indeed, McIntyre J. adopted the reasons of Ritchie J. in McMartin v. The Queen, 1964 CanLII 43 (SCC), [1964] S.C.R. 484 (at para. 775): ”… it [is] not in the best interests of justice that evidence should be so admitted as a matter of course. Special grounds must be shown to justify the exercise of this power by the appellate court…" (my emphasis)