Whether the trial judge intervened in the trial in a manner that undermined the fairness of the trial or led to a reasonable apprehension of bias, warranting a new trial. First, by intervening in and limiting cross-examination. Second, by “entering the fray” and creating a reasonable apprehension of bias. Third, by limiting submissions on a defence raised.
With respect to the intervention in cross-examination, the ABCA set out the test:
Interjections during the cross-examination of the prosecution’s witness may amount to trial unfairness, either actual or perceived. The test to determine whether such interventions compromised trial fairness is an objective one. “The ultimate question to be answered is not whether the accused was in fact prejudiced by the interventions but whether he might reasonably consider that he had not had a fair trial or whether a reasonably minded person who had been present throughout the trial would consider that the accused had not had a fair trial”: R v Valley,  OJ No 77, 26 CCC (3d) 207 at 232, leave to appeal to SCC dismissed  SCCA No 298 (QL). [@21]
With respect to entering the fray and creating an apprehension of bias, the ABCA set out the test:
When undue intervention is advanced as a ground of appeal, the ultimate question is whether the comments and interventions would create the appearance of an unfair trial to a reasonable person present throughout the trial proceedings. A trial judge must not question a witness in such a way as to convey an impression that the judge aligns himself or herself with the case for the Crown or the defence; question a witness in such a way as to make it impossible for counsel to present their case; or intervene to such an extent in a witness’s testimony that it prevents the witness from telling his or her story. Context is critical in assessing whether trial unfairness through undue intervention or a reasonable apprehension of bias have been made out. The impugned comments and interventions that are alleged to have compromised trial fairness or showed a reasonable apprehension of bias must be analyzed in light of the surrounding context and the particular facts of the case. [@39]
With respect to limiting a defence, no test was expressly set out.
The Fine Print
The Supreme Court agreed with the majority of the ABCA. That court held as follows.
With respect to the interventions in cross-examination, the court held that the trial judge is obligated to manage the trial and in this way is permitted to asked counsel to focus or move along. Here the relevance on the impugned line of questions was not clear and the trial judge’s interventions were not inappropriate. A reasonably minded person present throughout the trial would not consider the interventions to have rendered the trial unfair.
With respect to entering the fray and creating an apprehension of bias, the court held that trial judge did so on multiple occasions but must were largely for the purpose of clarifying the evidence. The interventions do not suggest a bias on the part of the judge. While it may have been preferable to adopt a more “restrained approach” the interventions do not give rise to a reasonable apprehension of bias.
With respect to limiting a defence, the ABCA held that the accused was not prevented from relying on a defence (honest but mistaken belief) and the trial judge ruled on it.