R. v. Cunha, 2016 ONCA 491:
 I accept the appellant's argument that "the trial judge parsed the appellant's reactions down to the split-second and held him to a standard of perfection, informed by his hindsight knowledge that Mr. Barros was actually unarmed and that Mr. Massaquoi had already left the house through the back door." This was an error in principle, since the trial judge lost sight of the whole factual context and the tableau of the evidence.
 This was plainly a case for the court to keep in mind that in considering the reasonableness of the defendant's use of defensive force, the court must be alive to the fact that people in stressful and dangerous situations do not have time for subtle reflection. However, the trial judge held the appellant to a standard of perfection.
 The trial judge found that the appellant subjectively feared for his life, for his friend, and for his property. He stated: "I accept also that Mr. Cunha was probably feeling fear at that time, including fear for his life and also fear for his friend Mr. Silva."
 As noted above, self-defence can be invoked on the basis of reasonable mistakes of fact. This includes mistaking whether the putative assailant was armed as was the case here. The trial judge's finding that Mr. Barros was unarmed is not fatal to the appellant's self-defence claim.
 As I see it, the trial judge effectively imposed on the appellant an obligation to wait and see whether Mr. Barros had a gun or other weapon before acting. Although the appellant had the advantage over Mr. Barros at the moment when he ordered him to freeze, he would have lost that advantage had he waited, and would have exposed himself to risk of serious harm if Mr. Barros had been carrying a gun. As this court noted in R. v. Quinn, 2014 ONCA 650 at para. 10: "This was a fast-paced event that should have not be viewed on a frame-by-frame basis."
Of the Law Societies of Upper Canada and Nunavut