Air of reality

In a criminal prosecution the Crown bears the ultimate burden to show an offence was committed, and not defence applies, to beyond reasonable doubt.

That said, a court will not consider a defence to a criminal case unless the evidence discloses the defence has an 'air of reality'. Merely asserting, say, self defence will not allow the trier of fact to consider self defence; there must be some evidence that supports, in some way, that defence.

Today's Court of Appeal decision in R. v. Mathisen, 2008 ONCA 747 sets out the test well:

(b) The Air of Reality Test

[47] A defence should be put to the jury only if it is sound in law and meets the air of reality test. The air of reality test requires that there be evidence in the record on which a properly instructed jury, acting reasonably, could acquit: see R. v. Cinous, [2002] 2 S.C.R. 3. In applying the air of reality test, a trial judge assumes that the evidence the accused relies on is true. Moreover, the trial judge does not decide the substantive merits of the defence, weigh the evidence, make findings of fact or credibility, or draw firm factual inferences: see Cinous at paras. 53-54.

[48] Thus, in performing this gatekeeper function, a trial judge must not usurp the jury's role as finder of fact. It is not part of the trial judge's role to determine whether the defence is or is not likely to succeed. "The question for the trial judge is whether the evidence discloses a real issue to be decided by the jury, and not how the jury should ultimately decide the issue": see Cinous at para. 54.

[49] Where the defence has more than one element, as do ss. 34(1) and (2), the air of reality test applies to each of the elements. If any element lacks an air of reality, the defence should not be put to the jury. Further, each of the elements in ss. 34(1) and (2) has both a subjective and an objective component. The subjective component is the accused's perception of the situation he or she confronts; the objective component requires that the accused's perception of the situation be objectively reasonable: see Cinous at paras. 93-95.