The Appellate Law
Rule, inherent to definition
Recently, In R. v. Khan, 2019 ONCA 81, the Court of Appeal reminded of the requirement to review whether circumstantial evidence can give rise to reasonable possibilities other than guilt by stating:
 In our view, the trial judge erred in law by failing to apply the Supreme Court of Canada’s decision in R. v. Villaroman, 2016 SCC 33 (CanLII), at para. 37, where the court stated:
When assessing circumstantial evidence the trier of fact should consider “other plausible theories and other reasonable possibilities” which are inconsistent with guilt.
This reminder follows age old and well established principles that "circumstantial evidence" may be applied for a finding of guilt where rational inference supports only the presumption of guilt; Mezzo v. R.,  1 S.C.R. 802:
12. A similar question as to the scope of the trial judge's function on a motion for a directed verdict arose in the context of circumstantial evidence in R. v. Comba, supra. In that case this Court set aside a jury verdict of guilt. Sir Lyman Duff C.J. stated, in effect, that cases comprised wholly of circumstantial evidence should be measured against the rule in Hodge’s Case (1838), 1838 CanLII 1 (FOREP), 2 Lewin 227, 168 E.R. 1136. The rule states that where all the evidence is circumstantial the accused can be found guilty only if the evidence is both consistent with guilt and inconsistent with any other rational conclusion. He also remarked that this would have been an appropriate case to direct a verdict of acquittal. A line of jurisprudence subsequently developed which incorporated the rule in Hodge’s Case into the trial judge's deliberations on a motion for a directed verdict, thus creating an exception where circumstantial evidence was concerned to the narrow role of the judge at this stage of the trial.
Such was similarly said decades earlier by the Court of Appeal for Alberta in the case of R. v. McEwan, 1932 CanLII 308:
Proof by circumstantial evidence being a matter of logical reasoning from facts admitted or established in evidence there is always the danger of the tribunal of fact, whether it be Judge or jury, jumping to conclusions from certain facts without due regard to other facts which are inconsistent with the hypothesis which the first set of facts seems to point to....
There being no direct evidence, the case must rest, on the circumstantial evidence alone, and the general rule is that to amount to proof such evidence must be not merely consistent with guilt but inconsistent with innocence.
Proper Review Criteria
The assessment of circumstantial evidence requires more than just the evaluation of whether the circumstantial evidence rationally enables the inference that a possibility of guilt exists, when the circumstantial evidence is assessed such assessment also requires the review of other possibilities as per R. v. Villaroman,  1 S.C.R. 1000 where it was stated that:
 When assessing circumstantial evidence, the trier of fact should consider “other plausible theor[ies]” and “other reasonable possibilities” which are inconsistent with guilt: R. v. Comba, 1938 CanLII 14 (ON CA),  O.R. 200 (C.A.), at pp. 205 and 211, per Middleton J.A., aff’d 1938 CanLII 7 (SCC),  S.C.R. 396; R. v. Baigent, 2013 BCCA 28 (CanLII), 335 B.C.A.C. 11, at para. 20; R. v. Mitchell,  QCA 394 (AustLII), at para. 35. I agree with the appellant that the Crown thus may need to negative these reasonable possibilities, but certainly does not need to “negative every possible conjecture, no matter how irrational or fanciful, which might be consistent with the innocence of the accused”: R. v. Bagshaw, 1971 CanLII 13 (SCC),  S.C.R. 2, at p. 8. “Other plausible theories” or “other reasonable possibilities” must be based on logic and experience applied to the evidence or the absence of evidence, not on speculation.
 Of course, the line between a “plausible theory” and “speculation” is not always easy to draw. But the basic question is whether the circumstantial evidence, viewed logically and in light of human experience, is reasonably capable of supporting an inference other than that the accused is guilty.
Trial by Jury, instructions for deliberating
Where a criminal case is proceeding before a jury, where the assessment of circumstantial evidence is involved, the Trial judge is without requirement to provide the jury with "special instruction" for the proper assessment of the circumstantial evidence per R. v. Griffin,  2 S.C.R. 42 which says:
 We have long departed from any legal requirement for a “special instruction” on circumstantial evidence, even where the issue is one of identification: R. v. Cooper, 1977 CanLII 11 (SCC),  1 S.C.R. 860. The essential component of an instruction on circumstantial evidence is to instill in the jury that in order to convict, they must be satisfied beyond a reasonable doubt that the only rational inference that can be drawn from the circumstantial evidence is that the accused is guilty. Imparting the necessary message to the jury may be achieved in different ways: R. v. Fleet (1997), 1997 CanLII 867 (ON CA), 120 C.C.C. (3d) 457 (Ont. C.A.), at para. 20. See also R. v. Guiboche, 2004 MBCA 16 (CanLII), 183 C.C.C. (3d) 361, at paras. 108-10; R. v. Tombran (2000), 2000 CanLII 2688 (ON CA), 142 C.C.C. (3d) 380 (Ont. C.A.), at para. 29.
 There is no question that the instructions in the present case fulfilled this essential requirement. The trial judge repeatedly made clear to the jury that a guilty verdict can only be rendered if guilt is the sole rational inference to be drawn from the circumstantial evidence. The issue to be resolved, rather, is whether the use of the words “equally rational” and “as reasonable” detracted from the otherwise correct instructions by leading jurors to believe, as the respondents contend, that they could only acquit if they found an innocent inference from the circumstantial evidence of the same weight as an inference of guilt. It is argued that the impugned language had the potential to engage the jury in an abstract comparative exercise, assessing the qualitative reasonableness of one inference against another when the mere existence of any rational, non-guilty inference is sufficient to raise a reasonable doubt.
 Read in context, as all jury instructions must be, it becomes apparent that the words “equally rational” and “as reasonable” were not used as measures of the comparative value or weight of a non-guilty inference, but, as the judge himself explained to counsel, to describe the quality of any inference, guilty or otherwise, which might be drawn from the circumstantial evidence. Indeed, no one argues that the jury should be entitled to base its decision on irrational or unreasonable inferences. When the instructions on circumstantial evidence are read as a whole, it is more likely than not that they would have been understood by the jury in the manner intended by the trial judge. That said, it is my view that the instructions on this point were not as clear as they could have been and, consequently, the trial judge was wise to recharge the jury as he did.