Causation in fact and law

 R. v. Kippax, 2011 ONCA 766 is a helpful case clarifying causation in criminal matters:

[21]         To determine whether a person can be held responsible for causing a particular result, in this case death or bodily harm, we must determine whether the person caused that result not only in fact but also in law: R. v. Nette, 2001 SCC 78, [2001] 3 S.C.R. 488, at para. 44.

[22]         Factual causation involves an inquiry about how the victim died or suffered bodily harm, in a medical, mechanical or physical sense, and an accused's contribution to that result: Nette, at para. 44.

[23]         Factual causation involves a determination of whether A caused B. The answer to the question of whether A caused B is resolved in a criminal case by the evidence of witnesses, those who testify about facts and others who offer relevant opinions: R. v. Smithers, [1978] 1 S.C.R. 506, at 518. The factual determination of whether A caused B has nothing to do with intention, foresight or risk: Smithers, at p. 518.

[24]         To prove factual causation, the Crown does not have prove that an accused's conduct was either the direct or predominant contributing cause of the prohibited consequence, whether death or bodily harm. It is no defence for an accused to say that the conduct of another was a greater or more substantial cause of the death or injuries. The Crown need only prove that an accused's conduct was a significant contributing cause of the death or injuries or, said another way, that the accused's conduct was "at least a contributing cause…outside the de minimis range": Smithers, at p. 519; Nette, at paras. 70-71; and R. v. Hughes, 2011 BCCA 220, 305 B.C.A.C. 112, at paras. 56 and 64.

[25]         Factual causation, as the term itself would indicate, is a question of fact, reviewable only in accordance with a standard of palpable and overriding error: Hughes, at para. 65; and R. v. Shepherd, 2009 SCC 35, [2009] 2 S.C.R. 527, at para. 18.

[26]         Legal causation, on the other hand, has to do with whether an accused should be held responsible in law for a prohibited consequence of his or her conduct, for example, death or bodily harm: Nette, at para. 45. In legal causation, the inquiry is directed at the question of whether an accused should be held criminally responsible for the consequences that occurred: Nette, at para. 45; R. v. Shilon (2006), 240 C.C.C. (3d) 401 (Ont. C.A.), at para. 32. In the analysis of legal causation in negligence-based offences, like dangerous driving, reasonable foreseeability of harm is a relevant consideration: Shilon, at para. 33.

[27]         Conduct that is inherently dangerous and carries with it a reasonably foreseeable risk of immediate and substantial harm satisfies the standard required for legal causation: Shilon, at para. 38. Where the conduct of another is a reasonably foreseeable consequence of the conduct of an accused, the accused may be liable as a principal for the conduct of that other person: Shilon, at para. 54. A person may be liable as a principal if she or he actually does or contributes to the actus reus with the required mens rea: Hughes, at para. 77.

[28]         It is well-established that independent, voluntary human intervention in events started by an accused may break the chain of causation: Shilon, at para. 43. A new event may result in an accused's conduct not being a significant contributing cause of a prohibited consequence. But legal responsibility for an event will remain and the chain of causation will not be broken where an accused intentionally produced the outcome, recklessly brought it about, or if the ordinarily circumspect person would have seen it as a likely consequence of his or her own conduct: R. v. Maybin, 2010 BCCA 527, 263 C.C.C. (3d) 485, at para. 35