R. v. Pittman, 2011 ONCA 148 deals with, among other things, the "thin skull principle" in criminal law. Put simply, as regards the act, the fact that a victim is peculiarly susceptible to injury is irrelevant. That said, proof of the intent of the accused may affected by peculiar susceptibility. Thus, if an otherwise trivial assault leads to death, the fact the assault is trivial is relevant in determining whether an accused intended to cause death. The Court writes:

[33]         Following that review, the trial judge provided the jury with the following instruction on the thin skull principle:

In this case there is some evidence that the nature and force of the assault by Ford Pittman would not normally have caused death to an average person, but that it caused death to Mary Wood only because Mary Wood's central nervous system was compromised by the drugs she had taken. However, I must tell you that this is not a defence. It is a well-recognized principle in law that Ford Pittman must take his victim the way he finds her. [Emphasis added.]

[34]         The appellant takes issue with that instruction. While he accepts that the thin skull principle is well-recognized, he points out, correctly in my view, that it applies to causation, not intent.

[35]         The appellant submits that the impugned instruction was unnecessary because causation was admitted. Of greater concern, it was prejudicial because it effectively removed from the jury's consideration evidence which supported his position that he did not intend to kill Ms. Wood or cause her serious injury that he knew was likely to result in her death. I agree.

[36]         Put simply, absent evidence that the appellant knew that Ms. Wood was particularly susceptible to being asphyxiated, of which there was none, if a normal person would not likely have been asphyxiated by the degree of force applied by the appellant, that was something the jury could consider in deciding whether the appellant, in using the force he did, either intended to kill Ms. Wood or foresaw the likelihood of her death.