To argue for a concept of causality as a mental category for the sake of rendering criminal omissions intelligible is to miss the whole point. (Gimbernat Ordeig was right to oppose an adaequatio theory of truth to this)

It is possible to think of legal norms as rules, that is, expressions of what is regular whithin the field regulated by those norms. We can say that legal norms, apart from their function of regulating behavior, also provide tools for making sense of the world. In this particular sense we may say that omissions have the capacity to be causal. Not by virtue of their exerting effective force of any kind over things, but because there are situations where we actively look to them to provide a causal explanation of the occurence of a certain event. The situation in question is that where a certain rule is infringed, a rule which generally holds that no such thing as the event in question happens, provided that its subjects' conduct is in accordance with the norm. A norm that states that 'one ought to do Y to prevent the result X' can be converted to a rule that states that 'if one does Y, X will, generally, not happen', even if, imho, the process actually happens in reverse, the rule becoming norm. Thus, looking for non-Y in those hypotheses where X happens is descriptive, not normative.