Lamer CJC explained that there is a presumption of criminal capacity. For a minor child, the reverse is true. For a child over age 14, the presumption of incapacity is rebuttable. A claim of insanity undermines the "voluntariness" of either the actus reus or the "mens rea". It can also provide an excuse to criminal conduct, where intention is present. The defence can be raised in a number of ways, therefore. For example, the defence can plead insanity to show a lack of capacity to understand right and wrong, or to show a cognitive breakdown leading to an irresistible impulse to act.