"The question you must answer is whether at the time the accused did the act or acts which caused the death of the deceased - namely, stabbing - the accused has proved on the balance of probability that he was in such a state of mental impairment as to (1) deprive him of the capacity to understand what he was doing, or (2) deprive him of capacity to control his actions, or (3) deprive him of capacity to know that he ought not to do the act or acts.
In other words, when the accused fatally stabbed the deceased was he deprived of any one or other of those capacities? If you are satisfied that it was more probable than not that he was deprived of any one or other of those capacities, you would be entitled to bring in a verdict of not guilty on account of unsoundness of mind. If that is your verdict, you will then be asked to bring in a special verdict stating the offence the person was acquitted of; that is, whether of wilful murder, murder or manslaughter, and that requires you to consider, apart from unsoundness of mind, what your conclusion would otherwise have been.
If you get to that point in relation to the charge of wilful murder, that's the end of your deliberations. However, if you are not satisfied on the balance of probability that the accused was of unsound mind when he stabbed the deceased, you will then have to consider his specific intention at the time he did the act or acts which killed the deceased. If you are satisfied beyond reasonable doubt that the accused killed the deceased intending to kill him, you would be entitled to find him guilty of wilful murder if you were satisfied beyond reasonable doubt that the accused was not acting in self-defence or under provocation.
If you are unable to exclude self-defence beyond a reasonable doubt, the accused would be entitled to a verdict of not guilty. If you are able to exclude self-defence, you would have to consider whether the crown has excluded provocation beyond reasonable doubt. If it had not, the proper verdict would be not guilty of wilful murder but guilty of manslaughter.
If you were not satisfied beyond reasonable doubt that the accused intended to kill the deceased, you would have to consider whether the accused stabbed the deceased with the intention of causing him grievous bodily harm. If you were satisfied that he did so and you were so satisfied beyond reasonable doubt, the proper verdict would be guilty of murder if you were able to exclude self-defence and provocation.
Again, if you were unable to exclude self-defence beyond reasonable doubt, you would have to find the accused not guilty, and if you were able to exclude self-defence but were unable to exclude provocation, you would find the accused not guilty of murder but guilty of manslaughter."