The cases in Victoria which have applied proposition 1 of Verdins have, on the whole, taken the view that a causal connection needs to be established between the impairment of mental functioning and the offending for which sentence is to be imposed. As Maxwell P said in Carroll v R:
Where reliance is placed on [Verdins] proposition 1, concerning moral culpability, the question for the Court is whether the evidence establishes - on the balance of probabilities - that the impairment of mental functioning did contribute to the offending in such a way as to render the offender less blameworthy for the offending than he/she would otherwise have been. Very often, this question is approached as one of causation. Did the evidence establish a causal connection between the impairment of mental functioning and the offending for which sentence is to be imposed?
But nothing in Verdins suggested that the only way to establish a basis for a submission about reduced moral culpability was to show a causal connection. The case law shows that - for what, in our view, are quite understandable reasons - sentencing judges look for some kind of causal link in order to reduce the moral responsibility which is otherwise to be properly to be laid at the feet of the offender.
The court in Verdins identified a variety of ways in which courts had held that impaired mental functioning might reduce moral culpability, as follows:11
Impaired mental functioning at the time of the offending may reduce the offender's moral culpability if it had the effect of -
(a) impairing the offender's ability to exercise appropriate judgment;
(b) impairing the offender's ability to make calm and rational choices, or to think clearly;
(c) making the offender disinhibited;
(d) impairing the offender's ability to appreciate the wrongfulness of the conduct;
(e) obscuring the intent to commit the offence; or
(f) contributing (causally) to the commission of the offence.
As the court there said, this was a descriptive rather than a prescriptive list. It was expressly said not to be exhaustive. Only one of the items in that list - item (f) - referred to causal connection. In short, counsel making submissions on the basis of Verdins has always been in a position to contend that it is not necessary to establish a causal connection.