//
© 2026 Zoe. All rights reserved.
Zoe is a legal information platform. Always consult the Federal Register of Legislation for authoritative text.
[2005] VSC 518
Supreme Court of Victoria
2005-06-08
Bongiorno J
Original judgment source is linked above.
Crime - defence of mental impairment - interpretation of "a mental impairment" - Cannabis-induced psychosis not a disease of the mind entitling accused to an acquittal on the grounds of mental impairment - Crimes (Mental Impairment and Unfitness to be Tried) Act 1997.
1 In this case which involves a charge of murder and a number of charges of intentionally endangering life, counsel for the accused, Martin, Mr O'Connell, seeks a ruling that if it can be established on the evidence that his client was suffering from cannabis-induced psychosis at the time of the events giving rise to these charges he should be able to seek a verdict of acquittal on the ground of mental impairment.
2 To achieve this Mr O'Connell must establish that mental impairment within the meaning of the Crimes (Mental Impairment and Unfitness to be Tried) Act 1997 encompasses the condition from which it appears his client may have been suffering at the relevant time. This involves two questions. The first is a question of construction of the Act, that is to say whether mental impairment as a concept is the same or wider than the old common law concept of "disease of the mind", as that phrase is used in the condition precedent to the application of the M'Naghten Rules as to insanity.
3 The second is whether the diagnosis of cannabis-induced psychosis as it has been diagnosed in this case could justify, as a matter of law, a verdict of acquittal on the ground of mental impairment.
The construction question
4 In R v Sebalj [1], Smith, J held that mental impairment means no more and no less than " a disease of the mind" as that concept was used in the common law M'Naghten defence of insanity. Mr O'Connell criticised this view as being unduly restrictive and as failing to give due weight to the fact that the Crimes (Mental Impairment and Unfitness to be Tried) Act 1997 in terms abolished the common law defence of insanity and replaced it with a new concept. This Court should not read the new concept restrictively, argued Mr O'Connell. He said such an interpretation would be incongruous, anomalous and counter intuitive.
5 Given that there is no definition of mental impairment in the Act, the ordinary meaning must be given to the words, "mental impairment", said Mr O'Connell. He referred to dictionary definitions and to the fact that nowhere in the Act is there any warrant for a limited construction, particularly as this legislation is of a criminal or penal nature.
6 Mr O'Connell's submissions echo the criticism of Smith, J's ruling in Sebalj by the Victorian Law Reform Commission in its recent final report on defences to homicide. It said that Smith, J's ruling, and another by Teague, J in R v R [2], runs contrary to the underlying conceptual purpose of the mental impairment defence, that is that people should be excused from criminal responsibility where their cognitive functions are so affected that they are unable to understand what they were doing and/or that it was wrong.
7 The Victorian Law Reform Commission disagrees with Smith, J's construction of the Act, which is of course, the current law of Victoria until it is overruled by the Court of Appeal. The Victorian Law Reform Commission disagrees on the ground that it does not provide a sufficient level of "flexibility" in the application of the defence, although just what this really means is not exactly clear.
8 Smith, J interpreted the Parliamentary intention expressed in the Act by reference to a statement by the Attorney-General in the second reading speech on the Bill. Even if it is necessary to find ambiguity or uncertainty in the terms of a legislative enactment to justify resort to intrinsic materials in aid of interpretation, such ambiguity or uncertainty is raised here by the Act's contemporaneous abolition of the common law defence of insanity with its creation of a new defence of mental impairment without defining that term.
9 The second reading speech, however, dispels the apparent uncertainty by expressly stating that all that was intended by the Act was a change in nomenclature, even if the speech also asserts a clarity in the Act which is patently absent.
10 The term "disease of the mind" has been accepted by the High Court as being synonymous with the term "mental illness", R v Falconer [3], per Mason CJ, Brennan and McHugh JJ, at 53, where their Honours approve a passage from R v Radford [4] where King, CJ expressly accepts that the term, "disease of the mind" is synonymous with mental illness.
11 It might be able to be said that the term "mental impairment" is wider than the term "mental illness" but, having regard to the fact that the High Court was prepared to accept that the latter term was synonymous with disease of the mind, and having regard to the statement of the Attorney-General in the second reading speech to which Smith J referred, it seems to me that, in this instance at least, it was intended that the phrase "mental impairment" be synonymous with the phrase, "disease of the mind".
12 The function of a Court construing a statute is to ascertain the Parliamentary intention by reference to the words used in the statute. It is commanded by statute to prefer a purposive interpretation of those words.[5] It is permitted to consider extrinsic materials. In this case those materials express the purpose of the Act unmistakably. However it went about it, the Parliament intended only that there be a change in nomenclature in that part of the Act dealing with the abolition of the common law defence of insanity. Smith Js interpretation of s.20 of the Act as doing no more than re-enacting the M'Naghten rules in preferred language is, with respect, correct. "Mental impairment" is synonymous with "disease of the mind".
13 The second question is, is cannabis-induced psychosis a disease of the mind? On the voir dire Mr O'Connell called Dr Suresh Sundram, an acknowledged expert psychiatrist, who described the condition of cannabis-induce psychosis. He distinguished it from intoxication, even intoxication by the taking of drugs. He said that intoxication was a predictable and predicted outcome of the ingestion of a particular substance. Its effect is limited by the body's capacity to metabolise that substance such that when such metabolism has taken place the intoxication ceases. Cannabis-induced psychosis, or psychosis induced by drugs in the generic sense, was an additional pathological process, to intoxication said Dr Sundram. It caused symptoms and signs which do not remit. He said that as far as it was understood, the cannabis acted on the brain which resulted in symptoms and signs such as auditory or visual hallucinations, delusional beliefs and possibly impulsive reactions. He added that from the history he obtained from Mr Martin in this case he thought that he was suffering from that disease, or, at least, the symptoms, and signs described by Mr Martin were consistent with it. He likened the disease to delirium tremens with respect to alcohol. This, he said, was a physiological response involving tremors, shakes, sweating and transient psychotic phenomena, which occurred upon the withdrawal of alcohol. It was distinct from intoxication.
14 In cross-examination Dr Sundram conceded that the accused's delusional states were always preceded by the taking of drugs. He said that the quantity of the drug was not critical to the effect, but that if Mr Martin stopped using cannabis there would be no further psychosis. In corroboration of this Dr Sundram said that when he examined Mr Martin he had no psychosis and he had no evidence of any mental disorder. He conceded that it was only by the use of the external substance of cannabis that the psychosis was induced.
15 The question of law which I must answer is whether cannabis-induced psychosis, as described by Dr Sundram and as applying to this accused in this case, is a temporary disorder or disturbance of an otherwise healthy mind caused by external factors such that it cannot be properly regarded as a disease of the mind, as that term is used in the common law.
16 The common law was expressed by the judges in Falconer's case in the same passage where they accepted (with one minor qualification irrelevant for present purposes) the statement of King, CJ's in Radford. Specifically they accepted King, CJ's statement that:
"...I do not think that a temporary disorder or disturbance of an otherwise healthy mind caused by external factors can properly be regarded as disease of the mind as that expression is used in the M'Naghten Rules".[6]
17 Dr Sundram agrees that the accused is not psychotic when he is not taking marijuana and as an example of that he said that at the time he examined him he was showing no psychotic symptoms at all.
18 In the context of this case at least, and on the evidence of Dr Sundram as to this particular accused's condition, although able to be described as a psychosis, Mr Martin's condition falls within the exclusion that King, CJ referred to in Radford and which was accepted by the High Court in Falconer. It was a temporary disorder or disturbance of an otherwise healthy mind caused by external factors, that is to say caused by the ingestion of cannabis and no other cause.
19 This ruling may be affected ultimately by the evidence yet to be given on the trial. Even if I were to rule now that cannabis-induced psychosis, as described in this case, was a disease of the mind for the purposes of the defence of mental impairment, that ruling would be subject to possible revision in light of the facts as they emerge on trial. The ultimate question of law which must be answered will be whether there is any evidence capable of supporting an acquittal by the jury on the ground of mental impairment.
20 Finally, Mr O'Connell made other submissions as to the relevance of Dr Sundram's evidence to the issue of intent. At this stage I will not rule on those submissions for the same reason. There may never be any evidence going to those issues on which Dr Sundram or other psychiatrists could appropriately express opinions. These matters include the question of the possible application of the principle discussed by the Full Court of this Court in R v Voukelatos [7].
21 Accordingly, I rule that the Crimes (Mental Impairment and Unfitness to be Tried) Act 1997 has not, so far as the defence of mental impairment is concerned, altered the common law and that the term mental impairment is synonymous with the term disease of the mind. In this case, on the evidence which I have heard, the condition described by Dr Sundram as cannabis-induced psychosis is not a disease of the mind which would be such as to entitle the accused to an acquittal on the ground of mental impairment. The accused will not be entitled to raise the defence of mental impairment upon his trial.
[3] (1990) 171 C.L.R.30
[4] (1985) 42 S.A.S.R. 266 at 274-275
[5] s.35 Interpretation of Legislation Act 1985.
[6] R v Falconer [1990] HCA 49; (1990) 171 CLR 30 at 53.
R
Martin [2005] VSC 518
(1990) 171 CLR 30