Citation: R v Patterson (No 6) [2024] NSWSC 458
Court: Supreme Court of New South Wales
Date: 22 April 2024
Judge(s): Dhanji J
Background
The accused stood trial for the murder of his sister. He did not dispute that he carried out the act causing her death, nor that he acted with the relevant intention. His defence was that the appropriate verdict was "act proven but not criminally responsible" under s 28 of the Mental Health and Cognitive Impairment Forensic Provisions Act 2020 (NSW), on the basis that he was suffering a mental health impairment at the time.
Three psychiatrists gave expert evidence: Professor David Greenberg for the Crown, and Doctors Andrew Ellis and Anna Farrar for the accused. While the experts differed on diagnosis, they agreed on several critical points. All three concluded that the accused was experiencing a psychotic episode at the time of the killing, and all three agreed that his impairment was not caused solely by the temporary effect of ingesting a substance or by a substance use disorder.
The Crown nevertheless submitted that the jury could return a guilty verdict, arguing that jurors could form their own view that drug use was the sole cause of the psychosis. This judgment records the ruling Dhanji J made on that submission and the direction given to the jury.
Legal Issues
- Whether the accused satisfied the definition of "mental health impairment" under s 4 of the Mental Health and Cognitive Impairment Forensic Provisions Act 2020 (NSW), specifically whether his impairment was caused solely by the temporary effect of ingesting a substance or by a substance use disorder (s 4(3))
- Whether the Crown bore the onus of establishing on the balance of probabilities that the impairment fell within the s 4(3) exclusions, and if so, whether there was any evidence capable of supporting that conclusion
- Whether the jury could rationally reject unanimous expert opinion where no other evidence contradicted it, and what direction the judge should accordingly give
Decision
Dhanji J accepted the framework endorsed in R v Miller [2022] NSWSC 802 and R v Sheridan [2022] NSWSC 1669: once the accused establishes the elements of mental health impairment under s 4(1), the Crown bears the onus of proving on the balance of probabilities that the impairment was caused solely by the temporary effect of ingesting a substance or by a substance use disorder. The test is not a "but for" test. Establishing that drugs contributed to the psychosis does not satisfy s 4(3); the Crown must show drugs were the sole cause.
All three psychiatrists, including the Crown's own expert Professor Greenberg, expressed the unequivocal opinion that the accused's impairment was not caused solely by the temporary effect of ingesting a substance or a substance use disorder. The experts acknowledged the difficulty of distinguishing between drug-induced psychosis and conditions such as schizophrenia, noting that misdiagnosis of drug-induced psychosis occurs in approximately 25 per cent of cases. Even so, none offered an opinion supporting the Crown's position on sole causation.
The Crown sought to sever Professor Greenberg's opinion: accepting his diagnosis of drug-induced psychosis as a cause of the psychosis, while inviting the jury to disregard his further opinion that drugs were not the only cause. Dhanji J rejected this approach. The Crown could not point to any evidence, from any source, that drugs were the sole cause. The jury's function is to act on the evidence, not to reach a conclusion for which no evidentiary basis exists.
Drawing on well-established authority, including R v Hall (1988) and Hone v Western Australia (2007), Dhanji J concluded that where expert evidence is all one way and there is nothing to throw doubt on it, a verdict contrary to that evidence would not be a true verdict in accordance with the evidence. Accordingly, his Honour directed the jury that the only rational application of the evidence to the law was a verdict of act proven but not criminally responsible.
Orders Made
No orders were made in this decision.
Key Takeaways
- Under s 4(3) of the Mental Health and Cognitive Impairment Forensic Provisions Act 2020 (NSW), the Crown bears the onus of proving on the balance of probabilities that a mental health impairment was caused solely by the temporary effect of ingesting a substance or by a substance use disorder. The section does not operate as a "but for" test.
- Where expert evidence on a mental health impairment defence is unanimous and no other material casts doubt on it, a jury is not entitled to reach a verdict contrary to that evidence merely because, as a general principle, juries are not bound by expert opinion.
- A Crown strategy of accepting part of an expert's opinion (the diagnosis) while asking the jury to reject the expert's related conclusion (on sole causation) will not succeed where there is no independent evidence capable of supporting the rejected conclusion.
- The Supreme Court confirmed that it may direct a jury, in unambiguous terms, that the only rational application of the evidence to the relevant law points to a particular verdict, provided that direction does not remove the ultimate question from the jury.
- Distinguishing between drug-induced psychosis and conditions such as schizophrenia or schizophreniform disorder presents genuine clinical difficulty, with misdiagnosis rates of approximately 25 per cent noted in the evidence. This diagnostic complexity does not, of itself, provide a basis for rejecting unanimous expert opinion on the question of sole causation.
Legislation and Cases Referenced
Legislation
- Mental Health and Cognitive Impairment Forensic Provisions Act 2020 (NSW), ss 4, 28
Cases
- Hone v Western Australia (2007) 179 A Crim R 138
- R v Hall (1988) 36 A Crim R 368
- R v Klamo (2008) 184 A Crim R 262
- R v Miller [2022] NSWSC 802
- R v Sheridan [2022] NSWSC 1669
- Reberger v R [2011] NSWCCA 132
- Ukropina v R [2016] NSWCCA 277