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Supreme Court 19 April 2024

R v Patterson (No 5)

[2024] NSWSC 457

HomicideDrugs
CRIMINAL LAW MURDER EVIDENCE ADMISSIBILITY OBJECTIONS RELEVANCE

Citation: R v Patterson (No 5) [2024] NSWSC 457
Court: Supreme Court of New South Wales
Date: 19 April 2024
Judge: Dhanji J

Background

The accused faced trial for the murder of his sister. The central issue was not whether the accused committed the acts but whether he was criminally responsible for them. The defence raised both a special verdict of act proven but not criminally responsible (under the Mental Health and Cognitive Impairment Forensic Provisions Act 2020 (NSW)) and, in the alternative, the partial defence of substantial impairment (under the Crimes Act 1900 (NSW)).

All three expert witnesses agreed the accused was in a psychotic state at the time of the offence. The dispute between them concerned the nature of that psychosis: the Crown's expert, Professor Greenberg, attributed it to substance-induced psychotic disorder, while the defence experts diagnosed a schizophreniform disorder and schizophrenia respectively. The experts gave evidence concurrently.

Defence counsel raised objections on the voir dire (a preliminary hearing on admissibility, conducted in the absence of the jury) to several aspects of the Crown's proposed expert evidence. This judgment records Dhanji J's rulings on those objections.

  • Whether the accused's own statements to Professor Greenberg about the drug-related cause of his psychosis were relevant under s 56 of the Evidence Act 1995 (NSW), and, if relevant, whether their probative value was outweighed by unfair prejudice under s 137.
  • Whether evidence that the accused said he had not given up drug use because he enjoyed taking drugs was admissible.
  • Whether evidence drawn from a Justice Health nursing note, recording the accused's reported intravenous drug use in custody, was admissible, having regard to its probative value and the danger of unfair prejudice under s 137.

Decision

The accused's statements about the cause of his psychosis (admitted)

Dhanji J admitted the accused's statements to Professor Greenberg in which the accused attributed his psychotic episode to drug use. On the voir dire, Professor Greenberg explained that this evidence formed part of his reasoning: people with schizophrenia tend to have limited insight into their condition, and the accused's statements demonstrated some degree of insight, pointing away from a schizophrenia diagnosis and toward substance-induced psychotic disorder. The judge accepted that evidence forming part of an expert's disclosed reasoning process is relevant, even if the underlying reasoning may be contested or imperfect. The possibility that Professor Ellis might challenge that reasoning did not make the evidence irrelevant; if anything, it underscored its relevance as a point of contention between the experts.

On the question of prejudice, defence counsel submitted the evidence was of low probative value but was unable to identify any specific unfair prejudice. With no unfair prejudice demonstrated, exclusion under s 137 was not warranted, and the evidence was admitted.

The accused's statements about enjoying drug use (not admitted)

No evidence was led on the voir dire to establish the relevance of this evidence to Professor Greenberg's reasoning. Accordingly, the evidence fell outside the scope of the ruling and was not admitted.

The Justice Health custody note recording in-custody drug use (excluded)

The nursing note recorded that the accused stated he had been injecting buprenorphine since his incarceration. Professor Greenberg relied on this to argue that ongoing drug use would have worsened any genuine schizophrenic illness, and that the absence of significant schizophrenic symptoms from approximately eight to nine days after the offence was therefore inconsistent with a schizophrenia diagnosis. Dhanji J accepted this was one thread in the expert's reasoning, but identified two significant problems with the evidence.

First, the note was ambiguous: it could mean drug use since the start of incarceration, or at some point during incarceration. The note was made more than two years into custody, making it impossible to track any such drug use against the accused's symptom history. This substantially undermined its probative value. Second, the evidence carried significant unfair prejudice: an accused who had killed his sister in brutal circumstances and who had linked his conduct to drugs, yet continued using drugs in custody, risked attracting a strongly adverse moral judgment from the jury. Dhanji J found there was a significant danger the evidence would be used in a way that was not logically probative to its stated purpose. Probative value was outweighed by the danger of unfair prejudice, and the evidence was excluded under s 137.

Orders Made

• Evidence tending to show drug use by the accused in custody was ruled inadmissible

Key Takeaways

  • Evidence forming part of an expert's disclosed reasoning process is relevant for the purpose of s 56 of the Evidence Act, even where the reasoning may be open to challenge or characterised as circular; the appropriate response to a contested reasoning chain is cross-examination or competing expert evidence, not exclusion.
  • Under s 137 of the Evidence Act, the party seeking exclusion must point to identifiable unfair prejudice; a submission that evidence has low probative value, standing alone, does not discharge that task.
  • Where a Crown expert relies on material from a business record (here, a justice health nursing note), ambiguity in the underlying document can substantially undermine the probative value of the opinion built upon it, and may tip the balance toward exclusion when weighed against unfair prejudice.
  • Evidence of an accused's post-offence, in-custody conduct is susceptible to exclusion under s 137 where it carries a real risk of generating adverse moral reasoning by the jury that goes beyond its logical relevance to the issues at trial.
  • The competing expert's position can itself reinforce the relevance of disputed evidence: where one expert says a particular matter is irrelevant to diagnosis, that disagreement identifies it as a live issue in the expert contest, lending weight to its relevance in the overall proceedings.

Legislation and Cases Referenced

Legislation

  • Crimes Act 1900 (NSW), s 23A (substantial impairment by abnormality of mind)
  • Evidence Act 1995 (NSW), s 56 (relevant evidence admissible), s 137 (exclusion of prejudicial evidence in criminal proceedings)
  • Mental Health and Cognitive Impairment Forensic Provisions Act 2020 (NSW), s 28 (special verdict of act proven but not criminally responsible)

Cases

No cases were cited in the judgment.