Background
Callan Davidson was charged with murdering his mother, Cheryl Anne Davidson, at a tourist park in Gunnedah on 25 October 2024. Davidson, who had been living an itinerant life and sleeping in a tent, had displayed paranoia, delusions and other disturbed behaviour for an extended period. His mother had tried to obtain mental-health assistance for him and had arranged an appointment for the afternoon of the killing.
That morning, Davidson bought steak knives and fatally attacked his mother inside his tent, inflicting 106 sharp-force injuries. Police arrested him at the scene. He later told forensic psychiatrists that he had experienced delusions and command hallucinations involving the Freemasons and believed he was required to kill his mother.
Davidson pleaded not guilty, and the matter was to proceed as a judge-alone trial. The prosecution and defence subsequently agreed under s 31 of the Mental Health and Cognitive Impairment Forensic Provisions Act 2020 (NSW) that the proposed evidence established the defence of mental health impairment, leaving the Court to assess the evidence independently.
The Court’s Holding
Campbell J accepted the opinions of two forensic psychiatrists that Davidson had suffered from severe, chronic schizophrenia since at least early 2022 and was experiencing active psychosis at the time of the killing. Although Davidson knew the nature and quality of his actions, the illness, including paranoid delusions and command hallucinations, left him unable to reason with a moderate degree of sense and composure about whether killing his mother was morally wrong.
The Court was satisfied on the balance of probabilities that Davidson had established the mental health impairment defence under s 28 of the Act. It therefore returned the special verdict “act proven but not criminally responsible,” rather than an ordinary acquittal.
Davidson was ordered detained in a correctional facility, or another place determined by the Mental Health Review Tribunal, until released by due process of law. The Court referred him to the Tribunal, which will supervise his detention, care and treatment and may not release him unless the applicable public-safety requirements are met.
Key Takeaways
- A mental-health diagnosis alone does not establish the statutory defence; the impairment must have caused the accused not to know the nature and quality of the act or not to know that it was morally wrong.
- The accused bears the burden of establishing the mental health impairment defence on the balance of probabilities, even when the prosecution agrees that the evidence supports it.
- A special verdict of act proven but not criminally responsible is not an unconditional acquittal and may result in indefinite forensic detention subject to Mental Health Review Tribunal supervision.
Why It Matters
The decision illustrates the Court’s independent role under s 31: agreement between the prosecution and defence does not itself determine the outcome, because the Court must consider the evidence and be satisfied that the statutory defence is established.
It also distinguishes intent from criminal responsibility. A person experiencing schizophrenia may intend the physical consequences of an act yet remain not criminally responsible if the illness prevents the person from understanding the act’s moral wrongness in the statutory sense.