The Defence of Mental Illness in New South Wales

by &
Information on this page was reviewed by a specialist defence lawyer before being published. Click to read more.
Depressed man

Being found not guilty by reason of mental illness isn’t just the stuff of good fiction crime novels, as a recent case in the Supreme Court of New South Wales demonstrates.

In that case, a 38-year old father who stabbed his 5-year old son to death was found not guilty by reason of mental illness.

In delivering judgement, Acting Justice Peter Hidden found that the man, who was diagnosed with schizophrenia in 2003, stabbed his son in the midst of a psychotic episode and didn’t realise that what he was doing was wrong.

The court heard the father stabbed his son 76 times in their Sydney home on a June morning in 2018, after the boy’s mother and grandmother had left the house. The boy had been asleep on a mattress in his parents’ room when his father went into the kitchen, grabbed a knife and unleashed on him.

In the period leading up to the tragic incident, the man was convinced that his son was the devil. Two days prior, the man’s mother and partner attempted to have him admitted to hospital, but were told there were no beds available.

When police arrived after the tragedy, the father told them: “I just murdered my son. I feel sick. I thought my son was the devil. Well I know he is, but he’s dead now, at least I think he is dead.” He added, “The child was trying to tear my soul apart … I knew it was the right thing to do but I didn’t know how much time we had until doomsday.”

In reaching his verdict of not guilty by reason of mental illness, Acting Justice Hidden noted that the man’s condition was well known to his family and mental health professionals.

The reports of two respected forensic psychiatrists were tendered to the court, with one opining that the man had been acting under a “delusional belief” his son was the devil.

The judge found the reports to be persuasive, and was ultimately satisfied that a defence of “not guilty by reason of mental illness” had been established.

The father will remain in a mental health facility indefinitely as a result.

The defence of mental illness

Part 4 of the Mental Health (Forensic Provisions) Act 1990 (NSW) legislates the ‘defence of mental illness’.

The Part was developed from a line of authorities which have their origins in the case of M’Naghten, known as the M’Naghten Rules or M’Naughten Rules.

Section 38 of the Act provides that:

  • If, in an indictment or information, an act or omission is charged against a person as an offence and it is given in evidence on the trial of the person for the offence that the person was mentally ill, so as not to be responsible, according to law, for his or her action at the time when the act was done or omission made, then, if it appears to the jury before which the person is tried that the person did the act or made the omission charged, but was mentally ill at the time when the person did or made the same, the jury must return a special verdict that the accused person is not guilty by reason of mental illness.
  • If a special verdict of not guilty by reason of mental illness is returned at the trial of a person for an offence, the Court may remand the person in custody until the making of an order under section 39 in respect of the person.

In the case of a judge-alone trial, the judge is considered to be the jury for the purposes of the section.

Section 39(1) of the Act states that where such a verdict is returned, ‘the Court may order that the person be detained in such place and in such manner as the Court thinks fit until released by due process of law or may make such other order (including an order releasing the person from custody, either unconditionally or subject to conditions) as the Court considers appropriate.

Section 39(2) makes clear that, ‘[t]he Court is not to make an order under this section for the release of a person from custody unless it is satisfied, on the balance of probabilities, that the safety of the person or any member of the public will not be seriously endangered by the person’s release.’

This means a person in respect of whom a special verdict is returned must be held in a mental health institution indefinitely, until and unless the Mental Health Review Tribunal makes a finding that it is safe to release them – and is a reason that defendants may be reluctant to rely on the defence of mental illness.

Where a jury is involved, section 37 provides that a judge must explain the nature and effect of a special verdict – including the requirement that they will be detained until and unless they are deemed safe to release.

What about local court proceedings?

While Justice Hidden’s decision relates to the extremely serious charge of murder, there are provisions that can assist those suffering from mental health issues who are being dealt with in the local court.

The most frequently used of these is section 32 of the Mental Health (Forensic Provisions) Act 1990 (NSW), which can lead to a person who is suffering from a ‘mental condition’ bypassing the criminal court system by entering a court-mandated treatment plan.

Mental conditions can include things like depression, anxiety, acute substance dependency or more severe conditions such as bipolar disorder, anti-social personality disorder and schizophrenia.

To be successful, a defendant will need to prove to the court that he or she is suffering from a mental condition and, all factors considered, it is in the public’s interest to deal with them by way of a treatment plan than regular court proceedings.

What happens if a section 32 application is successful?

Where a section 32 application is successful, the magistrate will be able to discharge the defendant on the condition that he or she completes a ‘treatment plan’, which can last up to 6 months.

Alternatively, the magistrate can adjourn the case for a period of time to see how the defendant responds to treatment.

If the person is in custody, the magistrate can grant bail on condition that treatment is sought.

The treatment plan will be tailored to the needs of the particular person, and frequently includes:

  1. Attending a treating psychologist on a regular basis,
  2. Taking prescribed medication, and
  3. Having the treatment reviewed.

A person who fails to comply with the plan can be brought back to court and dealt with in the regular manner.

Last updated on

Receive all of our articles weekly


Sonia Hickey

Sonia Hickey is a freelance writer, magazine journalist, and owner of 'Woman with Words'. She has a strong interest in social justice and is a member of the Sydney Criminal Lawyers® content team. Sonia is the winner of the Mondaq Thought Leadership Awards, Spring 2022.
Ugur Nedim

Ugur Nedim

Ugur Nedim is an Accredited Criminal Law Specialist with 25 years of experience as a Criminal Defence Lawyer. He is the Principal of Sydney Criminal Lawyers®.

Your Opinion Matters