Changes to the Defence of Mental Illness (NSW)

The Mental Health and Cognitive Impairment Forensic Provisions Act 2020 (NSW) was assented to in June 2020 and will replace the previous Mental Health (Forensic Provisions) Act 1990 (NSW). Section 38 of the old act currently states that where evidence is given in court which shows that, at the time of the offence, a person was suffering from a mental illness and was not responsible for their actions, the jury must find them ‘not guilty by reason of mental illness’. This is what is known as the defence of mental illness in New South wales.

The definition of ‘mental illness’ which has traditionally been used for the defence of mental illness comes from a very old case called M’Naghten which describes insanity as:

‘A defect of reason, from disease of the mind, as not to know the nature and quality of the act [the defendant] was doing; or, if he did know it, that he did not know he was doing what was wrong.’

The reforms in the new act modify the wording in this provision to a ‘defence of mental health impairment or cognitive impairment.’ The new act introduces a statutory test stating that a person who had a mental health impairment or a cognitive impairment, or both, at the time of carrying out an act that would otherwise amount to an offence will not be criminally responsible if:

‘The impairment had the effect that the person did not know the nature and quality of the act; or that it was wrong because the person could not reason with a moderate degree of sense and composure about whether the act was wrong.’

A special verdict by a jury of ‘act proven but not criminally responsible’ due to mental health impairment or cognitive impairment is now required. The reforms also allow a special verdict to be entered by a court at any time in the proceedings if the defendant and the prosecutor agree.

If you require legal advice or representation in relation to the defence of mental illness or in any other legal matter, please contact Armstrong Legal.