Criminal Law

By Satomi Hamon

27.09.23

‘Not guilty’ because of mental impairment: What is the process and is there a punishment?

A man who was found not guilty of attempted murder due to mental impairment a few years ago has recently engaged in a similar attack at the same location. Commentary on social media regarding the recent attack at the ANU indicates a lack of understanding by the public of what the consequences are for people who are acquitted of serious offences due to mental impairment. The purpose of this blog is to explain the defence of mental impairment, how it is determined in Court and the outcomes that follow.

Defence of mental impairment

Section 28 of the Criminal Code 2002 (ACT) (“the Criminal Code”) provides a defence to a criminal allegation in the following terms:

A person is not criminally responsible for an offence if, when carrying out the conduct required for the offence, the person was suffering from a mental impairment that had the effect that—

  1. The person did not know the nature and quality of the conduct; or
  2. The person did not know that the conduct was wrong; or
  3. The person could not control the conduct.

That section further specifies that “a person does not know that conduct is wrong if the person cannot reason with a moderate degree of sense and composure about whether the conduct, as seen by a reasonable person, is wrong.”

Pursuant to that section, if the Court is satisfied a person is not criminally responsible for an offence because of mental impairment it must find the person not guilty of the offence.

Legal definition of mental impairment

‘mental impairment’ is defined in section 27 of the Criminal Code 2002 (ACT) to include “senility, intellectual disability, mental illness, brain damage and severe personality disorder.”

‘mental illness’ is further defined as ‘an underlying pathological infirmity of the mind, whether of long or short duration and whether permanent or temporary, but does not include a condition (a “reactive condition”) resulting from the reaction of a healthy mind to extraordinary external stimuli.’

How does the Court determine an accused person is not guilty by way of mental impairment?

Every person that comes before the Court is presumed to be of sound mind until proven otherwise. This presumption is displaced if the Court is satisfied to the civil standard (on the balance of probabilities) that the person was suffering from a mental impairment, which had the effect described in section 28 of the Criminal Code.

The Court will usually be presented with evidence from psychiatrists and/or psychologists who have assessed the accused person. Often there are multiple experts who may give competing evidence in relation to the one accused person and the Court must decide which, if any, expert evidence it accepts when making its decision.  

What happens after an accused person is found not guilty because of mental impairment?

If an accused person has been found to have committed the physical elements of an offence but is not guilty based on mental impairment, this does not result in a full acquittal. The matter must then be referred to the ACT Civil and Administrative Tribunal (“the ACAT”) so that the accused can be assessed under the Mental Health Act 2015 (ACT) (“the Mental Health Act”). If the accused person has been acquitted of a serious offence (such as attempted murder) the Court is likely to detain that person for immediate review by the ACAT.

The ACAT may then make a psychiatric treatment order or a community care order in relation to the person.

Psychiatric treatment order

Under section 58 of the Mental Health Act, the ACAT may make a psychiatric treatment order (“PTO”) in relation to a person if:

  1. The person has a mental illness; and
  2. Either cannot, or does not, consent to treatment, care or support; and
  3. The ACAT believes on reasonable ground that, because of the mental illness, the person is:
    1. Doing or is likely to do serious harm to themselves or someone else; or
    1. Suffering, or is likely to suffer, serious mental or physical deterioration.

A PTO often authorises a person’s involuntary treatment in a mental health facility. It may also impose restrictions on their communication with others.

Community care order

Under section 66 of the Mental Health Act, the ACAT may make a community care order (“CCO”) in relation to a person if:

  1. The person has a mental disorder; and
  2. Either cannot, or does not, consent to treatment, care or support; and
  3. Is doing or is likely to do serious harm to themselves or to someone else; or
  4. Is suffering, or is likely to suffer, serious mental or physical deterioration.

A CCO can authorise a person’s involuntary treatment, care and support in a mental health facility or in the community. It can also impose restrictions on their freedom.

There is a consequence – is it a punishment?

Contrary to what appears to be popular public opinion, people who are found not guilty of serious criminal offences due to mental impairment do not just get released back into the community without consequence. These people are not ‘punished’ by the Court, but, in reality, they are often detained for indefinite and prolonged periods which can sometimes result in their freedoms being restricted for a longer time than if they had been convicted.