Crimes Mental Impairment consultation paper.pdf - Victorian Law ...

Victorian Law Reform Commission
Review of the Crimes (Mental Impairment and Unfitness to be Tried) Act 1997: Consultation Paper
Establishing the defence of mental impairment
5.39 This section will outline how the defence of mental impairment is established. In doing so,
it will consider a number of issues including:
• how ‘disease of the mind’ has been interpreted by the courts in determining criminal
responsibility
• whether ‘mental impairment’ should be defined and if so, how it should be defined
• the application of the defence of mental impairment and the test for determining
whether a person qualifies for the defence.
The meaning of ‘mental impairment’
5.40 The term ‘mental impairment’ is not defined under the CMIA. The terms of reference ask
whether the CMIA should define ‘mental impairment’ and if so, how this term should be
defined.
Current meaning under the CMIA—‘disease of the mind’
5.41 The common law is relied upon in determining what constitutes a mental impairment,
which states that a person must be ‘labouring under such a defect of reason, from
disease of the mind’ 31 in order for the defence of mental impairment to be established.
5.42 A ‘disease of the mind’ has been held to be synonymous with a ‘mental impairment’. 32
5.43 The question of what constitutes a ‘mental impairment’ is a legal rather than medical
one 33 and this legal construct is ‘often difficult to reconcile within medical and public
paradigms of mental illness and justice’. 34
5.44 There has been much debate about which mental conditions constitute a disease of the
mind and it is argued ‘[l]egal definitions of what constitutes a mental condition in the
insanity defence are generally unclear and variable’. 35
5.45 In order for the defence of mental impairment to be established, the actions of the
accused person must be caused by a ‘defect of reason’, that results from ‘an underlying
pathological infirmity of the mind, be it of long or short duration and be it permanent or
temporary, which can be properly termed mental illness, as distinct from the reaction of a
healthy mind to extraordinary external stimuli’. 36
5.46 While mental illness clearly falls within the scope of the defence of mental impairment,
it remains unclear whether other conditions such as cognitive impairment, intellectual
disability, drug induced psychosis or severe personality disorder constitute a mental
impairment.
5.47 A ‘disease of the mind’ does not require a physical deterioration in brain cells or changes
to the structure of fibres and tissues as found in other medical conditions, but it does
require that ‘the functions of the understanding are through some cause, whether
understandable or not, thrown into derangement or disorder’. 37
94
31 Daniel M’Naghten’s Case (1843) 8 ER 718, 722 [210].
32 R v Falconer (1990) 171 CLR 30, 53; R v Radford (1985) 42 SASR 266.
33 R v Radford (1985) 42 SASR 266.
34 Stephen Allnutt, Anthony Samuels and Colman O’Driscoll, ‘The Insanity Defence: From Wild Beasts to M’Naghten’ (2007) 15(4) Australasian
Psychiatry 292, 297.
35 Ibid 295.
36 R v Radford (1985) 42 SASR 266, 274.
37 R v Porter (1933) 55 CLR 182, 189.