1Under s 28(1)(c) of the Criminal Code 2002 (ACT) and s 7.3(1)(c) of the Criminal Code Act 1995 (Cth), the volitional limb of the mental impairment defence requires proof on the balance of probabilities that the accused was entirely unable to control the conduct; a substantially impaired or reduced capacity to control conduct does not suffice.
2The effect of a mental impairment must be assessed separately for each count by reference to the accused's mental state at the time of each offence; an established chronic mental impairment does not automatically displace the presumption of criminal responsibility for all conduct engaged in by the accused.
3Where an accused's explanation for offending conduct is 'reality based' — responsive to actual events and not driven by delusions or psychotic symptoms operative at the time — the defence of mental impairment may not be established even where the accused has a diagnosed chronic mental illness such as schizophrenia or severe borderline personality disorder.
