Criminal Code Act 1983

(1) A person (the defendant) who would, apart from this section, be guilty of murder must not be convicted of murder if:

(a) the defendant's mental capacity was substantially impaired at the time of the conduct causing death; and

(b) the impairment arose wholly or partly from an underlying condition; and

(c) the defendant should not, given the extent of the impairment, be convicted of murder.

(2) Expert and other evidence may be admissible to enable or assist the tribunal of fact to determine the extent of the defendant's impairment at the time of the conduct causing death.

(3) If the defendant's impairment is attributable in part to an underlying condition and in part to self-induced intoxication, then, for deciding whether a defence of diminished responsibility has been established, the impairment must be ignored so far as it was attributable to self-induced intoxication.

(4) The burden of establishing a defence of diminished responsibility is a legal burden and lies on the defence.

(5) A defendant who would, apart from this section, be liable to be convicted of murder must be convicted of manslaughter instead.

mental capacity, of a defendant, means the defendant's capacity to:

underlying condition means a pre-existing mental or physiological condition other than of a transitory kind.