Criminal Code Act 1983

(1) If the defence of mental impairment is raised during the trial, the court:

(a) must hear the evidence and representations as to the accused person's mental competence produced by the parties; and

(b) on application by the defence or the prosecution or on its own initiative – may require the accused person to be examined by a psychiatrist or other appropriate expert and the results of the examination to be reported to the court.

(2) After the evidence has concluded and the parties have addressed the jury, the Judge must direct the jury to consider:

(a) the question of mental impairment and determine whether on the balance of probabilities the defence of mental impairment is established; and

(b) whether the evidence establishes the elements of the offence the accused person is charged with, or an offence that the accused person may be found alternatively guilty of, beyond reasonable doubt,

and to determine whether the accused person:

(d) is not guilty of the offence charged because of his or her mental impairment; or

(e) committed the offence charged or an offence that he or she may be found alternatively guilty of.

(3) In directing the jury, the Judge must explain to the jury the findings that it may make and the consequences of the findings in law and otherwise.