Insanity is a defence raised in any criminal offence which focuses not on the state of mind of the offender per se but on his state of mind at the time of the commission of the offence.
In each jurisdiction in Australia, they have the provisions in their statutes which pertain to the commission of an offence by insane people. The jury has the burden to determine whether the facts prove that the person is suffering from insanity at the time of the commission of the offence. The insane person will not be tried and the court will have to issue an order for detention of that person in the appropriate institution until he is fit to stand trial.
The return of verdict stating that the person is not guilty on the ground of mental illness or insanity is proper only when: the prosecution has proven the offence beyond reasonable doubt independently of the evidence concerning the issue of insanity and on the balance of the probabilities, the defendant has proven his insanity.
When the accused pleaded a defence of insanity, the burden of proof shifted to him as an exception to the general rule that the prosecution has the burden of proving the elements of guilt beyond reasonable doubt. In such a case, what the prosecution must rely on is the presumption that every person is sane and the standard of proof is only a balance of probabilities which the accused has the burden of proving.
In returning a verdict, the jury must first be satisfied that the prosecution has proven the elements of the offence apart from the evidence of insanity. When this is satisfied, it must determine whether the accused is guilty beyond reasonable doubt of the offence charged based on the balance of the probabilities.
Disclaimer : This article is just a summary of the subject matter being discussed and should not be regarded as a comprehensive legal advice for you to defend yourself alone. If you are charged with criminal offences, it is recommended that you seek legal assistance from criminal lawyers.