Mental malfunction is defined to include mental illness, intellectual disability, brain damage, senile dementia, automatism, and gross intoxication. The Australian criminal justice system makes special provision for people with mental malfunctions in various ways. A mental malfunction may be so great that a person is unable to follow court proceedings or give proper instructions to the lawyer. In this case, the individual is unfit to stand trial and is held at the Governor's pleasure until he or she becomes fit to stand trial or charges are withdrawn. A person who is fit to stand trial may have been suffering from a mental malfunction at the time of the alleged offense. Where a mental malfunction prevents an individual from forming criminal intent or knowing that his or her action was wrong, that person should be found not guilty by reason of insanity. With the exception of infanticide, the law does not provide any special defense for a person whose mental condition is not severe enough to justify the insanity defense. Such people are found guilty just as if they were fully responsible. Infanticide is the killing of a baby by its mother when her mind is disturbed by the effects of birth. In this case, the law allows for a verdict of infanticide rather than murder or manslaughter. In rare cases, a person's mental malfunction is so severe as to render the individual equivalent of a robot. Sleepwalking is the most common example of this condition which is referred to in the law as automatism. A successful plea of automatism results in complete acquittal; in contract, an insanity verdict results in indefinite detention. Additional information on consequences of the insanity verdict and unfitness to stand trial is appended. 7 tables and 17 figures