Defence of mental impairment

I want to start this discussion about mental impairment by briefly mentioning something about the history of this concept in the jurisdiction from which I come from, in Victoria in Australia. In April of 1998, the Victorian government (state government), enacted the Crimes, Mental Impairment and Unfitness to be Tried Act, 1997. And the Act pioneered a more humane approach to dealing with mentally ill offenders. It abolished the defense of insanity and it abolished the court’s power to order that a person be detained in strict custody until the Governor’s pleasure was known. Although the Act introduced what it described as the defense of mental impairment, much of its basic workings have its roots in the common law pertaining to the defense of insanity.

So, let’s, with that history or background in mind, turn and ask the question what is mental impairment? The term itself, mental impairment, is not defined in the legislation, but it has been held to have the same meaning as disease of the mind, which forms the basis of the common law insanity defense. Disease of the mind has been held to be synonymous with mental illness. It connotes an unhealthy or infirm mind as opposed to a healthy mind affected by a transient, non recurrent mental malfunction caused by external forces.

Schizophrenia is, for example, a disease of the mind. It is an organic mental illness. Now, a delusional or psychotic state, on the other hand, which is brought on by drug abuse, for example, is not a disease of the mind. Rather, it’s a transient state brought on by the external agency of ingesting drugs. Insanity or mental impairment is only available in cases of a disease of the mind. Now, a person is presumed not to be suffering from a mental impairment until the contrary is proved, and that reflects the common law presumption of sanity. The onus of rebutting the presumption of sanity rests on the party raising the question of mental impairment.

In most cases it will be the defense that raised the issue and who will be required to prove that the accused was mentally impaired. However, the burden will rest on the prosecution if they raise the issue.

And the prosecution can only do so with the judge’s leave. Now, the defense of mental impairment must be proved on the balance of probabilities. That, of course, reflects the standard of proof that existed under the common law. Apart from some limited circumstances in which a judge may determine the issue, determining whether or not an accused suffered from a mental impairment is a question of fact for the jury. When mental impairment is raised as an issue and if a jury finds the accused not guilty, they must specify in their verdict, whether they have done so on the basis of mental impairment. So let’s come to the question, what is the defense of mental impairment?

Essentially, it’s this: that people will have a defense to what would otherwise be a criminal act if at the time they committed the act, they were suffering from a mental impairment that had the effect that they either, did not know the nature and quality of what they were doing or, they did not know that their conduct was wrong.

Now, if the defense of mental impairment is established, then the appropriate verdict will be not guilty because of mental impairment. The effects of such a verdict, specified in the legislation are those, which direct the court to either declare a person liable to supervision under the Act, and that will be judicial supervision, or, alternatively, to order that the person be released unconditionally. Now, coming back to the two limbs of the test that I’ve posited as to mental impairment and the first of them was the nature and quality of the act.

People will have a defense to what would otherwise be a criminal act, as I’ve said, if at the time they committed the act, they were suffering from a mental impairment that had the effect that they did not know the nature and quality of their conduct. And that provision restates one of the limbs of the common law defense of insanity. And in that context, the phrase nature and quality has been held to refer to the physical character and significance of a person’s actions and the consequences of those acts. It does not refer to the moral quality of the person’s conduct.

Now, to satisfy this limb of the defense, the accused must have been unable to appreciate the physical nature of what he or she was doing and the consequences of his or her behaviour. In the case of murder, for example, the accused must have had so little capacity for understanding the nature of life and the destruction of life, that to him or her it was like breaking a twig or destroying an inanimate object. So that’s the first limb. Let’s turn to the second limb that may also establish this defense, and that is knowledge of wrongfulness.

Now, people will have a defense to what would otherwise be a criminal act if at the time they committed the act, they were suffering from a mental impairment that had the effect that they did not know that their conduct was wrong. And let me explain that a bit further. The legislation defines this particular limb as meaning that the person could not reason with a moderate degree of sense and composure about whether the conduct as perceived by reasonable people was wrong. And this principle refers to wrong as meaning contrary to the ordinary principles of reasonable people, rather than contrary to the law or contrary to morality. It essentially restates one of the limits of the common law defense of insanity.

And it’s clear from the definition in the legislation that the prosecution must at least prove, beyond reasonable doubt, that the accused committed the act or omission which constitutes the offense charged. Now, to summarize some of what I’ve been through already, the prosecution must first prove beyond reasonable doubt that the accused engaged in the conduct constituting the offense. And if the jury are not satisfied of that matter, then of course, the accused will be found not guilty irrespective of any mental impairment that they might have. And in those circumstances, the accused would be discharged and free to leave the court just as they had…just as if they had been acquitted in the ordinary way.

If, however, the jury was satisfied beyond reasonable doubt that the accused had engaged in the conduct constituting the offense, they would then go on to examine whether the defense have proven, on the balance of probabilities, that the accused had a mental impairment at the time they committed the acts that constitute the offense; and that the mental impairment affected the accused in such a way that when he or she committed the act seemed to constitute the offense, they either, did not know the nature and quality of what they were doing, or, and this is more commonly the case, that they did not know what they were doing was wrong.

If those requirements are met, the jury may return a verdict of not guilty because of mental impairment. I think it’s worth pointing out that in practice, a jury considering these matters will also be told that if they return a verdict of not guilty by reason of mental impairment, there will be two options open to the judge. The first is to declare the accused liable to a supervision order, which would involve supervision by the court in a mental health facility or in the community. And the second is to order that the accused be released unconditionally. And the judge would need to form a view based on the evidence as to what was the appropriate course to be followed.

So, hopefully that suffices as a summary as to the law relating to mental impairment or insanity. I hope this has been useful. Thank you.