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8.4.1 - Charge: Mental Impairment

Click here to obtain a Word version of this document for adaptation.

 

Warning! The law is currently unclear on when this direction should be given within a charge. See Mental Impairment for guidance on that issue.

 

Introduction

In this case, defence counsel[1] has raised what is called the "defence of mental impairment", submitting that NOA should be found not guilty of [insert name of offence] because s/he was mentally impaired when s/he [insert relevant acts]. I therefore need to give you some directions about this defence.

Onus and Standard of Proof

According to the law, people should not be held criminally responsible for acts they do while suffering particular effects of a mental impairment. So even if the prosecution can prove, beyond reasonable doubt, that NOA [identify matters the prosecution must prove],[2] s/he will not be guilty of [identify offence] if s/he committed those acts while suffering certain mental conditions.

However, in the absence of any evidence to the contrary, the law presumes that people are not mentally impaired. So if you are to find that NOA was not guilty because of a mental impairment, it is the defence who must prove that s/he was mentally impaired at the time s/he [did the acts / made the omissions] said to constitute the crime.

You can see that this is one of those rare situations in which a matter must be proved by the defence. The prosecution must still prove [identify matters the prosecution must prove] before you need to consider the issue of mental impairment. However, if you are satisfied that those matters have all been proven, it is defence counsel who must prove the requirements of this defence if you are to find the accused not guilty because of mental impairment.

Unlike the elements of the offence – which the prosecution must prove beyond reasonable doubt – the defence only needs to prove these requirements on what is called the "balance of probabilities". This is a much lower standard than that required of the prosecution when proving an offence. It only requires the defence to prove that it is more probable than not that NOA was mentally impaired to the necessary degree.

Overview of Requirements

There are two requirements that the defence must prove, on the balance of probabilities, if you are to find the accused not guilty because of mental impairment. I will list them for you, and then explain each one in more detail.

First, the defence must prove that the accused was suffering from a mental impairment at the time that s/he did the acts said to constitute the relevant crime.

Second, the defence must prove that the mental impairment affected the accused in one of two ways. It must have affected the accused in such a way that s/he either did not know the nature and quality of what s/he was doing, or s/he did not know that what s/he was doing was wrong.

If you find that the prosecution has proven, beyond reasonable doubt, that [identify matters the prosecution must prove], and you are also satisfied that both of these requirements have been proven by the defence on the balance of probabilities, then this defence will be successful and you must find NOA not guilty of that offence because of mental impairment.

However, if the defence cannot prove, on the balance of probabilities, both that NOA had a mental impairment at the relevant time, and that the mental impairment affected him/her in one of the two ways I have just mentioned, then this defence will fail. If you are also satisfied that all of the elements of the offence have been proven by the prosecution, beyond reasonable doubt, you should find NOA guilty of [insert offence].

I will now explain each of these requirements in more detail.

Mental Impairment

The first requirement that the defence must prove is that the accused was suffering from a mental impairment at the time that s/he did the acts said to constitute the crime of [insert offence].

The law does not define what "mental impairment" means. It is not a psychiatric term with a specific medical definition. It is a term which simply means a disease or illness of the mind. This includes [insert relevant mental impairments].

[If there is evidence that the accused may have been suffering from a temporary state of mind rather than a mental impairment, add the following shaded section]

To satisfy this requirement, the accused must have been suffering from some kind of mental illness or disorder, and not just from a temporary state of mind such as impulsiveness or passion. This is not to suggest that the mental impairment needs to be permanent – but it must be something more than just a passing mental malfunction.

[If there is evidence that the accused's mental impairment was caused by an external factor, add the following shaded section]

To satisfy this requirement, the mental impairment must have been caused by something "internal" to the accused, as distinct from being the result of an external physical factor, such as [insert relevant example].

In this case, the defence alleged that NOA was suffering from a mental impairment when s/he [insert relevant acts and summary of evidence and/or arguments]. The prosecution denied this, submitting [insert summary of relevant evidence and/or arguments].

It is for you to decide, based on all of the evidence, if NOA was suffering from a mental impairment at the relevant time. It is only if the defence has proved that this was more likely than not that this first requirement will be met.

Effect of the Mental Impairment

The second requirement that the defence must prove relates to the effect of the mental impairment on the accused. The defence must prove that the mental impairment affected him/her to such an extent that when s/he committed the acts said to constitute the crime s/he either:

The defence only needs to prove one of these effects, although in some cases there may be evidence of both. I will look at each of them in turn.

Nature and Quality of the Act

The first way in which the defence can satisfy this requirement is by proving, on the balance of probabilities, that the accused’s mental impairment affected him/her to such an extent that s/he did not know the nature and quality of what s/he was doing.

This means that because of his/her mental impairment, the accused was unable to appreciate the physical nature and significance of what s/he was doing when s/he committed the acts said to constitute the crime. The accused was affected by his/her mental impairment in a way which led him/her to believe s/he was doing one thing, when in reality s/he was doing something completely different.

An example of this would be where a person thinks she is entering her own house, when she is in fact breaking into Parliament House. Another example would be a person who thinks that he is killing a rabbit, when in reality he is killing one of his friends.

[If this limb is in issue, add the following shaded section]

In this case the defence argued that NOA did not know the nature and quality of what s/he was doing when [insert relevant acts and summary of relevant evidence and/or arguments]. The prosecution responded [insert relevant evidence and/or arguments].

[If this limb is not in issue, add the following shaded section]

The defence has not sought to rely on this part of the second requirement, instead alleging that NOA did not know that his/her actions were wrong.

Knowledge that NOA’s actions were wrong

The second way in which the defence can satisfy this requirement is by proving, on the balance of probabilities, that when the accused committed the acts said to constitute the crime, the mental impairment affected him/her to such an extent that s/he did not know that what s/he was doing was wrong.

The law defines this to mean that the accused could not reason with a moderate degree of sense and composure about whether his/her conduct, as perceived by reasonable people, was wrong.

You can see from this definition that the test is not whether the accused’s acts were in fact wrong, or that accused knew that his/her actions were wrong according to the law or morality. It is that the accused was not able to reason in such a way that s/he would have known that reasonable people would consider his/her conduct to be wrong. That is, there was something so wrong with the accused’s mind due to his/her mental impairment that s/he was incapable of realising that reasonable people would think his/her behaviour was wrong.

[If this limb is in issue, add the following shaded section]

In this case the defence argued that NOA did not know that what s/he was doing was wrong when [insert relevant acts and summary of relevant evidence and/or arguments]. The prosecution responded [insert relevant evidence and/or arguments].

[If this limb is not in issue, add the following shaded section]

The defence has not sought to rely on this part of the second requirement, instead alleging that NOA did not know the nature and quality of what s/he was doing.

Summary, Possible Verdicts and Consequences

To summarise, you must first determine whether the prosecution has proven, beyond reasonable doubt, [identify matters the prosecution must prove]. If you are not satisfied that the prosecution has proven all of these matters, then you must find NOA not guilty of that offence, regardless of your views about his/her possible mental impairment. As s/he will not have been convicted of that offence, that will be the end of the legal process. S/he will be discharged and free to walk away from the court.

If you decide that the prosecution has proven all of those matters beyond reasonable doubt, you must then look at the defence of mental impairment. You must determine whether the defence has proven, on the balance of probabilities, that:

It is only if the accused has established both of these requirements on the balance of probabilities that you may return a verdict of "not guilty because of mental impairment".

If that is your verdict, then there will be two options open to me. The first is to declare that the accused is liable to a Supervision Order, and the second is to order that s/he be released unconditionally. I would have to form a view, based on the evidence, as to what was the appropriate course to be followed.

A Supervision Order, which is the first option that would be open to me, may commit the person to custody, or release the person on conditions decided by the court and specified in the Order.

So you can see that there are different legal consequences that follow from the different verdicts available to you. And you can see, as I have told you, that a verdict of not guilty because of mental impairment has quite different consequences from a verdict of not guilty.

Because of these different consequences, it is necessary for you to tell me, if you reach a verdict of not guilty, whether you have reached that verdict because of mental impairment or not.

Although I have just explained to you the possible consequences of the different verdicts available in this case, it is important that you do not take these consequences into account in making your determination. As I told you earlier, you have an obligation to make your decision based on the evidence in the case, not on irrelevant factors such as the consequences of your decision.

 

Notes

[1] This charge is based on the assumption that the defence has raised the issue of mental impairment. If it is the prosecution that has raised the issue, the charge will need to be modified accordingly.

[2] It is unclear precisely which matters the prosecution must prove (see "Mental Impairment and Proof of Elements" in Mental Impairment). The content of this part of the charge, as well as similar sections below, will depend on how the judge resolves these issues.

Last updated: 23 November 2011

See Also

8.4 - Mental Impairment

8.4.2 - Checklist: Mental Impairment