Mental disorder is relevant to criminal liability in a variety of different ways, and this is true, at least, in all common-law jurisdictions. (25 First, the presence of a mental disorder may be a reason to convince the decider of the fact that, contrary to external appearances, the defendant did not have the mental element for the crime with which he or she has been charged. Lack of the mental element is, of course, a complete defence. Whilst there is not a mental element requirement for all crimes (since there are some crimes for which conviction is based on strict liability), most serious crimes require a mental element that takes the form of intention, recklessness, knowledge, or belief and demand a consideration of what was the individual's purpose, awareness, foresight, or realization at the time that the crime was committed.
Second, the presence of a mental disorder may give rise to a defence. This will arise either by it being raised by the defence (even if the defence does not have the formal burden to prove it, but will have the burden of raising the matter for consideration) or by the prosecution challenging a point made by the defence (so, for example, if the defence raises mental disorder as an explanation for lack of criminal intent, the prosecution may respond by arguing that the defence has, in fact, raised one of the defences concerned with mental disorder). The most obvious defence is that of insanity. Whilst this takes various forms in many jurisdictions, there is usually a relationship in common-law jurisdictions with the English defence that was established by judicial answers to questions posed in McNaghten's case in 1843.(25) This defence demands that the following matters be established by the defence (this is one of those rare instances in which the burden of proof lies, on a balance of probabilities, on the defence).
The defendant must have a disease of the mind. There are at least two possible ways of approaching this concept. First, it may be regarded as a simple concept in that it is present if the defendant has a condition (loosely termed) that has an internal cause, whereas there is no disease of the mind if there is an external cause. This simplistic distinction means that a person who has a brain tumour has a disease of the mind as does a person who has arteriosclerosis, schizophrenia (or other mental illness), epilepsy, diabetes (provided the defendant had not taken her or his insulin and caused the offence in a hypoglycaemic state, or is a sleepwalker). The person with diabetes who causes the offence after taking insulin (an external agent) but falls into a hypoglycaemic state does not have a disease of the mind because the cause (insulin) is external and not internal. Immediately it can be seen that there is no congruence between the legal construct of disease of the mind and any medical approach. Furthermore, this definition of disease of the mind produces outcomes that are clearly unacceptable (no one would argue that many of the conditions identified above are identifiable with mental disorders). An alternative definition, which may reduce some of the impact of the concept is to follow Lord Denning:(26) 'it seems to me that any mental disorder which has manifested itself in violence and is prone to recur is a disease of the mind. At any rate it is the sort of disease for which a person should be detained in hospital rather than be given an unqualified acquittal'.
One difficult area of applying the external/internal causes distinction is in relation to 'whether a "dissociative state" resulting from a "psychological blow" amounts to insane automatism'.(2Z> This was recognized by the Supreme Court of Canada(28) so that the psychological blow can be recognized as an external cause giving rise not to insanity but to automatism as a defence.
The disease of the mind must cause a defect of reason. Defect of reason means that 'the powers of reasoning must be impaired and that a mere failure to use powers of reasoning which one has is not within the [McNaghten] Rules'.(27)
The consequences of actions A and B must be that the defendant either does not know what he is doing or does not know that what he is doing is legally wrong. The latter is contentious, because the Rules simply state that the defendant must know that what he was doing was wrong. In R v. Windle(29> it was the Court of Appeal that established that the requirement was that the matter is concerned with legal wrong. The High Court of Australia has refused to follow this approach. In Stapleton v. R,(30,) 'their view was that if D believed his act to be right according to the ordinary standard of reasonable men he was entitled to be acquitted even if he knew it to be legally wrong'.(27)
The outcome of a finding of insanity is that the defendant is found not guilty by reason of insanity and, since the amendments introduced by the Criminal Procedure (Insanity and Fitness to Plead) Act 1991, the disposal of the defendant is not limited to being sent to a mental hospital under the equivalent of a restriction direction, but extends to less draconian forms of disposal, including discharge.
Third, there are limited or partial defences. In English law there is a defence of diminished responsibility that is a defence only to murder and produces, if successfully raised by the defendant, a conviction for manslaughter. There are similar defences, often of more general application in most, if not all, common-law countries. The defence of diminished responsibility was created by the Homicide Act 1957, Section 2, which provides:
Where a person kills or is a party to the killing of another, he shall not be convicted of murder if he was suffering from such abnormality of mind (whether arising from a condition of arrested or retarded development of mind or any inherent causes or induced by disease or injury) as substantially impaired his mental responsibility for his acts and omissions in doing or being a party to the killing.
The question of impairment of responsibility is one for the decider of fact to make. Interestingly, expert evidence usually contains an assessment of the degree of impairment, though this would appear not to be a matter upon which the expert has the relevant training or expertise. Were the expert witness not to proffer a view on the matter, the practical reality is that the court would find it very difficult to know how to react to a claimed defence. The original rationale for this partial defence was to avoid the rigour of capital punishment. Its current rationale is wide ranging. Amongst other reasons why this defence is important is that it allows the defendant to argue that he or she was incapable of resisting an impulse produced by mental disorder, an argument that is not permissible in the insanity defence as is made clear by the McNaghten Rules themselves.
Fourth, there are other defences which are or may be related to mental disorder. One obvious defence is that of intoxication. If a person is intoxicated by drink or drugs such that he or she does not have the criminal intent for an offence, he or she is not guilty of that offence provided the offence is one of specific intent (such as murder), whereas he or she will be guilty if the crime is one of basic intent (such as manslaughter). Although a range of theories have been propounded to establish when a crime is one of specific or basic intent, the only approach that actually works is to take previous decisions as precedents for future approaches, and so develop a list of crimes of specific and of basic intent.
Was this article helpful?
Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...