Murder

The crime of murder ‘is committed where a person of sound mind and discretion unlawfully kills any reasonable creature in being and under the Queen's peace with intent to kill or cause grievous bodily harm’ (Reference ArchboldArchbold 2015: 19-1). However, if the accused suffered diminished responsibility or a loss of self-control, the offence is reduced to manslaughter. Whereas a murder conviction attracts a mandatory life sentence, the sentence for manslaughter is at the judge's discretion. For diminished responsibility, it is for the defence to raise the issue on the factual evidence and make the case on the balance of probabilities (‘more likely than not’). In relation to loss of control, if the judge decides there is sufficient evidence that there might have been loss of control, it is for the prosecution to disprove loss of control beyond any reasonable doubt.

Diminished responsibility

Diminished responsibility was introduced into English law by the Homicide Act 1957, although the doctrine had been known in the Scottish courts since the 19th century, if not earlier, and the term was first used in 1939 ( Kirkwood v HM Advocate 1939). However, the 1957 definition (which we will call the ‘old DR’) (Box 1) came to be considered outdated in light of developments in psychiatric practice (Law Commission 2004, 2006). In particular, the term ‘abnormality of mind’ and the specified causes in parentheses were considered not to reflect medical understanding of psychiatric disorder. Moreover, for the defence to succeed, the Act required that the effect of the abnormality of mind was to substantially impair mental responsibility. The concept of responsibility, which has a moral element, is not amenable to evidence-based testing within the psychiatric method. Therefore, the specific issue of whether an individual's mental responsibility is impaired should remain a matter for the court rather than the psychiatrist.

A new definition to replace section 2 of the Homicide Act 1957 was introduced by the Coroners and Justice Act 2009 (the ‘new DR’) (Box 1). ‘Abnormality of mental functioning’, which engenders notions of internal processes and faculties, replaces the previous term ‘abnormality of mind’. The legal definition of abnormality of mind (Box 2) remains relevant as ‘things’ listed in the ‘new DR’ (Box 3) can be traced to this judgment. Within the ‘new DR’, there is no longer a concern with specific aetiological categories. The requirement of this defence, that the abnormality of mental functioning arose from a ‘recognised medical condition’, makes the need to refer to accepted diagnostic conventions (most notably DSM-5 and ICD-10) more explicit.

The effect of the abnormality must be to substantially impair one of three defined specific abilities (rather than the defendant's mental responsibility) (Box 3). Abnormal mental functioning provides an explanation for the defendant's involvement in the killing if it causes or is a significant contributory factor in causing the defendant's behaviour (Box 3), rather than, as previously, the defendant's mental responsibility.

These provisions came into effect on 4 October 2010 and only apply to acts or omissions that occurred on or after that date. If the killing occurred before that date, then the unamended provisions of section 2 of the Homicide Act will continue to apply.

Provocation and loss of control

The forerunner of loss of control was provocation, which was codified by section 3 of the Homicide Act 1957 (Box 4). This defence, which was a mixture of common law and statute, was not based on a clear rationale, and ambiguity arose from differing judicial interpretations (Law Commission 2004, 2006). The Coroners and Justice Act 2009 abolished the common law defence of provocation and repealed section 3 of the Homicide Act 1957. In its place, the Coroners and Justice Act introduced a new defence to murder, i.e. loss of control (Box 4).

The first element of this defence is whether the defendant's acts at the time of the incident were a result of their ‘loss of self-control’. In contrast to the former defence of provocation, the Coroners and Justice Act removes the requirement that the loss of self-control was sudden (section 54(2), Box 5). This introduces the potential for the plea to be advanced where there has been a ‘cumulative impact’ of the provocation over a period of time, which may be the case in domestic violence. The second element is that there was a qualifying trigger for the loss of self-control, which is specified as the defendant's fear of serious violence or a justifiable sense of being seriously wronged due to extremely grave words or actions (section 55(4), Box 5). However, the defence is not available if the defendant incited the provoking words or actions to create an excuse for the violence (section 55(6), Box 5). The third element of the loss of control defence is whether a hypothetical individual of the same age and gender as the defendant, with an ordinary level of tolerance and self-restraint might, in the circumstances of the defendant, have reacted in the same way. Circumstances that are relevant only because they have a bearing on tolerance and self-restraint are excluded (section 54(3), Box 5). The plea is not available to defendants who killed in an act of revenge (section 54(3), Box 5).

The psychiatric examination and opinion

The psychiatrist assessing a defendant in a case where diminished responsibility has been raised should consider four questions (Box 6).

First, the psychiatric assessment should inform an opinion on whether the defendant was suffering from a psychiatric disorder at the time of the killing. The introduction of the phrase ‘recognised medical condition’ requires the psychiatrist to adhere to ‘recognised’ approaches to diagnosis. This is likely to mean making reference to either ICD or DSM. However, there may be circumstances in which it is appropriate to refer to some other recognised or authoritative approach to psychiatric diagnosis or the classification of psychiatric disorder.

Second, diminished responsibility requires that there was an ‘abnormality of mental functioning’ arising from the ‘recognised medical condition’. Until ‘abnormality of mental functioning’ acquires a judicial definition, interpretation of the term is likely to be influenced by the ‘abnormality of mind’ test as set out in R v Byrne [1960] (Box 2). However, it is not a term that has an agreed meaning within psychiatric practice. As highlighted above, experts should confine their opinions to their area of expertise, and therefore caution should be exercised in offering evidence on the presence of an issue for which there is not an agreed clinical definition. A widely used clinical construct that refers to mental functioning at a particular time is ‘mental state’. Therefore, in examining, and offering an opinion on, whether the defendant's state of mind was disturbed, and whether this disturbance would be considered by a jury to amount to an abnormality of mental functioning according to the Coroners and Justice Act 2009, the psychiatrist may adopt the conventions of mental state examination and mental state abnormalities. Thus, if the psychiatric evidence indicates that the defendant has a verified diagnosis of schizophrenia, but there was no appreciable mental state disturbance due to the schizophrenia at the time of the incident, then this is unlikely to support diminished responsibility.

Third, the definition of diminished responsibility additionally requires examination of the effect of any identified abnormality of mental functioning (arising from a recognised medical condition) on the three specified mental processes. These are to understand the nature of the defendant's conduct, to form a rational judgement and to exercise self-control, and they are examined further in the next section.

Fourth, whether the abnormality ‘provides an explanation’ for the defendant's involvement in the killing (i.e. it causes or is a significant contributory factor in causing the defendant to display that conduct) needs to be considered. Thus, the psychiatrist should explore and, if possible, offer an opinion on, the connection between the mental state abnormality and the defendant's behaviour at the time of the killing.

In framing their opinion, the psychiatrist needs to remember that the questions posed by this partial defence are matters of fact that are entirely within the jury's province. Psychiatric evidence may be influential, but it is not determinative.

Specified mental processes

The psychiatrist's expert opinion on whether there is substantial impairment of one of the mental processes should be informed by an understanding of the relevant psychiatric evidence base. Although there is not a coherent body of evidence for each of the processes, it is possible to consider whether any identified mental state abnormalities are recognised to cause impairment in one or more of the processes. There is a tension for the psychiatric expert. On the one hand, the psychiatric expert should not generate their own interpretation of a term. On the other hand, the psychiatrist has to come to a view about the meaning of the term to be able to assist the court in addressing whether there is impairment. Case law, arising from the testing of decisions made in courts where the case is first heard (‘courts of first instance’) in higher courts through the appeal process, is often a useful resource to inform the expert's understanding of legal terms. While this resource is available for more mature defences, such as insanity or the ‘old DR’, there has so far been no need for the Court of Appeal to conduct legal analysis of the terms used in the ‘new DR’.

The similarities between the wording of section 52(1A) of the Coroners and Justice Act 2009 (Box 3) and the first limb of the M'Naghten rules have been noted (Mackay 2010). However, whereas for insanity it must be clearly proven that the defendant ‘did not know the nature and quality of the act he was doing’, the Coroners and Justice Act appears to set a lower threshold by reference to impairment as opposed to the absence of understanding. A distinction may also be made between the mental processes suggested by the wording (‘know’ versus ‘understand’) of the respective defences. ‘To know’ means to be aware, and it is not difficult to imagine mental state abnormalities that may result in the individual not being aware of the nature or quality of what they were doing. ‘To understand’ suggests interpretation or perception of meaning. The concept of interpreting or perceiving the meaning of one's own behaviour is not an easy one to grasp. However, the psychiatrist's examination, and opinion, should focus on the individual's thoughts about what they were doing and about the consequences of their actions and how any mental state abnormality may have influenced their train of thinking. In exploring the notion of the person's ability ‘to understand the nature of [their] conduct’, the Law Commission presented the hypothetical case of a 10-year-old boy who had played violent video games excessively and did not have an understanding that a person whom they killed could not be revived in the way that occurred in the games (Law Commission 2006). This is an example of a serious impairment in the individual's capacity to understand the consequences of their actions arising from a distorted view about the effects of violent attack.

Three examples of substantial impairment of the capacity to ‘form rational judgement’ are presented in the Law Commission report (Law Commission 2006). First, a woman suffering from post-traumatic stress disorder due to her husband's violent abuse comes to believe that she can only rid the world of his sins by burning him to death. Second, a depressed man who kills his wife at her request says that he had found it increasingly difficult to stop her requests dominating his thoughts to the exclusion of all else and he thought he would never think straight again until he had acceded to her request. These examples illustrate how the irrational judgement may be the motivating factor for a killing. Third, a ‘mentally sub-normal’ boy who takes part in a killing under his brother's instructions discloses that he would not dream of disobeying his brother and cannot contemplate that his brother would tell him to do something if it was really wrong, even if it involves killing. In this case, it would appear that the irrational judgement (about right and wrong) arises as a consequence of a vulnerability to the malign influence of a dominant figure.

The Law Commission's example of substantial impairment of the capacity to ‘control him or herself’ seems to include irrational judgement as well as impaired self-control (Law Commission 2006). This is the case of a man who says that sometimes the devil takes control of him and implants in him a desire to kill that must be acted upon before the devil will go away.

The phrase ‘substantially impaired’, which has been retained in the ‘new DR’, has been subjected to legal analysis. It was held in R v Golds [2014], if clarification of the term ‘substantial’ is necessary, then the jury should be advised that if they consider that the impairment did not make any great difference, they would find the defendant guilty of murder (Box 7). In order to assist the court to address whether the abnormality of mental functioning substantially impaired one or more of the three mental abilities, the psychiatrist should endeavour to quantify the effect of the mental state disturbance, although it must be acknowledged that this is not an objective method of quantification.

Mental state abnormalities and diminished responsibility

To demonstrate the issues relevant to diminished responsibility that may be associated with different types of mental state abnormalities, two hypothetical case examples are used here. No assumption is being made about whether a defence in such cases would succeed.