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Manifest MadnessMental Incapacity in the Criminal Law$

Arlie Loughnan

Print publication date: 2012

Print ISBN-13: 9780199698592

Published to Oxford Scholarship Online: May 2012

DOI: 10.1093/acprof:oso/9780199698592.001.0001

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Differences of Degree and Differences of Kind: Diminished Responsibility

Differences of Degree and Differences of Kind: Diminished Responsibility

Chapter:
(p.226) 9 Differences of Degree and Differences of Kind: Diminished Responsibility
Source:
Manifest Madness
Author(s):

Arlie Loughnan

Publisher:
Oxford University Press
DOI:10.1093/acprof:oso/9780199698592.003.0009

Abstract and Keywords

This chapter takes up the Janus-faced nature of diminished responsibility with the aim of exposing what kind of difference is encoded in the diminished responsibility doctrine, or, to put it another way, analysing what kind of difference diminished responsibility makes to the individual who raises it. The analysis of the development of a doctrine of diminished responsibility from its origins in nineteenth-century Scotland shows that the sort of difference encoded in the diminished responsibility doctrine is most accurately thought of as one of kind, as opposed to one of degree.

Keywords:   diminished responsibility, legal doctrine, Scotland, nineteenth century

Where successful, an accused pleading diminished responsibility receives a manslaughter rather than a murder conviction.1 As a result, diminished responsibility is typically regarded as partially exculpatory, distinguishing individuals on the basis that both their criminal liability and their criminal responsibility is reduced or impaired, but not abrogated. As I suggest in Chapter 2, useful insights are to be gained by viewing diminished responsibility (and infanticide) as Janus‐faced, both partially exculpatory and partially inculpatory, or sliding between my two subcategories of exculpatory and non‐exculpatory mental incapacity doctrines. As I discuss in that chapter, this involves thinking about diminished responsibility in relation not only to (the offence of) murder but also to (the exculpatory doctrine of) insanity, which, if successful, results in a special verdict (‘not guilty by reason of insanity’). In this chapter, I take up this point about the Janus‐faced nature of diminished responsibility with the aim of exposing what kind of difference is encoded in the diminished responsibility doctrine, or, to put it another way, analysing what kind of difference diminished responsibility makes to the individual who raises it. My analysis of the development of a doctrine of diminished responsibility from its origins in nineteenth‐century Scotland shows that the sort of difference encoded in the diminished responsibility doctrine is most accurately thought of as one of kind, as opposed to one of degree.

In brief, first appearing at a time when the boundary between factors relating to liability and mitigating factors remained porous, diminished responsibility developed as a free‐standing mental incapacity doctrine, and formalized into a discrete partial defence to murder in the Scottish law. Even as a jurisprudence developed around diminished responsibility following its import to England and Wales—with the concept developing in a dialectical relation with both M'Naghten insanity and lay knowledge about incapacity—the precise way in which an ‘abnormality of mind’ (now, an ‘abnormality of mental functioning’) affected an individual for criminal law purposes remained ambiguous. In the decades since diminished responsibility was first introduced to England and Wales, the ambiguity surrounding the doctrine (does it relate to the actor or the act?) has come to be more (p.227) problematic, generating a close practical and strategic reliance on expert psychiatric and psychological evidence (and thus on expert knowledge), and, most recently, the momentum for a change in the law to include an express requirement that a quasi‐causal relationship exist between the abnormal mental state and the prohibited act of killing. The result of these developments over time is that the difference diminished responsibility makes is no longer under‐determined, but over‐determined.

‘Without being insane in the legal sense’: the Development of Diminished Responsibility in Scotland

Three aspects of Scots criminal law at the end of the nineteenth century were significant in the formation of what would come to be called diminished responsibility. The first of these was the Scots law on insanity, which encompassed a notion of partial insanity, providing that a ‘penalty should be reduced in proportion to the degree of impairment of responsibility—the worse the accused's mental condition the less the sentence’.2 A defendant's partial insanity could be taken into account via particular sentencing practices, and it was these practices which formed the second aspect of the Scots criminal law that facilitated the development of a doctrine of diminished responsibility. By contrast with England, where the Criminal Lunatics Act 1800 had been enacted to regulate the sentencing of insane defendants and those found ‘insane on arraignment’, contemporary Scots sentencing practices concerning those with abnormal mental states were more informal and flexible. From the early nineteenth century, Scots courts took ‘mental weakness’ into account as a factor that might mitigate sentence or lead to a recommendation of mercy.3 According to Gerald Gordon, by the mid‐nineteenth century, it was ‘common’ for juries to make ‘recommendations to mercy on the ground of mental weakness’.4 The informality of criminal law practices at this stage meant that there was nothing unique about ‘mental weakness’ and thus, in Gordon's words, ‘no “ (p.228) doctrine” was necessary’ to account for mitigation on the basis of diminished responsibility.5

These two aspects of Scots criminal law in the middle of the nineteenth century were accommodated within what constituted the third basis for the development of diminished responsibility, the category of culpable homicide in the Scots law of homicide.6 In the first half of the nineteenth century in Scotland, culpable homicide was used as a category of offence by what Lindsay Farmer labels ‘an increasingly organized and interventionist prosecutorial system’, to charge defendants in a range of situations that had not previously been prosecuted, such as accidental death caused by machinery or vehicles.7 As the category of culpable homicide grew in importance over the course of the century, it came to be defined in positive terms, ‘on the basis of the degree of blame of each of the accused as this could be determined from the circumstances of the case’.8 As Farmer argues, the need to distinguish between the defendant's act and his or her state of mind led to the formulation of a test by which the defendant's state of mind could be judged.9 Judges had to articulate both the distinctiveness and the relevance of mental states generally, and ‘mental weakness’ in particular, to the ascription of criminal responsibility. In Gordon's words, the ‘anomalous position of the fixed penalty for murder meant that the effect of diminished responsibility on sentence had to be “justified”, to be “rationalized” ’.10 What would come to be called diminished responsibility had to be given some conceptual basis in the law of murder, which would explain why a conviction for culpable homicide was more appropriate in a particular instance than a conviction for murder. Significantly (although for reasons which seem unclear), it was in the law of homicide, ‘rather than in any more fashionable scientific theory of alienation’, that a justification for the idea that mental states could affect culpability was sought.11

It was against this backdrop that the two decisions that mark the origins of diminished responsibility (a term in use since at least 184412) appeared. These two decisions illustrate the interaction of the Scots law of insanity, sentencing practices, and the structure of the law of homicide in facilitating the development of diminished responsibility in Scotland. The first of these decisions is Alexander (p.229) Dingwall, concerning an accused charged with the murder of his wife.13 Lord Deas, who played a central role in the emergence of diminished responsibility, presided over the trial. In his summing up, Lord Deas set out the grounds for a verdict of culpable homicide, as opposed to murder, stating that these grounds included the ‘unpremeditated and sudden nature of the attack’, ‘the prisoner's habitual kindness to his wife’, the fact that ‘there was only one stab wound’, and that ‘the prisoner appeared not only to have been peculiar in his mental constitution but to have had his mind weakened by successive attacks of disease’, which might have been caused by ‘a stroke of the sun in India’.14 Lord Deas concluded by stating that ‘the state of the mind of a prisoner…might…be an extenuating circumstance, although not such as to warrant an acquittal on the ground of insanity’.15

In the same year as Dingwall, Lord Deas presided over the case of McLean, concerning an accused charged with theft by housebreaking.16 McLean was convicted, but it was with a recommendation to leniency on the basis that he had a ‘weak intellect’.17 In his speech, Lord Deas stated that it was appropriate for a judge to take into account mental weakness in passing sentence, whether or not the jury had recommended leniency. Lord Deas stated:

[W]ithout being insane in the legal sense, so as not to be amenable to punishment, a prisoner may yet labour under that degree of weakness of intellect or mental infirmity which may make it both right and legal to take that state of mind into account, not only in awarding the punishment, but in some cases, even in considering within what category of offences the crime shall be held to fall.18

As these brief extracts suggest, the condition of the two defendants in Dingwall and McLean did not amount to legal insanity. Lord Deas’ differentiation between ‘weakness of intellect or mental infirmity’ and insanity might suggest that the latter was clear. However, by way of contrast with England, there was no ‘precise test of criminal insanity’ in Scotland at this time: the M'Naghten Rules were ‘merely interesting news’.19 As it was, Dingwall and McLean's impaired mental states were among a number of factors to be considered, such as the accused's character and the nature of the killing, each of which might reduce his or her charge from murder to culpable homicide.20 Reflecting the absence of a robust distinction between defences (which impacted on conviction) and mitigating factors (which (p.230) impacted on sentence), an accused's impaired mental state was grouped together with what are now regarded as general mitigating factors (such as good character).

For my purposes in analysing the sort of difference diminished responsibility makes, what is notable about Lord Deas’ directions in Dingwall and McLean is their imprecision. Lord Deas did not regard mental abnormality as affecting criminal responsibility in a unique way.21 Thus, it was in a rather indeterminate way that an impaired ‘mental constitution’ was held to warrant conviction of culpable homicide as opposed to murder. According to Lord Deas, these abnormal states had a profound if unspecified effect on the defendants’ liability for their offences. Even as Lord Deas’ views about diminished responsibility ‘gained ready acceptance’ among his contemporaries in the decades after the decisions of Dingwall and McLean,22 the Scots concept of diminished responsibility remained open‐textured and flexible. Various mental states were articulated as the base of the defence: phrases such as ‘mental weakness’, ‘mental aberration’, ‘unsoundness of mind’, and ‘partial insanity’ peppered the case law.23 These labels for mental abnormality short of insanity, each of which was partly descriptive and partly prescriptive, were premised on the idea that there was something distinct about diminished responsibility and that such a mental state had a qualitative significance for criminal liability. What was clear was that the abnormal ‘state of mind’ had to pertain at the time of the killing (recently, this temporal connection has been replaced with a quasi‐causal requirement, as I discuss below). But the precise way in which ‘the state of mind of a prisoner…might…be an extenuating circumstance, although not such as to warrant an acquittal on the ground of insanity’24 remained indeterminate. This indeterminacy about the precise nature of the difference diminished responsibility makes would linger after diminished responsibility was introduced in England and Wales in the form of statutory doctrine.

Setting the development of diminished responsibility at this juncture in the middle of the nineteenth century in a larger frame, it is possible to detect, in diminished responsibility, traces of broader changes in the idea of criminal responsibility in English and Scots law that were taking place around this time. As Nicola Lacey argues in relation to the English law, between the eighteenth and twentieth centuries, a loose or thin formulation of criminal fault, whereby responsibility was assumed, gave way to a thicker and more robust concept of fault or mens rea which was itself the object of investigation at trial.25 The references to the defendant's ‘weakness of intellect or mental infirmity’ that were included in the directions given in Dingwall and McLean reflect a capacity conceptualization of criminal fault. In addition, it is notable that these abnormal mental states were regarded as something that, in Farmer's words, ‘could be proved as a question of (p.231) fact’.26 The development of diminished responsibility in Scots law was premised on the ‘factualisation’ of mens rea, and may be regarded as an instance of what Lacey has referred to as the rise of a ‘primarily capacity‐based and heavily psychologised notion of mens rea’ that marked ‘the core of the late modern general part of the criminal law’.27 This development produced a conception of criminal responsibility that could be ‘explicated in technical, legal terms, and hence legitimated as a form of specialist knowledge underpinning an impersonal mode of judgment’.28

Precisely what constituted diminished responsibility was subjected to further explication in the first half of the twentieth century, prior to its import to England and Wales. Scots courts attempted to define and limit the scope of diminished responsibility. In the decision of Savage in 1923, Lord Alness gave this definition of diminished responsibility:

It is very difficult to put in a phrase, but it has been put this way: that there must be aberration or weakness of mind; that there must be some form of mental unsoundness; that there must be a state of mind which is bordering on, though not amounting to, insanity; that there must be a mind so affected that responsibility is diminished from full responsibility to partial responsibility—in other words, the prisoner in question must be only partially accountable for his actions. And I think one can see running through the cases that there is implied…that there must be some form of mental disease.29

This address to the jury became the authoritative test of diminished responsibility in Scotland. The factors enumerated by Lord Alness were regarded as cumulative in nature, and the test for diminished responsibility became difficult to satisfy.30 This strict approach to diminished responsibility has been revised in recent decades, with the High Court in Galbraith concluding that, in order to be successful, a diminished responsibility plea did not require that all the Savage conditions be met or that the defendant's condition amount to one bordering on insanity.31

(p.232) As the Savage decision suggests, by this point in time, diminished responsibility was conceptualized ‘as doing something to the “quality of the act” as if it were an exculpatory plea and not a plea in mitigation of sentence’.32 But I suggest that this constitution as an exculpatory plea rather than a plea in mitigation was contingent. It was dependent on the restriction of diminished responsibility to murder, and a tight but still unspecified connection between the abnormal mental state and prohibited act. As a result, although still somewhat amorphous, the kind of difference diminished responsibility made stretched across any neat distinction between the act and the actor. The idea that diminished responsibility affected the ‘quality’ of a defendant's act, from which it was difficult to disentangle the actor him or herself, would give mental disorder (and, eventually, expert medical evidence) an enhanced position in the doctrine. Once a statutory version of the doctrine was introduced into England and Wales, mental disorders, and expert evidence of them, would together come to play a significant role in decision‐making around diminished responsibility.

‘In the light of modern knowledge’: the Introduction of Diminished Responsibility in England and Wales

The first serious consideration of diminished responsibility by English authorities dates from the middle years of the twentieth century, when the Royal Commission on Capital Punishment (1949–1953) considered whether to import the Scots law into England and Wales. The Scots law of diminished responsibility would have been known to English legal commentators from around the time of its inception in the second half of the nineteenth century. As I discuss in Chapter 5, a broad ranging debate about the M'Naghten Rules took place in England over the last decades of the nineteenth century, and, although this debate encompassed issues such as volitional impairment, punishment versus treatment, and the culpability of insane defendants, some sort of doctrine of diminished responsibility affecting the category of offence and/or sentence was not discussed.33 By the time of the Royal Commission mid‐century, criticism of the M'Naghten Rules had amplified and several professional medical organizations had come to advocate the introduction of diminished responsibility as a remedy for its deficiencies.34 Having received submissions both in favour of and against the adoption of (p.233) diminished responsibility, the Royal Commission recommended against introducing diminished responsibility into the English and Welsh law, although it observed that diminished responsibility operated satisfactorily in Scotland.35

Despite the conclusion of the Royal Commission, diminished responsibility was introduced into the law of England and Wales within the space of a few years. In the wake of the publication of the Royal Commission report, a group of barristers and Members of Parliament formed the Heald Committee to push for change in the criminal law. The Heald Committee produced a report, Murder: some suggestions for the reform of the law relating to murder in England (1956), which recommended a set of changes to the criminal law, including changes relating to the law of insanity.36 Rather than attempt to improve the M'Naghten Rules, the report recommended diminished responsibility be adopted, to be available to reduce a charge of murder to manslaughter. It was the Heald Committee report that pushed the Cabinet to examine its attitude to diminished responsibility and the Heald proposal that was taken up by Parliament in the 1956–57 parliamentary session. The Homicide Bill introduced in that session contained a partial defence of diminished responsibility, available only to murder, and also restricted the scope of the death penalty to certain kinds of murder. The parliamentary debates on the Bill indicate that it was capital punishment rather than diminished responsibility that was the major preoccupation at the time—the provision on diminished responsibility seems to have been uncontroversial and became law with the passage of the Homicide Act 1957.

The 1957 Act provided that a defendant charged with murder would be liable for manslaughter instead if he or she suffered from an ‘abnormality of mind’ that ‘substantially’ impaired his or her ‘mental responsibility’ for the killing.37 Section 2 of the Act stated that the burden of proof of diminished responsibility lay with the defence and that, where successful, a defendant who pleaded diminished responsibility would be convicted of manslaughter rather than murder (a conviction attracting sentencing discretion).38 The section stipulated that the requisite ‘abnormality of mind’ had to arise from ‘arrested or retarded development (p.234) of mind’ or ‘any inherent causes’ or be ‘induced by disease or injury’. The availability of diminished responsibility was (and remains) narrowly circumscribed around murder.39

The introduction of diminished responsibility into English and Welsh criminal law was a reaction to the restricted nature of the M'Naghten Rules governing insanity. As a number of commentators note, the introduction of diminished responsibility was intended to counter the effects of the narrow, cognitive M'Naghten test for insanity.40 In a comment that presaged the subsequent development of a jurisprudence of diminished responsibility—in a dialectical relation with both M'Naghten insanity and lay understandings of incapacity—Major Lloyd‐George stated in his Second Reading Speech in the House of Commons, that the ‘new defence’ will be open to:

those who, although not insane in this [M'Naghten] legal sense, are regarded in the light of modern knowledge as insane in the medical sense, and those who, not insane in either sense, are seriously abnormal, whether through mental deficiency, inherent causes, disease or injury.41

The import of diminished responsibility from north of the border seems to have provided a convenient means of injecting flexibility into the law on insanity and of effectively amending insanity (as it related to murder) with limited risk. As Keith Smith argues, the proposal to introduce the Scots doctrine was appealing in that ‘rather than being a complete conceptual leap in the dark, it had been tested in action (albeit as part of the Scots legal system) for nearly a century without noticeable subversion of orthodox notions of criminal responsibility’.42

(p.235) The Current Doctrine of Diminished Responsibility

As a result of the Coroners and Justice Act 2009, the law of diminished responsibility has been amended. The revised law provides that diminished responsibility is available where a killing is explained by an ‘abnormality of mental functioning’, arising from a ‘recognised medical condition’, which has ‘substantially impaired’ the defendant's ‘ability’ to understand the nature of his or her conduct, form a rational judgment, or exercise self‐control, and the ‘abnormality provides an explanation for the defendant's act in doing or being a party to the killing’.43 This change in the law was the outcome of the Law Commission's review of the law of homicide. The Law Commission proposed modernizing the definition of diminished responsibility ‘so that it is clearer and better able to accommodate developments in expert diagnostic practice’.44 The Commission proposed that diminished responsibility be retained in the same form—as a partial defence—reducing first degree murder to second degree murder according to their proposed (but as yet unimplemented) restructure of homicide.45 Given that the mandatory life sentence would apply to first degree murder, a successful diminished responsibility plea would continue to provide a means of introducing discretion in sentencing, as had been the case under Section 2(1) of the Homicide Act 1957, as originally drafted.

In order to offer an analysis of diminished responsibility up to the current era, and to lay the ground for a discussion of the way in which diminished responsibility is decided in the next section, I offer a close discussion of the current law here. There are four components of the new diminished responsibility doctrine, and I structure my discussion around them.

(i) ‘Abnormality of mental functioning’

A defendant seeking to raise diminished responsibility must suffer from an ‘abnormality of mental functioning’, the phrase that replaced ‘abnormality of mind’, which was used in the 1957 Act. The phrase ‘abnormality of mental functioning’ had been proposed by the Law Commission, on the basis that psychiatrists prefer ‘mental functioning’ to ‘mind’.46 The Law Commission's reasoning suggests that this new phraseology represents an update of the law, but not one that is intended to radically change diminished responsibility. Given this, but mindful of the other (p.236) changes to diminished responsibility made by the 2009 Act (which I discuss below), it seems likely that, like ‘abnormality of mind’, ‘abnormality of mental functioning’ will be defined broadly.47 Whether a particular defendant has the requisite abnormal mental state is a question of fact for the jury, although the question of whether a particular clinical condition can give rise to such a state is a question of law.48 A diverse set of clinical conditions had been held to ground an ‘abnormality of mind’ for the purposes of diminished responsibility.49

The scope of the phrase ‘abnormality of mind’ had developed in part in a dialectical relation with insanity, and specifically with the ‘disease of the mind’ limb of the M'Naghten Rules. Early judicial discussion of the phrase ‘abnormality of mind’ drew express comparisons with insanity, according to which the phrase was defined in contradistinction with ‘disease of the mind’. In Byrne, the first diminished responsibility case to go before the Court of Criminal Appeal, ‘abnormality of mind’ was interpreted to encompass psychopathy, thus ensuring that volitional incapacity could found a claim of diminished responsibility. In Byrne, which involved a defendant who had killed a woman and mutilated her body, all the medical evidence suggested that Byrne was a sexual psychopath who had impulses that were very difficult or impossible to control. The trial judge directed the jury to the effect that, if Byrne had an impulse or urge that was so strong that he found it difficult or impossible to resist, but that he was otherwise normal, diminished responsibility was not available to him.50 In allowing Byrne's appeal, and substituting a conviction of manslaughter for murder, the Court of Criminal Appeal stated that the phrase ‘abnormality of mind’ appeared to be:

wide enough to cover the mind's activities in all its aspects, not only perception of physical acts and matters and the ability to form a rational judgment as to whether an act is right or wrong, but also the ability to exercise will‐power to control physical acts in accordance with that rational judgment.51

According to the Court of Criminal Appeal, an ‘abnormality of mind’ that results in an ‘inability to exercise will power to control physical acts…is…sufficient to entitle the accused to the benefit’ of diminished responsibility.52 In the Byrne (p.237) decision, the Court side‐stepped the well‐rehearsed argument that volitional incapacity was problematic because of the difficulty of distinguishing between impulses that were unable to be resisted and those that were merely unresisted. According to the Byrne Court, whether mere difficulty, as opposed to inability, to control one's acts, will ground a plea of diminished responsibility will depend on whether the difficulty is ‘so great’ as to amount to a ‘substantial impairment of the accused's mental responsibility for his act’.53 The Court concluded that the question of precisely when the difficulty of controlling oneself is sufficiently great is ‘scientifically insoluble’ and must be determined by the jury ‘in a broad, common‐sense way’.54

This reasoning exposes the other side of the dialectical relation in which a jurisprudence of ‘abnormality of mind’ developed. ‘Abnormality of mind’ also developed in relation to lay or non‐expert attitudes and beliefs about mental incapacity. Although it may have been prompted at least initially by the uncertain status of the M'Naghten Rules in Scotland,55 referencing ‘abnormality of mind’ to lay rather than legal meanings of insanity constitutes an attempt to both update and legitimate the law on exculpatory abnormality. In Byrne, the Court referred with approval to the Scots case law on diminished responsibility, which provided that ‘substantially impaired’ ‘mental responsibility’ involves a ‘mental state which in popular language (not that of the M'Naghten Rules) a jury would regard as amounting to partial insanity or being on the border‐line of insanity’.56 Given the Byrne Court's notable confidence in lay evaluation of a ‘scientifically insoluble’ issue (of unresisted versus unable‐to‐be‐resisted impulses), it is clear that lay or non‐expert as well as expert medical knowledge about abnormality is relevant to the inquiry about what constitutes ‘abnormality of mind’ for the purposes of diminished responsibility. Indeed, this is the import of Major Lloyd‐George's comment, extracted in full above, that the new defence of diminished responsibility was to be open to those who were insane in the ‘legal sense’, the medical sense, and ‘those who, not insane in either sense, are seriously abnormal’.57

(p.238) The development of an expansive jurisprudence of ‘abnormality of mind’, encompassing volitional incapacity and independent of M'Naghten insanity, is, to a significant extent, a product of the restricted scope of diminished responsibility as a partially exculpatory doctrine available only to murder (as opposed to a full exculpatory doctrine, like self‐defence, available across the board of criminal offences). Because a successful plea of diminished responsibility does not result in a complete acquittal, the consequences of accommodating volitional incapacity here are more circumscribed than if it was a part of the law of insanity (which was haunted by the spectre of volitional incapacity from the nineteenth century until the inter‐war era58). In addition, and for my purposes, most interestingly, the tight circumscription of the scope of diminished responsibility around the act of killing also permits lingering ambiguity about the precise effect an ‘abnormality of mental functioning’ has (does it affect the act or the actor or either/both?). I return to this point below.

(ii) ‘A recognised medical condition’

‘A recognised medical condition’ provides the aetiology of the relevant ‘abnormality of mental functioning’. In the 1957 version of diminished responsibility, the question was whether the ‘abnormality of mind’ was the result of one of a tripartite set of causes, ‘a matter to be determined on expert evidence’.59 The 1957 version of diminished responsibility had required that the defendant's ‘abnormality of mind’ arise from either ‘a condition of arrested or retarded development of mind’, ‘any inherent causes’ or ‘disease or injury’.60 In its reform proposal, (which introduced (p.239) the phrase ‘a recognised medical condition’), the Law Commission stated that an advantage of the new phrase was that it ensured that the law was no longer constrained by a ‘fixed and out‐of‐date set of causes’.61 It seems likely that the new terminology will mean that diminished responsibility will continue to be wide enough to accommodate both mental disorders and physical disorders that have an impact on mental functioning.62 However, R M Mackay has posited that, with its reference to ‘a recognised mental condition’, the reformulated doctrine of diminished responsibility contained in the Coroners and Justice Act 2009 may narrow the scope of the law, to exclude, for instance, so‐called ‘mercy killing’ cases. Mackay posits that the new phraseology may work to prevent the ‘benevolent conspiracy’ between the court and experts that was possible under the obscure wording of the old diminished responsibility doctrine.63

In its previous incarnation (under the tripartite aetiology that applied until 2009), diminished responsibility was interpreted so as to exclude those who might be regarded as culpable for their diminished condition. Exposing the significance of moral culpability in the law relating to intoxication, those individuals whose ‘abnormality of mind’ and impaired mental responsibility arose from intoxication fell without the boundaries of diminished responsibility.64 The courts also prevented intoxication from supplementing the presence of other factors that, in combination, might have brought the defendant within the bounds of diminished responsibility.65 But, unlike intoxication, the disease of alcoholism (or alcohol dependency syndrome) had been held to be an ‘inherent cause’ for the purposes of diminished responsibility. Until recently, the question of what constitutes alcoholism has been interpreted narrowly. In a way that reflected a ‘black and white’ approach to impaired control, this approach to alcoholism meant that unless the defendant was wholly incapable of resisting the impulse to drink, he or she could not plead diminished responsibility on the basis of his or her disease.66 However, in the recent decision of Stewart, the court recognized that, even in the (p.240) absence of evidence of brain damage, ‘at some levels of severity, what might appear to be voluntary drinking might be inseparable from the defendant's underlying [alcohol dependency] syndrome’, and thus be part of such a syndrome, and able to form the basis of a diminished responsibility plea.67

Viewed with the kind of difference invoked by diminished responsibility in mind, the restrictions on the scope of this part of the doctrine take on a particular gloss. The use of the aetiology of mental ‘abnormality’ to exclude consideration of intoxication and merely transient abnormal conditions (and to circumscribe consideration of alcoholism) for the purposes of diminished responsibility represents an attempt to delimit the exculpatory scope of diminished responsibility. In addition, over and above this, it has the effect of ensuring that the doctrine is based on qualitative as opposed to merely quantitative impairment. I take up this point in the next subsection, concerning the specific kind of impairment which must result from ‘a recognised medical condition’.

(iii) ‘Substantially impaired’ D's ‘ability’ to Understand the Nature of the Conduct, Form a Rational Judgment or Exercise Self‐Control

The third component of diminished responsibility relates to the specific kind of effect a defendant's ‘abnormality of mental functioning’ should have on him or her. Here, the relevant part of the provision centres on an idea of the defendant's ‘ability’ (the term that replaces reference to an individual's ‘mental responsibility’, which had been the terminology of the 1957 version of diminished responsibility68). The use of the term ‘ability’ in the newly‐formulated provision may have resulted from its use by Lord Parker CJ in Byrne, who stated that the reference to ‘mental responsibility’ in the 1957 version of the doctrine required the jury to consider ‘the extent to which the accused's mind is answerable for his physical acts’, including ‘the extent of his physical ability to exercise will power to control his physical acts’.69 In relation to ‘ability’, the statutory provision contains two subparts—one that relates to the extent of the requisite effect on a defendant (‘substantially impaired’) and the other that relates to the human capacities that (p.241) must be affected (‘to understand the nature of D's conduct; to form a rational judgment; or to exercise control’). In relation to the extent of the effect on the defendant, it seems likely that ‘substantially impaired’ will be accorded the same meaning as it was given per the 1957 formulation, given the use of the same phrase in the new Act. ‘Substantially impaired’ has been held to mean that the requisite impairment need not be total, but must be more than ‘trivial or minimal’.70 In relation to the types of capacities that must be affected—encompassing cognitive and volitional capacities—which are spelled out here for the first time, it is notable that each of the elements appears to be inspired by Byrne.71

The third component of diminished responsibility, ‘substantial impairment’, is the centre of gravity of the doctrine. It is through this component of diminished responsibility that the doctrine has been able to accommodate a range of levels of culpability because, if the plea is granted, the impairment is thought to satisfy a certain threshold.72 In normative criminal law scholarship, the requirement that the defendant's ‘abnormality of mental functioning’ be ‘substantially impaired’ is regarded as the moral‐evaluative aspect of diminished responsibility.73 So, approached from this perspective, in effect, the doctrine requires that the defendant's ‘abnormality’ is of such consequence in the context of the offence that his or her ‘legal liability for it ought to be reduced’.74 As this suggests, and as several commentators note, in practice, the scope of diminished responsibility expands and contracts depending on the morality of the case,75 or on the basis of the sympathy the defendant elicits, perhaps accounting for the success (p.242) (at least under the old version of the doctrine) of so‐called ‘mercy killers’ who raise diminished responsibility.76

The ‘substantially impaired’ component of diminished responsibility is typically, if implicitly, understood to mean that what the doctrine connotes, in the abstract and in practice, is a certain degree of impairment. As the Court stated in Walden, the term ‘substantially impaired’ ‘connotes a question of degree and questions of degree are questions of fact in each case’.77 The prominence of the language of degree in diminished responsibility has generated a predominant scholarly understanding that it connotes a quantitative rather than qualitative difference. But I suggest this scholarly understanding has obscured another, deeper sense of difference connoted by diminished responsibility—difference in kind. On its face, this idea of the difference connoted by diminished responsibility seems counter‐intuitive because the law is replete with the language of degree—evident in the name of the doctrine itself as well as in elements such as ‘substantially impaired’. But, when examined as a whole, and taking into account the ways in which diminished responsibility is proved (with close reliance on expert evidence and clinical diagnoses), diminished defendants can be seen to be constructed as different in kind, rather than degree. I discuss this point in the final section of this chapter.

(iv) ‘Abnormality of mental functioning’ Provides ‘an explanation for D's act in doing/being a party to the killing’

The reformulated diminished responsibility provision introduced by the Coroners and Justice Act 2009 stipulates that there must be a quasi‐causal relationship between the defendant's ‘abnormality of mental functioning’ and his or her acts in relation to the killing. In providing that the ‘abnormality of mental functioning’ offers ‘an explanation’ (as opposed to ‘the’ or ‘the sole’ explanation) for the killing, the new diminished responsibility provision contemplates that only those individuals whose ‘abnormality of mental functioning’ caused, or was ‘a significant contributory factor in causing’, the relevant conduct will be able to succeed in their claim for a partial defence.78 This new component of the doctrine of diminished responsibility followed the Law Commission's recommendations that a defendant's abnormality of mind (or developmental immaturity, according to their formulation) must form ‘an explanation’ for his or her conduct.79 A quasi‐causal connection between the defendant's ‘abnormality of mental functioning’ and (p.243) his or her homicidal acts means that the defendant's mental abnormality must precipitate the killing he or she commits.80 With this new quasi‐causal requirement, diminished responsibility has moved closer to infanticide, which, as I suggest in Chapter 8, works on the implicit assumption that the defendant woman's actions in killing her child are caused actions.

The 1957 version of diminished responsibility did not specify a particular connection between a defendant's ‘abnormality of mind’ and his or her ‘acts or omissions in doing or being party to the killing’. But, those in favour of the recent reform in this direction argued that this was something like a de facto requirement of diminished responsibility.81 However, the requirement of a quasi‐causal connection between the defendant's ‘abnormality’ and his or her homicidal acts is just one of several possible formulations of the relationship between the abnormal mental state and criminal conduct under diminished responsibility. On the one hand, the connection between ‘abnormality of mind’ and a defendant's homicidal conduct may be merely temporal, that is, the doctrine may require that the defendant suffer from an ‘abnormality of mind’ at the time he or she kills. There is also another possible formulation of the connection between ‘abnormality of mind’ and the defendant's homicidal acts—his or her abnormality may mean that he or she did not form the requisite mens rea for murder. Diminished responsibility provisions constructed in this way—as putative rather than affirmative defences—are in place in other jurisdictions.82

It is possible to mount a critique of the introduction of a quasi‐causal requirement to diminished responsibility on several bases. On an abstract level, an approach that assumes or requires that mental abnormality cause the killing conflates two separate ideas—excuse and causation. As Michael Moore argues in relation to insanity, properly understood, exculpatory doctrines based on mental (p.244) incapacity excuse defendants because of their incapacity, not because that incapacity causes criminal acts. According to Moore, conflating causation and excuse obscures the legal (and moral) basis of excusing in either incapacity or lack of opportunity.83 On an empirical level, it is arguable that diminished responsibility had not been restricted to those defendants whose abnormalities caused them to kill. According to G R Sullivan, empirically, most pleas of diminished responsibility involve a claim that the ‘abnormality of mind’ precipitated the killing, but, in some cases, such as those in which the defendant is intellectually impaired, the issue of what caused the defendant to kill is severable from an inquiry into whether he or she was responsible for that killing.84 Given this, and although more than one cause can be considered under the new formulation, the approach to causation taken in the reformulated diminished responsibility provision is likely to narrow the scope of diminished responsibility.

Viewed in the light of my assessment of the historical development of diminished responsibility, the inclusion of a causation requirement appears as an over‐determination of what had been an under‐determined aspect of the doctrine. As discussed above, there are good reasons to conclude that the foundational Scots version of diminished responsibility actually relied only on a temporal connection between mental abnormality and the act of killing. This temporal connection meant that the defendant's ‘abnormality of mind’ must have been operative or in some way pertained at the time of the killing, but did not mean that it precipitated the killing (the stricter requirement). This type of connection left open the question of precisely how a defendant's ‘abnormality of mind’/‘abnormality of mental impairment’ impairs his or her criminal responsibility. It was this looser type of connection that seems to have been envisaged at the time of the development of the Scots plea of diminished responsibility. Up until 2009, the effect of the looser connection between abnormality and criminal responsibility was to raise expert medical evidence to a position of prominence as it provided a means by which the descriptive issue of the defendant's mental state (‘abnormality of mind’ resulting from one of the specified causes) and the evaluative issue (whether that state amounted to a ‘substantial’ impairment of ‘mental responsibility’) could be joined. The new version of the plea seems set to continue to depend on expert evidence. I pick up this point again in the next section of this chapter.

Where causation does seem to be an appropriate consideration for diminished responsibility is in relation to those cases in which appellants argue that their mental states were such that they were unable to instruct their lawyers to raise diminished responsibility at trial. These cases concern the ‘rare’ instances in which it is argued that ‘fresh evidence shows that the appellant's responsibility at the time of killing was indeed sufficiently diminished…and that there is a persuasive reason why the defence was not advanced at trial’.85 In relation to the latter, the question is (p.245) if the ‘mental illness itself’ was a ‘material cause’ of the decision not to run diminished responsibility.86 In the joint decision of R v Erskine; R v Williams, the Court of Appeal held that there was ‘unequivocal contemporaneous evidence’ which suggested that the decision in Erskine's trial not to advance diminished responsibility was not a strategic decision but was ‘irredeemably flawed’.87 By contrast, in R v Latus, the Court held that the decision not to run diminished responsibility was caused not by the illness but by a tactical choice not to allow the defence to be investigated.88 In the latter case, the appeal was denied.

Professional Actors and Expert Knowledge: Deciding Diminished Responsibility

Legal experts—judges, prosecution, and defence counsel—and medical experts now dominate decision‐making in relation to diminished responsibility. In terms of legal experts, on their face, the rules about the way in which diminished responsibility may be raised in court suggest the primacy of defence counsel. Reflecting the ‘long established policy of the law that the defendant is presumed to be in full possession of his faculties until the contrary is shown’, it is up to the defendant to raise diminished responsibility.89 Because a plea of diminished responsibility entails admitting that the defendant did the actus reus with the mens rea (thus exposing him or her to conviction for murder), diminished responsibility has been called an ‘optional defence’.90 The ‘optional defence’ status of (p.246) diminished responsibility means that the prosecution may not raise diminished responsibility, unless the defence puts the defendant's state of mind in issue by raising insanity, in which case the prosecution may raise diminished responsibility as an alternative.91 The judge may not raise diminished responsibility: the most the judge may do (‘at least in cases where the defendant is represented by counsel’) is to point out the evidence of diminished responsibility to the defence, leaving it to them to decide whether to make the plea.92 Possibly reflecting the Scots law, the burden of proof for diminished responsibility is on the defendant, and the standard of proof is the legal standard.93

Although the rules about raising diminished responsibility suggest that defence counsel occupy the most prominent position regarding diminished responsibility, taking into account legal practices, the picture is more equivocal. As a result of changes in the way in which the claims to diminished responsibility are decided, there has been a shift in the balance of decision‐making in diminished responsibility cases toward the prosecution, who determines whether to contest a plea of dimin (p.247) ished responsibility, and the judge who accepts or rejects any prosecution–defence arrangement.94 This shift has occurred with the rise in the importance of pre‐trial decision‐making. In a move that seems to reflect institutional pressure on prosecution services to process cases speedily, the requirement that a plea of diminished responsibility go to the jury was abrogated by the Court of Appeal in Cox, decided in 1968. In this case, the Court of Appeal concluded that, in cases where ‘the medical evidence available, in the possession of the prosecution as well as the defence’, indicated ‘perfectly plainly’ that it would have been proper to accept a plea of diminished responsibility, it is open to the prosecution to accept that plea and avoid a murder trial.95

These changes to the way in which diminished responsibility is decided heralded a significant change in the practical operation of the law. In a way that prefigures the recent changes to the way in which unfitness to plead is decided, which I discuss in Chapter 4, the rule permitting the prosecution to accept a plea of diminished responsibility in (what are at least formally) unequivocal cases means that the issue of the defendant's mental abnormality is in the hands of legal actors and medical professionals. Thus, even though it is not possible to charge diminished responsibility manslaughter, the law is such that the situation is now as close to that as possible without such a change. In those cases in which the medical evidence is ‘perfectly plainly’ to the effect that the defendant killed under conditions of diminished responsibility, the doctrine in effect becomes a preliminary issue, determining whether or not a trial will go ahead. In the decades since the decision in Cox, decision‐making in relation to diminished responsibility has altered such that the majority of diminished responsibility pleas are now accepted by the prosecution.96

As so many diminished responsibility pleas are accepted prior to trial, the shift in the balance of power between various legal experts has also entailed a shift away from lay evaluation of diminished responsibility claims. In evaluating and adjudicating diminished responsibility claims, lay actors initially had a greater role than (p.248) they now do. When the plea was first introduced into the criminal law in England and Wales, and prior to Cox, all findings of diminished responsibility had to be made by a jury,97 although, unless there was ‘other evidence which can displace or throw doubt on that evidence’, it was not open to the jury to reject unanimous medical evidence of ‘abnormality of mind’.98 But, in those instances where experts differed as to whether the defendant was suffering from ‘diminished responsibility’, the decision to grant or deny the plea lay with the jury. In Byrne, Lord Parker CJ stated that, with regard to the issue of the defendant's ‘abnormality of mind’, ‘medical evidence is no doubt of importance, but the jury are entitled to take into consideration all the evidence including the acts or statements of the accused and his demeanour’.99 Lord Parker CJ went on to state that:

They [the jury] are ‘not bound to accept the medical evidence if there is other material before them which, in their good judgment, conflicts with it and outweighs it, [bearing in mind that] the question involves a decision not merely as to whether there was some impairment…but whether such impairment can properly be called ‘substantial’, a matter upon which juries may quite legitimately differ from doctors.100

The balance between lay people and medical experts evoked in Byrne fell away within a short period of time following the introduction of diminished responsibility into England and Wales. With a majority of diminished responsibility pleas accepted by the prosecution, juries are only involved in the minority of cases—those in which the plea is contested.101

A declining role for lay actors does not sound a knell for lay knowledge. Because legal actors—including judges, prosecution, and defence counsel—rely on lay knowledge of mental incapacity, the role of lay knowledge in criminal process does not begin and end with lay adjudication, meaning that its significance is not coterminous with decision‐making by a jury, for instance. As I discuss in Chapter 3, in relation to the decision‐making around mental incapacity more generally, legal actors can be seen to be lay when it comes to the issue of mental incapacity, although they are in different subject positions when compared with lay people. This is not to deny legal actors their status as experts—but it is to suggest that these individuals are lay vis‐à‐vis mental incapacity. In relation to diminished responsibility, legal actors combine their lay knowledge of incapacity with their expert knowledge of legal processes. Thus, a decision about whether to (p.249) accept a plea of diminished responsibility will involve both a lay knowledge of the relevant condition forming the basis of the plea, and an expert knowledge of the way in which, in the context of all the circumstances of the case, such a plea would be received in court.

Nonetheless, in relation to diminished responsibility, it seems that expert psychological and psychiatric knowledge, and evidence based on it, has a deep significance in this part of the mental incapacity terrain. In this respect, diminished responsibility is similar to insanity, and may be contrasted with intoxication, for instance. This significance is in part a practical one. As the Law Commission recently concluded, expert evidence is ‘crucial’ to the viability of a claim to diminished responsibility.102 Even in the absence of a statutory requirement that expert evidence be adduced in support of a plea of diminished responsibility (contra insanity and unfitness to plead), empirical studies bear out the claim that expert medical evidence is ‘crucial’ in diminished responsibility cases.103 Indeed, it is appropriate to think of expert evidence as a de facto requirement of the plea, placing expert knowledge at its heart. Given this, it is significant that the recent reform to diminished responsibility was accompanied by a renewed emphasis on a clear division of labour between experts and the jury, preserving the ‘ultimate issue’—that the defendant's state was indeed such that he or she was ‘substantially impaired’—as solely one for the jury.104

(p.250) Beyond its practical role in particular cases, expert psychiatric and psychological evidence has a more diffused significance that transcends any specific decision. Various accounts of the role expert evidence plays in relation to diminished responsibility have been offered. In relation to the operation of diminished responsibility, some commentators have suggested that expert evidence operates to expand the scope of the doctrine.105 Another account of the significance of expert medical knowledge for the diminished responsibility doctrine assesses the value of the evidence from a more ideological perspective, suggesting that expert evidence provides a way of manipulating the strictures of legal standards for exculpation.106 Evidence in support of these arguments is provided by the inclusion of homicides which are ‘essentially non‐pathological reactions to stressful life events’ within the bounds of diminished responsibility.107 A third account of the significance of expert medical evidence for diminished responsibility is mounted in terms of the legitimation of legal processes. Here, the significance of expert evidence supports what Tony Ward calls the ‘dual authority of science and lay consensus’, which he argues underpins mental incapacity doctrines such as diminished responsibility historically.108 As this last account suggests, lay as well as expert knowledge is relevant to legitimation: because the (most) controversial claims to diminished responsibility—those in which a plea is not accepted by the prosecution or, more rarely, in which the judge insists on the defendant going to trial on a charge of murder—are those that are adjudicated by a jury, lay knowledge as employed in lay evaluation also performs a legitimating role in relation to diminished responsibility.

(p.251) By way of contribution to this scholarly discussion about expert medical evidence, I suggest that its significance lies in part in its contribution to the particular construction of the subject of diminished responsibility. This becomes apparent when we take a step back to think about knowledge rather than evidence. Here, it is useful to recall my discussion of the kind of difference shared by mental incapacity doctrines. As I discuss in Chapter 2, the process of construction of subjects of the law takes place in and through legal processes. There, I suggest that a particular idea of difference marked defendants relying on mental incapacity doctrines out from other defendants. With regard to diminished responsibility, I suggest that, in making the defendant the subject of specialist language of pathology via the evidence adduced, expert knowledge assists in constructing the diminished defendant as abnormal. The difference invoked is a difference of kind rather than degree. Again, as I discuss in Chapter 2, this qualitative difference is both a requirement of the doctrine and a construction of the individuals (‘diminished’, ‘disabled’, ‘impaired’) who seek to rely on it. When the scholarly frame is extended to take into account the evidentiary and procedural aspects of mental incapacity, it becomes evident that ‘madness’ for criminal law purposes has particular formal qualities, which together mark out the features of the mental incapacity terrain.109

On my analysis of diminished responsibility, beneath the language of degree, another kind of difference is operating. As the Law Commission has put it in relation to the requirement of a ‘medically recognisable basis’ for diminished responsibility:

The distinction between what is normal and abnormal is one of degree and can be difficult to draw. The requirement of a medically recognisable basis provides both a doctrinal justification (that a person suffering a medically recognisable abnormality of mind lacks full responsibility for his or her acts) and a practical limitation on the ambit of the defence. Without it, there would be a serious risk of an ‘evaluative free for all’.110

This requirement of a ‘medically recognisable basis’ delineates the boundaries of diminished responsibility, providing a way of drawing a line at the point of abnormality. But the process of drawing a line is not just about drawing a line at some point—it entails a reconstruction that ensures that the altogether more slippery idea of a quantitative difference (how substantial is substantial?) is made to resemble a firmer qualitative difference, which, on my analysis, is the core of the construction of abnormality for criminal law purposes.

Women seem to be particularly amenable to the construction as abnormal or different in kind via diminished responsibility. Although the recent Law Commission report, Partial Defences to Murder, concluded that diminished responsibility does not operate ‘in a way which involves gender discrimination’,111 there does (p.252) appear to be a multifaceted gender bias in the operation of diminished responsibility. Women are over‐represented among defendants granted the plea.112 In addition, the prosecution is more likely to accept a plea of diminished responsibility for women defendants than for men.113 Women are also more likely than men to be granted the plea at trial.114 Once granted a diminished responsibility plea, women are more likely to be sentenced to probation or supervision orders as opposed to prison sentences.115 The gender bias in the operation of diminished responsibility suggests an underlying consensus about gender, violence, and mental abnormality in both legal processes and lay attitudes and beliefs.116

Concurrent with the changes in the type of actors involved in and the type of knowledges in use in diminished responsibility, its success rate has declined. In the years immediately following the Homicide Act 1957, diminished responsibility was a frequently successful plea.117 As the Law Commission concluded, the figures indicate that there has been ‘a consistent fall in the successful use of diminished responsibility in recent years’.118 Various reasons for the decline have been offered, including that there has been less use for diminished responsibility since the suspension of the death penalty in 1965 (for those types of murder to which it had continued to apply), or that its territory shrunk with the expansive approach to the partial defence of provocation, which prevailed from the 1980s until the early 2000s (I discuss the relationship between diminished responsibility and provocation in the final section of this chapter).119 It is also possible that jurors (p.253) (and perhaps judges and lawyers) have come to be more cynical about the use of labels of mental illness to (partially) exculpate those who are charged with criminal acts.120 Over and above all this, another broader extra‐legal current may be affecting diminished responsibility practices. Given the prominence of expert evidence in the doctrine, it is not unreasonable to suggest that broader social changes associated with late modernity, and its paradigmatic decline in the faith in experts, may play into the reception of claims to diminished responsibility, backed up by the de facto requirement of expert evidence.121 It is notable that it is in this context that a quasi‐causal link between the ‘abnormality of mental functioning’ and the killing—tightening up the relationship between the two—has been introduced.

The Difference Diminished Responsibility Makes

In criminal law scholarship, the predominant way of conceptualizing the difference diminished responsibility makes is in terms of degree. On the basis that certain conditions that affect a defendant's mental capacity are relevant to liability (not just to sentence), but merely reduce rather than abrogate his or her criminal responsibility, extant conceptual analyses of diminished responsibility have coalesced around the idea of diminished responsibility as a partial excuse. On this approach, diminished responsibility is located within a schema of defences by normative type, a schema I discuss in Chapter 2. There are two streams of analysis of diminished responsibility as a partial excuse, and I discuss each in turn.

In the first stream of normative analysis, scholars critique diminished responsibility for its incoherence. For instance, in relation to the 1957 version of the doctrine, Edward Griew argues that diminished responsibility has ‘clumsily compacted’ two ideas—impaired capacity and diminished liability—‘by virtue of a “third idea” ’, reduced culpability.122 According to this analysis, diminished responsibility is structured such that a reduction in sentence depends on a defendant's reduced capacity, which is itself considered to reduce blameworthiness for the killing he or she committed. This structure is criticized because it assumes that (p.254) liability for punishment is something that can be impaired.123 But, as Richard Sparks points out in a widely‐cited analysis, ‘to say that we are less willing to blame…a man if he does something wrong surely does not mean “we are willing to blame him less, if he does something wrong”’.124 Even if liability could be said to be impaired, it is not clear precisely how a defendant's diminished capacity reduces his or her culpability. A number of theorists conclude that the process of reducing liability on the basis of capacity in effect tracks moral‐evaluative lines, meaning that the plea succeeds for those defendants whose liability for killing ought to be reduced.125 Some of the theorists who critique diminished responsibility on the basis of its incoherence conclude that the doctrine should either provide full exculpation,126 or that it should be abolished.127 Other theorists conclude that, despite the theoretical incoherence of diminished responsibility, in practice, it operates in a pragmatic way.128

By contrast, in the second of the two streams conceptualizing diminished responsibility as a partial excuse, scholars defend the doctrine as a coherent instantiation of criminal law principles. Thus, in Herbert Fingarette's words, a successful diminished responsibility plea marks out a defendant who ‘did have sufficient rationality to grasp the criminal purport of his conduct up to a significant point, though not its full heinousness’.129 Here, diminished responsibility is analogous to insanity, merely weakening rather than destroying the propriety of assigning responsibility to a defendant for his or her acts. The difference between diminished responsibility and insanity becomes one of degree.130 In Martin Wasik's analysis, as partial excuses, diminished responsibility and provocation (now replaced by ‘loss of control’) may be thought to be midway on a ‘scale of excuse’, with excuses with the maximum ‘moral pressure for exculpation’ (such as automatism) at one end, and those which ‘may be morally significant [but] are outweighed by practical and policy considerations’ (such as good motive) at the other.131 On this basis, commentators in this stream hold that diminished responsibility and provoca (p.255) tion are ‘not simply strange aberrations of an otherwise clear and self‐evident distinction between excusing conditions and mitigating excuses’132 or, more forcefully, that diminished responsibility ‘falls entirely unexceptionally within the pattern of mental capacity defences’.133

These conceptions of diminished responsibility as, happily or unhappily, midway on a ‘scale of excuse’ have an analogue in the descriptive legal scholarship. Here, diminished responsibility is also depicted as positioned at something of a midway point, but it is viewed as midway between a point at which there is no judicial discretion in sentencing (ie under the mandatory penalty of life for murder) and a point where judicial discretion pertains, but a jury has no jurisdiction over the issue (ie if diminished responsibility is a factor in mitigation only). That is, in this body of legal scholarship, diminished responsibility is a product of the mandatory penalty for murder,134 and the current, only minimally disaggregated law of homicide.135 Viewed in the shadow of the mandatory penalty for murder, and within the broad structure of the law of homicide, on this account, diminished responsibility is regarded as a matter of practical necessity (even if otherwise undesirable). As the sentencing tail is wagging the diminished responsibility dog on this account, it implies that any difference connoted by diminished responsibility is more apparent than real. After all, if it could be dealt with on sentence, then perhaps there is nothing in particular to distinguish diminished defendants from any other defendants.

My analysis of the historical development of diminished responsibility leads me to conclude that diminished responsibility relies on an idea of difference that is most accurately thought of as one of kind rather than one of degree and I suggest that approaching it this way generates a closer understanding of the doctrine than existing accounts provide. Facilitated in part by the restriction of diminished responsibility to a particular kind of act—killing—diminished responsibility does not fit easily into the neat dichotomy between the act and actor that pervades scholarly thinking about defences. In a way that is clearer still with the addition of a requirement that a quasi‐causal relation exist between the ‘abnormality of mental functioning’ and the act of killing under the new version of diminished responsibility, the doctrine does (p.256) something to the ‘quality of the act’ (as discussed above), but in a way that thoroughly implicates the actor. Understanding diminished responsibility to connote a qualitative rather than a quantitative difference takes seriously the notion of abnormality, which has been a consistent feature of the doctrine over time, and helps to account for the significance of expert medical evidence in decision‐making around diminished responsibility. It is this idea of difference—difference in kind rather than difference in degree—that can be seen to underpin the way in which diminished responsibility slides between a doctrine of (partial) exculpation and one of (partial) inculpation: in effect, it is a doctrine that renders the defendant differently liable.

Some evidence in support of this analysis of diminished responsibility is provided by the recent judicial discussions of the appropriate boundary between it and the now‐defunct provocation defence (which was abolished by the Coroners and Justice Act 2009 and replaced with the ‘loss of control’ defence).136 These discussions revolved around the kind of characteristics that could be accorded to the reasonable person and be taken into account for the objective component of provocation.137 As is well known, the provocation defence provided that, where an individual would otherwise be liable for murder, he [sic] could be held liable for manslaughter instead, if he had lost self‐control as a consequence of provocation, and the provocation was ‘enough to make a reasonable man do as he did’.138 Provocation was generally considered to comprise a subjective test—whether the defendant himself actually lost self‐control because of something that counted as provocation—and an objective test—whether a reasonable person, faced with the provocation, would have lost self‐control, and, if so, whether he would have acted as the defendant did. In relation to the objective test, the rather thorny issue for the courts was what characteristics could be accorded to the reasonable person so that the jury would take them into account in making a decision about the defendant's actions.139

(p.257) At one end of the spectrum of possible approaches to this issue lies the House of Lords decision in Smith (Morgan).140 Here, the approach the Court adopted to the question of the characteristics of the reasonable person was expansive and openly moral‐evaluative. In this case, the defendant was charged with killing a friend who he believed had stolen his carpenter's tools. At trial, Smith pleaded a lack of mens rea, provocation, and diminished responsibility. Smith was convicted of murder, and appealed, arguing against the trial judge's direction to the jury that it could not take his severe depressive illness into account when deciding whether an ordinary person would have lost his self‐control. The House of Lords upheld the Court of Appeal decision, in which manslaughter was substituted for murder, and, in doing so, adopted an expansive approach to the scope of the objective component of provocation. The House of Lords held that the objective component of the defence means that ‘the jury can legitimately “give weight to factors personal to the prisoner in considering a plea of provocation” ’.141 This meant that, if it grants provocation, the jury must conclude that ‘the circumstances were such as to make the loss of self‐control sufficiently excusable to reduce the gravity of the offence from murder to manslaughter’.142 In his judgment, Lord Hoffman stated that the jury ‘may think that there was some characteristic of the accused, whether temporary or permanent, which affected the degree of control which society could reasonably have expected of him and which it would be unjust not to take into account. If the jury take this view, they are at liberty to give effect to it.’143 In Lord Hoffman's words, it would be ‘wrong to assume that there is a neat dichotomy between the “ordinary person” contemplated by the law of provocation and the “abnormal person” contemplated by the law of diminished responsibility’.144

At the other end of the spectrum of possible approaches to the scope of provocation, and by contrast with the broad and overtly morally evaluative approach adopted in Smith (Morgan), lies the 2005 Privy Council decision of Attorney‐General v Holley 145 The Privy Council took a narrow approach to the question of which of the defendant's characteristics could be taken into account for the objective part of the provocation defence. The Privy Council concluded that the question for the jury was ‘[w]hether the provocative act or words and the defendant's response met the “ordinary person” standard prescribed by the statute is…not the altogether looser question of whether, having regard to all the circumstances, the jury consider the loss of self‐control was sufficiently excusable’.146 The Privy Council stated that:

[t]he powers of self‐control possessed by ordinary people vary according to their age and, more doubtfully, their sex. These features are to be contrasted with abnormalities, that is, (p.258) features not found in a person having ordinary powers of self‐control. The former are relevant when identifying and applying the objective standard of self‐control, the latter are not.147

As these comments make clear, the Holley decision tightened up the distinction between provocation and diminished responsibility, and in doing so, reinscribed a bright line between ‘normality’ and ‘abnormality’ in criminal law.

These judicial machinations about the characteristics that may be appropriately attributed to the reasonable person for the purposes of provocation reveal that, as Andrew Ashworth suggests, the provocation defence was for defendants who are in a broad sense mentally normal.148 By contrast, the partially exculpatory doctrine of diminished responsibility applies to abnormal defendants. These machinations hint at the profound significance of the normal/abnormal distinction for the criminal law and the disruption that flows from any blurring of the boundaries between these two states.

Notes:

(1) Homicide Act 1957, s 2(1), as amended by Coroners and Justice Act 2009, s 52. A manslaughter conviction attracts sentencing discretion.

(2) See G H Gordon The Criminal Law of Scotland (Edinburgh: W Green, 2000) 455. Although the difference between English and Scots law on the issue of partial insanity had been glossed over following the Articles of Union in 1707, it amounted to a genuine and significant difference in the two legal traditions: N Walker Crime and Insanity in England (Vol 1: The Historical Perspective) (Edinburgh: Edinburgh University Press, 1968) 140–1. In at least formally requiring something like total insanity to acquit a defendant, Scots law paralleled English law: Walker Crime and Insanity in England (Vol 1) 140. See Chapter 5 for a discussion of how ‘total insanity’ as an informal law of insanity might be interpreted in the English context.

(3) L Farmer Criminal Law, Tradition and Legal Order: Crime and the Genius of Scots Law 1747 to the Present (Cambridge: CUP, 1997) 153–4. Significantly, in this era, there was no firm distinction between factors relating to conviction (defences) and those relating to sentence (mitigation). In capital cases, such as murder, conviction meant death unless a prisoner was granted mercy through the royal prerogative: Gordon The Criminal Law of Scotland 453, 458. This led juries to try to encourage the royal prerogative through the practice of issuing ‘verdicts of guilty with a recommendation as to mercy or mitigation of sentence’ to reflect any extenuating circumstances of the defendant: Scottish Law Commission Insanity and Diminished Responsibility (Discussion Paper 122, 2003) para 3.1 and Scottish Law Commission Insanity and Diminished Responsibility (Report 195, 2004) para 3.1. The defendant's abnormal mental state was one such extenuating circumstance.

(4) Gordon The Criminal Law of Scotland 453.

(5) Gordon The Criminal Law of Scotland 453.

(6) Culpable homicide was distinct from manslaughter in English law, which, since the sixteenth century, had denoted killings in the absence of premeditation, such as those committed ‘in the heat of passion.’ See J M Beattie Crime and the Courts in England 1660–1800 (Oxford: OUP, 1986) 79–80 and J M Kaye, ‘The Early History of Murder and Manslaughter’ (1967) 83 Law Quarterly Review 365, 369–70.

(7) Farmer Criminal Law, Tradition and Legal Order 153. Unlike murder, which automatically attracted the death penalty, a conviction for culpable homicide gave the judge discretion in sentencing: Scottish Law Commission Insanity and Diminished Responsibility (Discussion Paper 122, 2003) para 3.1.

(8) Criminal Law, Tradition and Legal Order 154.

(9) Criminal Law, Tradition and Legal Order 154.

(10) Gordon The Criminal Law of Scotland 453.

(11) Farmer Criminal Law, Tradition and Legal Order 154.

(12) See Walker Crime and Insanity in England (Vol 1) 142.

(13) Dingwall (1867) 5 Irv 466.

(14) Dingwall (1867) 5 Irv 466, 479.

(15) Dingwall (1867) 5 Irv 466, 480. The jury returned a verdict of culpable homicide, and Dingwall was sentenced to 10 years’ penal servitude.

(16) McLean (1876) 3 Couper 334. McLean was regarded as an imbecile and had once been a certified lunatic. Theft by housebreaking was a capital charge but one for which the death penalty was no longer considered appropriate: see Gordon The Criminal Law of Scotland 461.

(17) The Criminal Law of Scotland 461.

(18) McLean (1876) 3 Couper 334, 336, extracted in Gordon The Criminal Law of Scotland 461.

(19) As a result, Lord Deas’ direction in Dingwall was ‘less remarkable’ than it would have been in England. See Walker Crime and Insanity in England (Vol 1) 144.

(20) Gordon The Criminal Law of Scotland 453.

(21) The Criminal Law of Scotland 460–1.

(22) The Criminal Law of Scotland 461.

(23) See The Criminal Law of Scotland 461–3 for discussion of these cases.

(24) Dingwall, per Lord Deas, extracted in Gordon The Criminal Law of Scotland 460.

(25) N Lacey ‘Responsibility and Modernity in Criminal Law’ (2001) 9(3) Journal of Political Philosophy 249, 261. For a discussion of change in the concept of ‘dole’ in the Scots law at this time, see Farmer Criminal Law, Tradition and Legal Order 147–60.

(26) Criminal Law, Tradition and Legal Order 157.

(27) Lacey ‘Responsibility and Modernity in Criminal Law’ 266.

(28) ‘Responsibility and Modernity in Criminal Law’ 267–8. For a discussion of the historical development of criminal responsibility practices, see N Lacey ‘Psychologising Jekyll, Demonising Hyde: The Strange Case of Criminal Responsibility’ (2010) 4 Criminal Law and Philosophy 109.

(29) HM Advocate v Savage 1923 SLT 659, 661. The restriction of the Scots defence of diminished responsibility in the first half of the twentieth century has been interpreted as a defensive move on the part of the judiciary. According to Gordon, the scope of the defence was restricted because judges feared that the defence would ‘lead to many murderers escaping their just deserts’ and because some judges believed the doctrine of diminished responsibility was ‘illogical and anomalous’: see Gordon The Criminal Law of Scotland 463.

(30) Scottish Law Commission Insanity and Diminished Responsibility (Report No 195, 2004) para 3.2. In Carraher (Carraher v HM Advocate 1946 JC 108), in which the Savage statement of the law was approved (117), the Court stated that the defence of diminished responsibility was ‘anomalous’ in the Scots law and concluded that it should not be given wider scope than it has already been accorded (119).

(31) Galbraith v HM Advocate (No 2) 2002 JC 1, 8; see also Scottish Law Commission Insanity and Diminished Responsibility (Report 195, 2004) paras 3.3–3.7. The Scottish Law Commission proposed a statutory version of diminished responsibility that was incorporated into the Criminal Justice and Licensing Act 2010. For discussion, see R M Mackay ‘The Coroners and Justice Act 2009—Partial Defences to Murder (2) The New Diminished Responsibility Plea’ [2010] Criminal Law Review 290, 302.

(32) Gordon The Criminal Law of Scotland 465.

(33) See my Chapter 5; see also K J M Smith Lawyers, Legislators and Theorists: Developments in English Criminal Jurisprudence 1800–1957 (Oxford: Clarendon Press, 1998) 223–32; M Wiener Reconstructing the Criminal: Culture, Law and Policy in England, 1830–1914 (Cambridge: CUP, 1990) 269–76. Similarly, the Scots defence did not receive serious attention in the first decades of the twentieth century when, for example, it might have been examined by the Atkin Committee on Insanity and Crime, which reported in 1923. The lack of consideration given to diminished responsibility may have reflected the English commentators’ preoccupation with the M'Naghten Rules in these decades.

(34) For discussion, see Walker Crime and Insanity in England (Vol 1) 147–8.

(35) United Kingdom Royal Commission on Capital Punishment Report (Cmd 8932, 1953) para 413, 403. The Commission justified this awkward conclusion by arguing that, if diminished responsibility was introduced in England, it would have to become part of the general law rather than just operate as a defence to murder. The Commission's terms of reference were restricted to the law of murder, and it did not consider that ‘so radical an amendment to the law of England would be justified for this limited purpose’ (para 413). Rather than adopt diminished responsibility, the Royal Commission recommended (unsuccessfully) that the insanity defence be extended.

(36) See Walker Crime and Insanity in England (Vol 1) 149.

(37) Homicide Act 1957, s 2.

(38) Courts have a range of sentencing options including imprisonment, up to and including life, a hospital order, a probation or supervision order, a suspended sentence, a restriction order and an absolute discharge: see Law Commission for England and Wales Partial Defences to Murder (Law Com 290, 2004) Appendix B, para 22. Of diminished responsibility pleas granted over 1997–2001, about 49 per cent resulted in restriction orders and 46 per cent resulted in prison terms, supervision orders and suspended sentences (para 22).

(39) Even within the bounds of the offence of murder, diminished responsibility is not available as a (partial) defence to a charge of attempted murder: R v Campbell [1997] Crim LR 495. Under the Law Commission's proposals relating to the law of homicide, diminished responsibility would be available only to reduce first degree murder to second degree murder. See A New Homicide Act for England and Wales? (Law Com 177, 2005).

(40) See, for example, K W M Fulford ‘Value, Action, Mental Illness and the Law’ in S Shute, J Gardner and J Horder (eds) Action and Value in the Criminal Law (Oxford: Clarendon Press, 1993) 279–310, 299–300; J E Hall Williams ‘The Homicide Act 1957’ (1957) 20(4) Modern Law Review 381, 383; G Hughes ‘The English Homicide Act of 1957: The Capital Punishment Issues, and Various Reforms in the Law of Murder and Manslaughter’ (1959) 49(6) Journal of Criminal Law, Criminology and Police Science 521, 525–6; S Prevezer ‘The English Homicide Act: A New Attempt to Revise the Law of Murder’ (1957) 57(5) Columbia Law Review 624, 638; R F Sparks ‘ “Diminished Responsibility” in Theory and Practice’ (1964) 27(1) Modern Law Review 9, 31; B Wootton ‘Diminished Responsibility: A Layman's View’ (1960) 76 Law Quarterly Review 224, 227.

(41) Hansard (HC) (1956–57) (Series 5) vol 560, col 1154 (15 November 1956). Although insanity was not amended, it was envisaged that an insanity plea would be less common once diminished responsibility was introduced: Hansard (HC) (Series 5) (1956–57) vol 560, col 1252–3 (15 November 1956).

(42) Smith Lawyers, Legislators and Theorists 329; see also Walker Crime and Insanity in England (Vol 1) 149.

(43) Coroners and Justice Act 2009, s 52, amending Homicide Act 1957, s 2.

(44) Law Commission for England and Wales Murder, Manslaughter, and Infanticide (Law Com No 304, 2006) para 5.107. By this time, criticisms of diminished responsibility were longstanding. Both the Butler Committee and the Criminal Law Revision Committee (CLRC) considered the provision relating to diminished responsibility to be unsatisfactory on the basis of its ambiguous construction: see United Kingdom Report of the Committee on Mentally Abnormal Offenders (Cmnd 6244,1975) (Butler Report) para 19.5; and Criminal Law Revision Committee Fourteenth Report: Offences Against the Person (Cmnd 7844, 1980) paras 91–2 respectively.

(45) Murder, Manslaughter, and Infanticide (Law Com No 304, 2006) para 5.83. At the time of writing, these changes to the law of homicide have not been implemented.

(46) Murder, Manslaughter, and Infanticide (Law Com No 304, 2006) para 5.114.

(47) See Mackay ‘The Coroners and Justice Act 2009—partial defences to murder (2)’.

(48) R v Spriggs [1958] 1 QB 270, 274; R v Byrne [1960] 2 QB 396, 403 per Lord Parker CJ.

(49) These conditions include Asperger's Syndrome (R v Reynolds (Gary) [2004] EWCA Crim 1834), battered women's syndrome (R v Hobson [1998] 1 Cr App R 31), depression (R v Ahluwalia (1993) 96 Cr App R 133), pre‐menstrual tension (R v Graddock [1981] Current L Ybk 476), psychopathy (R v Byrne [1960] 2 QB 396), reactive depression (R v Seers (1984) 79 Cr App R 261; R v Dietschmann [2003] 1 AC 1209), and schizophrenia (R v Weekes [1999] 2 Cr App R 520).

(50) Referred to in R v Byrne [1960] 2 QB 396, 401 per Lord Parker CJ.

(51) R v Byrne [1960] 2 QB 396, 403 per Lord Parker CJ.

(52) R v Byrne [1960] 2 QB 396, 404 per Lord Parker CJ. The effect of the Byrne decision was that the defence of diminished responsibility in English law was wider than its Scots equivalent at the time: Scottish Law Commission Insanity and Diminished Responsibility (Report No 195, 2004) para 3.25. In its recent review of the defence of diminished responsibility, the Scottish Commission took the view that the exclusion of psychopathic personality disorder was too sweeping and recommended that, in a reformulated, statutory defence, diminished responsibility ‘should not be excluded solely by virtue of the fact that at the relevant time the accused had any form of personality disorder’: see Scottish Law Commission Insanity and Diminished Responsibility (Report No 195, 2004) para 3.34.

(53) R v Byrne [1960] 2 QB 396, 404 per Lord Parker CJ.

(54) R v Byrne [1960] 2 QB 396, 404 per Lord Parker CJ.

(55) See Scottish Law Commission Insanity and Diminished Responsibility (Report No 195, 2004) para 2.6 for discussion.

(56) R v Byrne [1960] 2 QB 396, 404 per Lord Parker CJ. In the year after Byrne, in the Court of Criminal Appeal decision of Rose, the trial judge's direction to the effect that ‘abnormality of mind’ was to be understood ‘in terms of the borderline between legal insanity and legal sanity’ was labelled a ‘serious and vital misdirection’: Rose v R [1961] AC 496, 508 per Lord Tucker. However, the Court stated that if ‘insanity is to be taken into consideration, as undoubtedly will usually be the case, the word must be used in its broad, popular sense’ (508). According to the Court in Rose, whether a direction is made using the words ‘borderline’ and ‘insanity’ will depend on the particular case: it will not be ‘helpful’ in all cases (508). Again, in the decision of Seers (R v Seers (1984) 79 Cr App R 261), the Court of Appeal concluded that a judicial direction that ‘abnormality of mind’ required a ‘condition on the borderline of insanity’ was a material misdirection (265). The Court concluded that reference to insanity was merely ‘one way of assisting the jury to determine the degree of impairment of mental responsibility in the appropriate case’ which would not apply in all circumstances (264).

(57) Hansard (HC) (Series 5) (1956–57) vol 560, col 1154 (15 November 1956).

(58) See Chapter 5.

(59) R v Byrne [1960] 2 QB 396, 403 per Lord Parker CJ. Yet, none of the three causes has a defined or agreed psychiatric meaning: S Dell Murder into Manslaughter: The Diminished Responsibility Defence in Practice (Oxford: OUP, 1984) 39; Law Commission for England and Wales Murder, Manslaughter, and Infanticide (Law Com No 304, 2006) para 5.111; R D Mackay ‘Diminished Responsibility and Mentally Disordered Killers’ in A Ashworth and B J Mitchell (eds) Rethinking English Homicide Law (Oxford: OUP, 2000) 62. The causes gradually acquired legal meaning through a thin line of appellate level case law. In 1994, the Court of Appeal heard the case of Sanderson (R v Sanderson (1994) 98 Cr App R 325), in which the cause of Sanderson's ‘abnormality of mind’ was disputed: Sanderson's defence counsel adduced psychiatric evidence that he suffered from paranoid psychosis while the prosecution adduced evidence that Sanderson's paranoia was the result of drug abuse. In allowing Sanderson's appeal on the basis that the trial judge had misled the Court over the aetiology of ‘abnormality of mind’, the Court of Appeal stated obiter that ‘induced by disease or injury’ referred to ‘organic or physical injury or disease of the body, including the brain’ and that ‘any inherent cause’ covered functional mental illness (336 per Lord Roch). In O’Connell (R v O’Connell [1996] EWCA Crim 1552), the defendant had been taking a sleeping drug on prescription. The Court of Appeal stated that the drug's ‘rapid absorption and elimination from the body’ precluded it from grounding an ‘injury’ for the purposes of Section 2, Homicide Act 1957 (extracted in R D Mackay, ‘The Abnormality of Mind Factor in Diminished Responsibility’ [1999] Criminal Law Review 117, 123–4). This reasoning indicated that an ‘injury’ for the purposes of diminished responsibility had to be more than transitory.

(60) As the parliamentary debates at the time diminished responsibility was introduced indicate, they were intended to circumscribe the scope of the otherwise broad phrase, ‘abnormality of mind’. According to the Lord Chancellor, the purpose of the bracketed causes was to ‘limit the generality of the words “abnormality of mind” and to bring the law into line with the Scots doctrine:’ Hansard (HL) (Series 5) vol 202, col 358 (7 March 1957). The bracketed causes were modelled on the definition of ‘mental defectiveness’ in the Mental Deficiency Act 1927, s 1(2). However, as Griew has pointed out, in the Mental Deficiency Act 1927, the causes were not words of limitation but were intended to suggest ‘however arising or caused’. This mismatch between their original purpose and that to which they were put in the 1957 Act leads Griew to label the causes ‘a remarkably inept reconstruction’ of the 1927 Act: E Griew ‘The Future of Diminished Responsibility’ [1988] Criminal Law Review 75, 77.

(61) Law Commission for England and Wales Murder, Manslaughter, and Infanticide (Law Com No 304, 2006) para 5.114.

(62) See Mackay ‘The Coroners and Justice Act 2009—Partial Defences to Murder (2)’. As the Law Commission stated, what matters is the effect of the condition on the individual.

(63) ‘The Coroners and Justice Act 2009—Partial Defences to Murder (2)’ 294–5. Mackay also posits that, given the changes to the defence of provocation (now ‘loss of control’) that were enacted at the same time in the Coroners and Justice Act 2009, it will be more difficult to raise both ‘loss of control’ and diminished responsibility (295).

(64) See R v Sanderson (1994) 98 Cr App R 325. I discuss the significance of moral culpability in relation to intoxication in Chapter 7.

(65) In Dietschmann, the House of Lords held that diminished responsibility is available to an intoxicated defendant only if his or her abnormality played a part in substantially impairing his or her mental responsibility for the killing ‘despite the drink’: R v Dietschmann [2003] 1 AC 1209, 1227 per Lord Hutton.

(66) In Tandy, the Court of Appeal approved the trial judge's direction that the defendant could not avail herself of the defence of diminished responsibility if she had voluntarily had her first drink of the day: R v Tandy [1989] 1 WLR 350, 357.

(67) See R v Stewart [2009] 2 Cr App R 500, 509. See also R v Wood [2009] 1 WLR 496.

(68) The term ‘mental responsibility’ had no antecedents in either English or Scots law and had been the subject of significant criticism. Although the term ‘mental responsibility’ appeared to be a precise and technical component of the defence and, thus, at least partially within the purview of expert witnesses (S C Hayes ‘Diminished Responsibility: The Expert Witness’ Viewpoint’ in S Yeo (ed) Partial Excuses to Murder (Sydney: Federation Press, 1991) 145, 155), as the Butler Committee pointed out, ‘mental responsibility…is either a concept of law or a concept of morality; it is not a clinical fact relating to the defendant’ (Butler Report para 19.5; see also Mackay ‘Diminished Responsibility and Mentally Disordered Killers’ 62; B J Mitchell, ‘Putting Diminished Responsibility Law into Practice: A Forensic Psychiatric Perspective’ (1997) 8(3) Journal of Forensic Psychiatry 620, 621; G Williams Textbook of Criminal Law (London: Stevens, 1978) 624.

(69) R v Byrne [1960] 2 QB 396, 403 per Lord Parker CJ. Mackay posits that this dicta prompted the legislative drafts to prefer the term ‘ability’ to the term ‘capacity’ which had been the wording of the Law Commission's draft. See Mackay ‘The Coroners and Justice Act 2009—Partial Defences to Murder (2)’ 295.

(70) R v Lloyd [1967] 1 QB 175, 178–9 per Edmund Davies J.

(71) This has been pointed out by R M Mackay who notes that in spelling out what abilities need to be impaired, ‘abnormality of mental functioning’ is now narrower than ‘abnormality of mind’: see Mackay ‘The Coroners and Justice Act 2009—Partial Defences to Murder (2)’ 297. The first element—‘to understand the nature of D's conduct’—is similar to the first limb of M'Naghten insanity (296).

(72) As the Court stated in Wood, ‘the culpability of the defendant in diminished responsibility manslaughter may sometimes be reduced almost to extinction, while in others, it may remain very high’: R v Wood [2010] 1 Cr App R (S) 6, 15.

(73) As Alan Norrie argues in relation to s 2(1), ‘while “abnormality of mind” draws upon a psychiatric view of the causes of mental illness, it is hitched to a moral‐legal judgment’ through the requirement of a substantial impairment. See A Norrie Crime, Reason and History: A Critical Introduction to Criminal Law (London: Butterworths, 2001) 183.

(74) Griew ‘The Future of Diminished Responsibility’ 82. Indeed, wording along these lines had been proposed by the Butler Committee and the CLRC. Both Committees had advocated abolition of the mandatory penalty for murder and concluded that, if this reform was enacted, the diminished responsibility defence would be unnecessary. If the mandatory penalty was retained, the Butler Committee proposed reformulating the defence by replacing the reference to ‘abnormality of mind’ with a reference to ‘mental disorder’, as defined in the civil law, and by explicitly directing the jury to determine whether that disorder was such as to be ‘an extenuating circumstance which ought to reduce the offence to manslaughter’ (Butler Report para 19.17). The CLRC considered this formulation to be insufficiently tight and advocated a version that required that the specified ‘mental disorder’ be ‘a substantial enough reason to reduce the offence to manslaughter’ (para 93).

(75) See, for example, K J M Smith and W Wilson, ‘Impaired Voluntariness and Criminal Responsibility: Reworking Hart's Theory of Excuses—the English Judicial Response’ (1993) 13 Oxford Journal of Legal Studies 69, 89; Williams Textbook of Criminal Law 629.

(76) See, for example, Mitchell ‘Putting Diminished Responsibility Law into Practice’ 631–2; W Wilson Criminal Law: Doctrine and Theory (London: Longman, 2003) 247.

(77) R v Walden [1959] 1 WLR 1008, 1012.

(78) Coroners and Justice Act 2009, s 52(1B), amending Homicide Act 1957, s 2.

(79) Law Commission for England and Wales Murder, Manslaughter, and Infanticide (Law Com No 304, 2006) para 5.124; see also Law Commission for England and Wales Partial Defences to Murder (Law Com No 290, 2004) para 5.95). According to the Commission, this would ensure an ‘appropriate connection’ between the abnormality and the killing, but leaves open the possibility that other factors (such as provocation) may also have been operative at the time the killing occurred (Murder, Manslaughter, and Infanticide para 5.124).

(80) R M Mackay queries whether this requirement will make diminished responsibility harder to satisfy than insanity, which has no such limitation: see Mackay ‘The Coroners and Justice Act 2009—Partial Defences to Murder (2)’ 300.

(81) The Judicial Studies Board specimen direction on diminished responsibility made reference to the caused nature of the defendant's conduct. See for discussion, R v Ramchurn [2010] 2 Cr App R 3. See also Law Commission for England and Wales Murder, Manslaughter, and Infanticide (Law Com No 304, 2006) para 5.122; J Horder Excusing Crime (Oxford: OUP, 2004) 155. In R v Egan [1992] 4 All ER 470, the Court of Appeal denied diminished responsibility to an intoxicated defendant on the basis that it was the consumption of alcohol, rather than internal abnormality, which caused him to kill (479). The decision in Egan was disapproved by the House of Lords in Dietschmann (R v Dietschmann [2003] 1 AC 1209, 1225). In Dietschmann, the House of Lords rejected the idea that a defendant's ‘abnormality of mind’ must be the sole cause of the killing, interpreting the defence of diminished responsibility to require that it must be one although not the sole cause for the defendant's conduct (1217).

(82) See P Arenella ‘The Diminished Capacity and Diminished Responsibility Defenses: Two Children of a Doomed Marriage’ (1977) 77(6) Columbia Law Review 827, 828–9 and S J Morse ‘Diminished Capacity’ in S Shute, J Gardner and J Horder (eds) Action and Value in Criminal Law (Oxford: Clarendon Press, 1993) 239, 240–1 for discussion. However, this type of connection between ‘abnormality of mind’ and the defendant's homicidal conduct was specifically disallowed on the face of both the 2009 and the 1957 versions of diminished responsibility in England and Wales: because diminished responsibility is constructed such that a diminished defendant would otherwise be liable for murder, the doctrine comes into effect, at least in principle, only once the mens rea and actus reus of murder have been proved or admitted.

(83) M S Moore ‘Causation and the Excuses’ (1985) 73 California Law Review 1091, 1148.

(84) G R Sullivan ‘Intoxicants and Diminished Responsibility’ [1994] Criminal Law Review 152, 160.

(85) R v Erskine; R v Williams [2010] 1 WLR 183, 201, regarding Criminal Appeal Act 1968, s 23.

(86) R v Diamond [2008] EWCA Crim 923, [23]. See also R v Neaven [2007] 2 All ER 891.

(87) R v Erskine; R v Williams [2010] 1 WLR 183, 207. The Court admitted the fresh evidence, and substituted a conviction of manslaughter on the grounds of diminished responsibility.

(88) R v Latus [2006] EWCA Crim 3187. See also R v Shickle [2005] EWCA Crim 1881, in which the Court concluded that there was ‘no reasonable explanation for failing to adduce the evidence of diminished responsibility at the trial’ ([64]) and declined to grant the appeal. Concern with these kinds of cases was perhaps behind the Criminal Cases Review Commission (CCRC) submission to the Law Commission, in which they called for the abolition of diminished responsibility (Murder, Manslaughter, and Infanticide (Law Com No 304, 2006) para 5.91).

(89) Criminal Law Revision Committee Fourteenth Report: Offences Against the Person (Cmnd 7844, 1980) para 95. The procedural rule that only the defence may raise diminished responsibility parallels the rule relating to raising automatism, and both rules may be interpreted as products of presumptions made in the criminal law. In relation to automatism, the presumption is the ‘presumption of mental capacity’ ensuring that an act can be presumed to be voluntary unless there is evidence to rebut this presumption.

(90) R v Campbell (1987) 84 Cr App R 255; see also Mackay ‘Diminished Responsibility and Mentally Disordered Killers’ 77. Unlike the notable case of infanticide, which is a discrete category of homicide, it is not possible to be charged with ‘manslaughter by reason of diminished responsibility’. Both the Butler Report and the CLRC Report on Offences Against the Person proposed that, subject to the defendant's consent and where there was clear evidence indicating that a defence can be made out, the prosecution should be able to indict the defendant for manslaughter (Butler Report para 19.19; CLRC Fourteenth Report para 95–6). In formulating this proposal, both the Butler Committee and the CLRC focused on the practical advantages of pleading diminished responsibility, including that the indictment accurately reflected the trial outcome; that a trial for murder would not further damage the accused's mental state; and that decision‐making would not be left to the jury when the Crown's own evidence pointed to diminished responsibility (Butler Report para 19.19; CLRC Fourteenth Report para 95). Although these proposals have not been implemented, the effect of the change in the way in which diminished responsibility is decided—to allow the prosecution to accept a plea of diminished responsibility in cases where the medical evidence is unequivocal—is such that the concerns of the Butler Committee and the CLRC have been addressed without reform to the way in which offences are charged. The status quo was noted with approval by the Law Commission: Murder, Manslaughter, and Infanticide (Law Com No 304, 2006) paras 5.102–5.106.

(91) Criminal Procedure (Insanity) Act 1964, s 6.

(92) R v Campbell (1987) 84 Cr App R 255, 260 per Lord Kennedy CJ; see also R v Kooken (1982) 74 Cr App R 30, 34. The Court in Campbell reasoned that because s 2(1) of the Homicide Act 1957 provides that ‘it shall be for the defence to prove’ diminished responsibility, and because ‘the judge's knowledge of the evidence available in relation to the issue of diminished responsibility will inevitably be limited’, it should be left to defence counsel to choose to run the defence (at 259–60). This wording is unchanged by the 2009 Act and thus diminished responsibility continues to be an ‘optional defence’.

(93) Regarding the burden of proof, see Homicide Act 1957, s 2; this section of the 1957 Act was unchanged by the 2009 amendments. In relation to the standard of proof, see R v Dunbar [1958] 1 QB 1 at 11–12, in which the Scots law was taken into consideration. If the prosecution adduces evidence of diminished responsibility (because the defence has raised insanity), the standard of proof is beyond all reasonable doubt: see R v Grant [1960] Crim LR 424. In relation to the standard of proof, diminished responsibility differed from the now‐defunct provocation defence: in raising provocation, the defence bore only an evidential burden of proof: Attorney‐General for Jersey v Holley [2005] 2 AC 580, 612. It has been argued that different standards and burdens of proof for provocation/now ‘loss of control’ and diminished responsibility caused jurors confusion as the defences were able to be run simultaneously (see, for example, A P Simester et al Simester and Sullivan's Criminal Law: Theory and Doctrine (Oxford: Hart, 2010) 401–2, 715–16). Although several law reform bodies have concluded that the burden of proof for diminished responsibility should be an evidentiary one as was the case with provocation (Butler Report para 19.18; CLRC Fourteenth Report para 94), the Law Commission expressly recommended against changes to the burden of proof in its report on partial defences (Partial Defences to Murder (Law Com No 290, 2004), para 5.91) and briefly affirmed the status quo in its report on reform to the law of homicide (Murder, Manslaughter, and Infanticide para 5.105). Given the parallel with the law of insanity, justifications for the burden and standard of proof for diminished responsibility echo those offered for the reverse burden in relation to insanity. Thus, one explanation proffered is that the knowledge required to make out the defence of diminished responsibility is uniquely within the province of the accused (see, for example, P W Ferguson, ‘Reverse Burdens of Proof’ (2004) 22 Scots Law Times 133, 138; Law Commission for England and Wales Partial Defences to Murder para 5.90). This justification is based on the assumed difficulty of assessing abnormal mental states for the purposes of the defence, and its popularity helps to account for the prominence of expert evidence in diminished responsibility cases. See my Chapter 6 for discussion of the issue of assessing abnormal mental states in the context of insanity.

(94) See Mackay ‘Diminished Responsibility and Mentally Disordered Killers’ 62. Perhaps the most well‐known instance of a judge rejecting an agreement to accept a plea to manslaughter on the basis of diminished responsibility occurred in the case of the ‘Yorkshire Ripper’. See R v Sutcliffe The Times, 30 April 1981.

(95) R v Cox [1968] 1 WLR 308, 311. The Cox Court was motivated by the practical considerations of the time and monetary cost of a trial, as well as the ‘anxiety and uncertainty’ defendants face while murder trials take place. The Court in Cox offered no further explanation for treating diminished responsibility differently from insanity, which must go to the jury: see Bratty v Attorney‐General for Northern Ireland [1963] AC 386.

(96) Law Commission for England and Wales Murder, Manslaughter, and Infanticide (Law Com No 304, 2006) para 5.96; Law Commission for England and Wales Partial Defences to Murder (Law Com No 290, 2004) Appendix B, para 20; Mackay ‘Diminished Responsibility and Mentally Disordered Killers’ 61. Under these conditions, it is possible that some diminished responsibility claims which are accepted by the prosecution would have been rejected by a jury (Mackay ‘Diminished Responsibility and Mentally Disordered Killers’ 63), effectively enlarging the scope of the plea. In his recent study for the Law Commission, Mackay found that, of the cases in which diminished responsibility was raised, the prosecution accepted a plea in 77 per cent of the cases (Partial Defences to Murder (Law Com No 290, 2004) Appendix B para 20). Of the cases in which the plea was contested by the prosecution (23 per cent), only 22 per cent were successful (Appendix B para 21).

(97) R v Matheson [1958] 1 WLR 474. In interpreting the Homicide Act 1957 to require that a jury evaluate the claim to the defence, the Court in Matheson simply stated that the issue ‘must be left to the jury, just as the issue must be if the defence is insanity’ (R v Matheson [1958] 1 WLR 474, 480 per Lord Goddard).

(98) R v Matheson [1958] 1 WLR 474, 480.

(99) R v Byrne [1960] 2 QB 396, 403–4; see also R v Jennion [1962] 1 WLR 317, 322; R v Tandy [1989] 1 WLR 350, 356; R v Khan (Dawood) [2010] 1 Cr App R 74, 86.

(100) R v Byrne [1960] 2 QB 396, 403, 404.

(101) Reflecting the contested nature of pleas coming before juries, Mackay's recent research indicated that only 22 per cent of the cases in which the defence was contested by the prosecution were successful: Law Commission for England and Wales Partial Defences to Murder (Law Com No 290, 2004) Appendix B para 21; see also Mackay ‘Diminished Responsibility and Mentally Disordered Killers’ 62.

(102) Law Commission for England and Wales Murder, Manslaughter, and Infanticide (Law Com No 304, 2006) para 5.111; see also Law Commission for England and Wales Partial Defences to Murder (Law Com No 290, 2004) Appendix B para 28). In relation to the former version of diminished responsibility, the Court of Appeal in R v Dix (1982) 74 Cr App R 306 stated that expert evidence about the defendant's ‘abnormality of mind’, its causes, and the question of whether the defendant's ‘mental responsibility’ was ‘substantially impaired’ was ‘essential’ to a diminished responsibility defence (R v Dix (1982) 74 Cr App R 306, 311 per Lord Shaw). According to the Dix Court, although Section 2(1) does not require that medical evidence is adduced in support of a defence of diminished responsibility, ‘it makes it a practical necessity if the defence is to begin to run at all’ (R v Dix (1982) 74 Cr App R 306, 311 per Lord Shaw).

(103) In the study commissioned by the Law Commission, Mackay found a total of 366 expert reports in the court files of 157 diminished responsibility cases (Law Commission for England and Wales Partial Defences to Murder (Law Com No 290, 2004) Appendix B para 24). Mackay found that these reports were commissioned in approximately equal numbers by the prosecution and defence (Appendix B para 25). The study found that the primary diagnoses given to defendants seeking to rely on diminished responsibility were depression, schizophrenia, personality disorder, and psychosis, in descending order of popularity (Appendix B para 26). Taking into account the kind of diagnoses identified in these reports, the Law Commission concluded that the defence succeeds where there is ‘a clear psychosis’ or, ‘in other cases (such as depression), its success is related to whether there is an established prior medical condition and its severity’ (Partial Defences to Murder para 5.84).

(104) In its report, the Law Commission recorded as one of the virtues of its proposal that it makes the relationship between the role of the expert and the role of the jury ‘clearer’ (Partial Defences to Murder para 5.117). Mackay's study found that expert witnesses were commenting on the issue of ‘substantial impairment of mental responsibility’ in 69 per cent of cases (Law Commission for England and Wales Partial Defences to Murder (Law Com No 290, 2004) Appendix B para 32; see also Law Commission for England and Wales Murder, Manslaughter, and Infanticide (Law Com No 304, 2006) para 5.118; see also Griew ‘The Future of Diminished Responsibility’ 82; Mitchell ‘Putting Diminished Responsibility Law into Practice’ 622. Some writers have suggested that psychiatrists and other experts are willing participants in this intrusion into the jury role (see, for example, Griew ‘The Future of Diminished Responsibility’ 84). However, the Royal College of Psychiatrists’ submission to the Law Commission expressed support for the legal view that the expert should not comment on the ‘ultimate issue’: Murder, Manslaughter, and Infanticide (Law Com No 304, 2006) paras 5.117–5.120 for discussion.

(105) Griew suggests that reliance on expert psychiatric and psychological evidence is a device for stretching the scope of s 2(1) in practice: ‘The Future of Diminished Responsibility’ 84. Mackay suggests that judges admit expert psychiatric and psychological evidence on the question of whether the defendant's ‘mental responsibility’ was ‘substantially impaired’ in order to assist the jury in the difficult task of assessing the genuine capacities and choices of the defendant: R D Mackay Mental Condition Defences in the Criminal Law (Oxford: Clarendon Press, 1995) 192.

(106) Norrie argues that ‘psychiatric testimony operates to stretch irresponsibility beyond the narrow bounds of the legal test’ and thus operates as a ‘safety valve’ for the law—it provides the means of introducing a satisfactorily circumscribed compassion into the legal rules’ of insanity and diminished responsibility: Crime, Reason and History 190–1.

(107) A P Simester et al Simester and Sullivan's Criminal Law 719; see also W Wilson Criminal Law: Doctrine and Theory (London: Longman, 2003) 250. Simester et al argue that, once given diagnostic labels (such as ‘reactive depression’), conditions arising from external circumstances can be brought within diminished responsibility. One species of such homicides is ‘mercy killings’, where those who kill are believed to have been motivated by laudable considerations such as ending the suffering of a loved one who is ill. In one empirical study, Mackay identified 22 homicides described as ‘mercy killings’ between 1982–1991 in England and Wales: of these, only one murder verdict was returned: ‘Diminished Responsibility and Mentally Disordered Killers’ 79. In another study, Mackay found that each of the three defendants in homicides described as ‘mercy killings’ was successful in arguing diminished responsibility: Law Commission for England and Wales Partial Defences to Murder (Law Com No 290, 2004) para 5.40. The Law Commission sounded a note of caution in relation to these sorts of cases, stating that ‘where there are “deserving cases” or non‐medical grounds such as “mercy killings”, they need to be addressed honestly and openly rather than disguised as cases or issues of diminished responsibility: Partial Defences to Murder (Law Com No 290, 2004) para 5.94.

(108) See T Ward ‘Observers, Advisors, or Authorities? Experts, Juries and Criminal Responsibility in Historical Perspective’ (2001) 12 Journal of Forensic Psychiatry 105.

(109) These formal qualities are, on the one hand, that ‘madness’ is constructed as it is dispositional, and, on the other hand, that it can be ‘read off’ conduct by different participants in the criminal justice process. See further my ‘manifest madness’ analysis in Chapter 3.

(110) Law Commission for England and Wales Partial Defences to Murder (Law Com No 290, 2004) para 5.74.

(111) Partial Defences to Murder (Law Com No 290, 2004) para 5.33.

(112) Aileen McColgan finds that women indicted for murder over 1996–97 were about twice as likely as men to be convicted of manslaughter under s 2(1): ‘General Defences’ in D Nicolson and L Bibbings (eds) Feminist Perspectives on Criminal Law (London: Cavendish Press, 2000) 137, 140; see also Law Commission for England and Wales Partial Defences to Murder (Law Com No 290, 2004) Appendix B para 8.

(113) Partial Defences to Murder para 5.36 and Appendix B para 21.

(114) Partial Defences to Murder paras 5.34, 5.39 and Appendix B para 21.

(115) Partial Defences to Murder Appendix B para 23.

(116) I take this up in my discussion of the law on infanticide: see Chapter 8.

(117) In her study of the operation of the defence in the first two years of its life, Barbara Wootton finds that a diminished responsibility plea was accepted in more than two thirds of cases where the defence was argued (Wootton ‘Diminished Responsibility: A Layman's View’ 225). However, by 1986–88, the success rate of the defence had dropped to 42 per cent (Mackay Mental Condition Defences 181). The numbers of successful pleas has declined further in the years since then. Mackay found that there were 78 cases in which the diminished responsibility defence was successful in 1992 but only 49 in 1996 (Mackay ‘The Abnormality of Mind Factor in Diminished Responsibility’ 117). In a recent study commissioned by the Law Commission for England and Wales, Mackay found that between 1997 and 2001, there were a total of 171 successful pleas of diminished responsibility (Partial Defences to Murder (Law Com No 290, 2004) Appendix B para 6).

(118) Partial Defences to Murder Appendix B para 5. The introduction of the defence of diminished responsibility has been accompanied by a decline in the use of insanity (and unfitness to plead) in murder trials (Mackay ‘Diminished Responsibility and Mentally Disordered Killers’ 59 and Mackay Mental Condition Defences 181; Walker Crime and Insanity in England (Vol 1) 158), which suggests that diminished responsibility has been raised by defendants who previously would have relied on the insanity defence (Mackay ‘Diminished Responsibility and Mentally Disordered Killers’ 56; Sparks ‘ “Diminished Responsibility” in Theory and Practice’ 32).

(119) As reflected in the House of Lords decision of R v Smith (Morgan) [2001] 1 Cr App R 3, under this approach, the objective part of the provocation test was interpreted such that particular characteristics of the defendant (including, in that case, depression) could be attributed to the reasonable man for the purposes of determining the degree of self‐control that could be expected of him. This approach to provocation was disapproved in Attorney‐General for Jersey v Holley [2005] 2 AC 580 in 2005. The Privy Council held that the only characteristics of the defendant that were relevant to the objective test are his or her age and sex (Attorney‐General for Jersey v Holley [2005] 2 AC 580, 591 per Lord Nicholls). The pre‐Holley approach to provocation that encompassed abnormal mental states may have meant that some matters in which diminished responsibility would have been raised were instead decided via provocation.

(120) There was some evidence of these concerns in the empirical survey of popular attitudes to partial defences to murder, conducted by Barry Mitchell, and commissioned for the Law Commission's 2004 report. Mitchell concluded that survey participants accepted expert evidence when it was ‘clear and unequivocal’ but also expressed ‘some cynicism or skepticism about the reliability of psychiatric evidence’ in relation to diminished responsibility (Law Commission for England and Wales Partial Defences to Murder (Law Com No 290, 2004) Appendix C para 77).

(121) See Chapter 6 for a discussion in the context of insanity.

(122) Griew ‘The Future of Diminished Responsibility’ 81–2.

(123) Sparks ‘“Diminished Responsibility” in Theory and Practice’ 18.

(124) ‘ “Diminished Responsibility” in Theory and Practice’ 16.

(125) See, for example, Griew ‘The Future of Diminished Responsibility’ 82; Horder Excusing Crime 155; Smith and Wilson, ‘Impaired Voluntariness and Criminal Responsibility’ 89. In speculating about how the defence might work in practice, Griew posits that, in deciding whether to grant a defence of diminished responsibility, the jury may ‘set the defendant's abnormality and its effects upon him against the character of the offence’: ‘The Future of Diminished Responsibility’ 83.

(126) See, eg, Sparks ‘ “Diminished Responsibility” in Theory and Practice’ 17.

(127) See, eg, Arenella ‘The Diminished Capacity and Diminished Responsibility Defenses’ 863–5.

(128) See, eg, Griew ‘The Future of Diminished Responsibility’ 87; N Lacey ‘Partial Defences to Homicide: Questions of Power and Principle in Imperfect and Less Imperfect Worlds’ in A Ashworth and B J Mitchell (eds) Rethinking English Homicide Law (Oxford: OUP, 2000) 111; Mackay ‘Diminished Responsibility and Mentally Disordered Killers’ 60 and Mackay Mental Condition Defences 185.

(129) H Fingarette ‘Diminished Mental Capacity as a Criminal Defence’ (1974) 37(3) Modern Law Review 264, 275.

(130) J Dressler ‘Reaffirming the Moral Legitimacy of the Doctrine of Diminished Capacity: A Brief Reply to Professor Morse’ (1984) 75(3) Journal of Criminal Law and Criminology 953, 960; R G Meakin ‘Diminished Responsibility: Some Arguments for a General Defence’ (1988) 52 Journal of Criminal Law 406, 407.

(131) M Wasik ‘Partial Excuses in Criminal Law’ (1982) 45(5) Modern Law Review 516, 524–5.

(132) ‘Partial Excuses in Criminal Law’ 524.

(133) Fingarette ‘Diminished Mental Capacity as a Criminal Defence’ 274.

(134) The mandatory penalty is often invoked to explain the ongoing existence of diminished responsibility. See, for example, H Allen Justice Unbalanced: Gender, Psychiatry and Judicial Decisions (Milton Keynes: Open University Press, 1987) 117; Gordon The Criminal Law of Scotland 452. By corollary, several commentators have suggested that the diminished responsibility defence would be unnecessary if the mandatory penalty for murder was abolished (see, for example, Walker Crime and Insanity in England (Vol 1) 162; Law Commission for England and Wales Partial Defences to Murder (Law Com No 290, 2004) para 5.11).

(135) According to some writers, like the former partial defence of provocation, diminished responsibility owes its existence not so much to the mandatory penalty but to the structure of the law of homicide. According to this argument, because murder and manslaughter prohibit the same kind of conduct (killing), partial excuses are necessary to distinguish among defendants who fall within ‘broad bands of culpability’: Wasik ‘Partial Excuses in Criminal Law’ 530. As Wasik argues, partial defences accommodate pressure for the recognition of moral and legal subdivision in the law of homicide (‘Partial Excuses in Criminal Law’ 530).

(136) Coroners and Justice Act 2009, ss 54–6, amending Homicide Act 1957, s 3. The new Act replaced provocation with a partial defence to murder which requires that the defendant killed as a result of a ‘loss of self‐control’ (which had a ‘qualifying trigger’) and a person of the defendant's same sex and age, ‘with a normal degree of tolerance and self restraint’, and in the circumstances of the defendant might have reacted in the same way. See A Norrie ‘The Coroners and Justice Act 2009—Partial Defences to Murder (1) Loss of Control’ [2010] Criminal Law Review 275 for discussion.

(137) The courts’ answer to this question has varied according to whether the characteristic is alleged to have affected the gravity of the provocation or to have rendered the defendant less able to control him or herself (ie more provokable). In relation to the former, all kinds of characteristics including discreditable ones, may be taken into account if they become the subject of the taunt to which the defendant reacts. In relation to the latter, the approach has been more restrictive, with the reasonable person standard used to exclude ‘unusual’ people from the protection of the defence. In an early decision on this part of the reasonable person test, DPP v Camplin [1978] AC 705, the House of Lords held that, for the purposes of determining whether a reasonable person would have done as the defendant did, the reasonable person is to be accorded only the defendant's age and sex. See now Coroners and Justice Act 2009, s 54(1)(c), abolishing provocation as set down in Homicide Act 1957, s 3.

(138) See Homicide Act 1957, s 3.

(139) See further A P Simester et al Simester and Sullivan's Criminal Law 381.

(140) R v Smith (Morgan) [2001] 1 Cr App R 31.

(141) R v Smith (Morgan) [2001] 1 Cr App R 31, 38 per Lord Slynn (extracting words of the Royal Commission on Capital Punishment Report 1953).

(142) R v Smith (Morgan) [2001] 1 Cr App R 31, 58.

(143) R v Smith (Morgan) [2001] 1 Cr App R 31, 58.

(144) R v Smith (Morgan) [2001] 1 Cr App R 31, 52.

(145) Attorney‐General v Holley [2005] 2 AC 580.

(146) Attorney‐General v Holley [2005] 2 AC 580, 593.

(147) Attorney‐General v Holley [2005] 2 AC 580, 591. In R v James; R v Karimi [2006] 1 Cr App R 440, the Court of Appeal held that Holley, rather than Smith (Morgan), represented the English law.

(148) A Ashworth ‘The Doctrine of Provocation’ [1976] Criminal Law Journal 292, 312. Ashworth acknowledges, however, that it may not be the case that the law actually operates with such a clear distinction between diminished responsibility and provocation (314).