Is the Defence of Diminished Responsibility fairly constructed under English Law?

By | October 11, 2021
Defence of Diminished Responsibility

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This article titled ‘Is the Defence of Diminished Responsibility fairly constructed under English Law?’ is written by Kshitij Pal and discusses the concept of diminished responsibility under English Law.

I. Introduction

The statutory concept of diminished responsibility has been an easy target for any critic since its establishment in 1957 under section 2 of the Homicide Act.[1] Calls for change have reverberated for more than half a century, with numerous versions originating from a range of sources, including the Butler Report,[2] the Criminal Law Revision Committee, the Law Commission, and a number of academic commentators.

The partial defence was the most recent emphasis of the government’s “protracted”[3] examination of murder law, which came to a climax in November 2009,[4] when the partial defence became the most recent focus of the study. As a result, the meaning of diminished responsibility in England and Wales has been drastically changed, thanks to the unusual framework of the Coroners and Justice Act 2009.[5]

Despite the fact that the Act’s primary goal is to reform coroner law, section 52 provides new terminology for diminished responsibility that, as we’ll see, differs dramatically from the prior legislation.

The Act’s objective, in the context of criminal law, is to modernize the latter in order to “better its clarity, fairness, and efficacy.”[6]

II. Content and Structure of Criminal Justice under the Act

“In 2003, the Home Secretary invited the Law Commission to look into and report on the law and practice of partial murder defences in the context of domestic abuse.[7] As a result, in 2004, the Law Commission issued its report on Partial Defences to Murder.[8] The Commission’s key recommendation on diminished responsibility was that the definition under section 2(1) remain maintained as long as the law of murder remained unchanged, with a mandatory sentence of life imprisonment for those convicted.[9]

The Commission found that the definition did not cause injustice and that it would be more appropriate to postpone diminished responsibility reform until the Government assigns it the task of conducting a comprehensive review of all murder laws, at which time partial defences could be examined from the ground up.[10]

In a good step, the government did just that, culminating in the Law Commission issuing a report on murder, manslaughter, and infanticide in 2006.[11] The finding suggests repealing the 1957 Homicide Act and replacing it with a new Homicide Act for England and Wales, which would for the first time define comprehensive and uniform definitions of homicide offences and partial defences.[12]

The Law Commission recommended a ladder method to restructure homicide offences, with a hierarchy of graduated violations happening under the umbrella of homicide, which would indicate the gravity of the offences.[13] As a consequence, the offences would be split into two categories of murder, with only first-degree murder receiving a required penalty.[14]

The Law Commission would keep reduced responsibility (together with gross provocation or fear of severe violence and participation in a suicide pact) as a partial defence, with a successful plea reducing first-degree murder to second-degree murder.[15] It was suggested that the substantive legal definition of reduced liability be updated so that it is clearer and more adapted to accommodate changes in expert diagnostic practice.[16] It’s controversial whether or not the government’s guiding principles apply to the legal structure.

If one believes that they do, the next question is whether they have been taken into account adequately in this situation. The Law Commission’s broader contextual recommendations, as well as how the criminal law interacts with offenders with mental disorders on a broad scale, are ignored in a piecemeal approach to reforming the law of homicide by merely addressing partial defences in an Act dedicated to a variety of issues.

Despite being a positive beginning, it needs to be seen whether reformulating the defences in isolation causes more harm than benefit; especially in light of the fact that the original definition of diminished responsibility, despite its ambiguous and archaic nature, has worked well in practice.[17]

III. The Substantive Content of Section 52 of the Act

Where a person murders or is a party to the death of another, he shall not be guilty of murder if he was suffering from such abnormality of mind (whether originating from a state of halted or retarded mental development or any inherent causes or caused by sickness or injury) that considerably affected his mental responsibility for his acts or omissions in doing or being a party to the killing. In order to bring a valid plea of reduced culpability under the old concept, there were two essential criteria.

In the first instance, the accused must have had a mental abnormality, and in the second instance, that condition must have significantly harmed his mental responsibility for the murder. Courts have construed the defence to include a wide range of mental illnesses,[18] such as psychopathy, volitional insanity, and alcoholism.[19] The mercy-killer was likewise included in the scope of the defence.

The next part, which naturally overlaps principles, discusses the many objections of decreased accountability under the categories of clarity and justice. Effectiveness is also taken into account, although only to a lesser amount. The discussion is not limited to these topics, but their inclusion helps to keep the government’s objectives in mind while examining the critiques of the previous legislation.

IV. Abnormality of mental functioning arising from a ‘Recognised Medical Condition’

Since the phrase “abnormality of mind” and the bracketed main causative reasons that follow it are not psychiatric terminology,[20] the courts have had to establish their meaning from case to case. It’s conceivable, therefore, that this definition has resulted in a lack of legal consistency, a complaint that the Government has attempted to address with the more careful language of section 52. Nonetheless, the bracketed causes have permitted flexible interpretation in practice, despite being obsolete, seldom used, and without an agreed-upon psychiatric meaning.[21]

Despite the fact that the language did not create any unfairness, the Law Commission expressed worry that diagnostic practice in reduced responsibility cases has long ago progressed beyond the identification of the restricted spectrum of causes of a mental illness, a concern shared by the Government.[22]

The wording “abnormality of mental functioning” has been substituted for the rather vague “abnormality of mind” in section 52. The bracketed words have been deleted, and the phrase recognized medical condition has been substituted. As a result, the law is no longer constrained by the predefined set of circumstances that must result in an abnormality of mental functioning. Rather, the question is whether the anomaly was caused by a known medical disease.

The Royal College of Psychiatrists has backed the proposal, stating that “the inclusion of such a limitation… will guarantee that any such defence is founded in legitimate medical diagnosis.” As a result, the law is no longer constrained by the predefined set of circumstances that must result in an abnormality of mental functioning. Rather, the question is whether the anomaly was caused by a known medical disease. The Royal College of Psychiatrists has backed the proposal, stating that “the inclusion of such a limitation… will guarantee that any such defence is founded in legitimate medical diagnosis.”[23]

It would also encourage reference within expert evidence to diagnosis in terms of one or two of the accepted internationally classificatory systems of mental conditions (WHO ICD10 and AMA DSM) without explicitly writing those systems into the legislation . . . Such an approach would also avoid individual doctors offering idiosyncratic ‘diagnoses’ as the basis for a plea of diminished responsibility[24].

Thus, in practice, it is likely that psychiatric classificatory systems will play a more central role in establishing the existence of a recognised medical condition resulting in an abnormality of mental functioning. Of course, most diagnoses by experts under the original definition would have had some recognised medical basis. The new wording, however, makes this requirement essential, so in that respect, it clarifies the law.

But this change in definition may have more far-reaching consequences than initially anticipated. Accepting that it has not yet been interpreted by the courts, the term ‘recognised medical condition, as it stands, has the effect of narrowing the defence of diminished responsibility by excluding those disorders which may no longer or may not yet be accepted internationally as ‘medical conditions’.

V. Conclusion

Section 52 goes some way towards clarifying the law of diminished responsibility. Most significantly, it defines what amounts to mental responsibility and provides a medical basis for diagnoses under the section, with the introduction of the recognised medical condition criterion.

However, unforeseen consequences may lead to unfairness for certain categories of defendants, in light of the narrowing effect of the refined definition.

Fairness on a broader scale has also been considered. Deeper issues that go to the heart of the defence itself both in practice (procedural fairness) and in theory (fair labelling) need further consideration. It is unfortunate that the opportunity was not taken at this time to reassess the concept and application of diminished responsibility as a defence to murder from first principles, something which fell beyond the remit even of the Law Commission.

From a structural perspective, this paper identifies the segmented means of updating both the law of homicide and the law as it relates to offenders with a mental disorder. Section 52 is adrift in an Act dedicated to a conglomeration of issues and suffers for it. It is regrettable that the opportunity to review the law in this area in its entirety was not availed of, particularly as a reformulation of the original definition, although required, is not critical at this time.


[1] P. R. Glazebrook, ‘Dealing with Mentally Disordered Offenders’ (1976) 35 Cambridge.

[2] For example, Sparks opines that: ‘. . . it seems clear that, on balance, the practical effects of section 2 to date have been unsatisfactory in certain respects; that these ill effects would have been avoided if the law had not been passed in its present form; and that there is no way of insuring that they will be avoided in future, so long as the law remains as it now is,’ R. Sparks, ‘Diminished Responsibility in Theory and Practice’ (1964) 27 MLR.

[3] Criminal Law Revision Committee: Offences Against the Person.

[4] Criminal Law Revision Committee: Offences Against the Person, Four

[5] Partial Defences to Murder; Law Commission Report No 290 (2004) and Murder, Manslaughter and Infanticide, Law Commission Report.

[6] 829, 829. 8 The Act received Royal Assent on 12 November 2UUV. lhe Commencement Uate tor s dz was 4 October 2010 (Commencement No.4). For a detailed review of the wording of the definition, see R. D. Mackay, ‘The Coroners and Justice Act 2009 – Partial Defences to Murder (2) The New Diminished Responsibility Plea [2010] Crim L R 290

[7] Coroners and Justice Act 2009, Explanatory Notes at [14]. This echoes the Law Commissions emphasis on bringing order, fairness and clarity to the law of homicide’, Law Commission Report (2006), n 5 above at [2.4].

[8] A. Ashworth, ‘Principles, Pragmatism and the Law Commission’s Recommendations on Homicide Law Reform [2007] Crim L R 333, 344.

[9] Law Commission Report (2004), n 5 above. For discussion see Editorial, ‘Partial Defences to Mur- der’ [2004] Crim L R 1.

[10] Law Commission Report (2004), n 5 above. For discussion see Editorial, ‘Partial Defences to Mur- der’ [2004] Crim L R 1.

[11] Law Commission Report (2004), n 5 above. For discussion see Editorial, ‘Partial Defences to Mur- der’ [2004] Crim L R 1.

[12] It is only in the context of a full review that the Commission proposed a definition of diminished responsibility based on its prior consultation process. The Commission’s proposal received much support from academic commentators. For example, see Editorial, Adjusting the Boundaries of Murder: Partial Defences and Complicity’ [20081 11 Crim L R 829.

[13] Law Commission Report (2006), n 5 above. For commentary on the Law Commission’s preceding Consultation Paper, A New Homicide Act for England and Wales?, Consultation Paper No 177 (2005), see: Editorial, ‘Reviewing the Law of Homicide’ [2006] Crim L R 187; W Wilson, ‘The Structure of Criminal Homicide’ [2006] Crim L R 471; A. Norrie, ‘Between Orthodox Subjectivism and Moral Contextualism: Intention and the Consultation Paper’ [2006] Crim L R 486; O Quick and C Wells, ‘Getting Tough with Defences’ [2006] Crim L R 514; V Tadros, ‘The Homicide Ladder’ (2006) 69 MLR 601.

[14] Law Commission Report (2006), n 5 above at [1.63]. For further discussion see, Ashworth, above n 10, R. Taylor, ‘The Nature of “Partial Defences” and the Coherence of (Second Degree) Murder’ [2007] Crim L R 345.

[15] Law Commission Report (2006), n 5 above at [1.64]

[16] Law Commission Report (2006), n 5 above at [1.67]

[17] O. Quick and C. Wells, ‘Getting Tough with Defences’ [2006].

[18] R. D. Mackay, ‘The abnormality of mind factor in diminished responsibility’ [1999] Crim L R 117, 117

[19] For further discussion on the accession and practical application of diminished responsibility in England and Wales under the original definition, see E. E. Tennant, The Future of the Diminished Responsibility Defence to Murder (Chichester: Barry Rose, 2001).

[20] R. D. Mackay, ‘The Abnormality of Mind Factor in Diminished Responsibility’ [1999] Crim L R 117, 117. Elsewhere, Mackay discusses how court report writers have frequently failed to consider the bracketed causes, with the result that the majority of reports did not discuss the aetiological causes of the defendant’s abnormality of mind, see Law Commission Report (2004), n 5 above, Appendix B, Table 18, 156

[21] Law Commission Report (2006), n 5 above at [5.111]

[22] Criminal Justice and Licensing (Scotland) Act 2U10, s 16b, provides that the following definition be inserted into the Criminal Procedure (Scotland) Act 1995.

[23] A. Ashworth, Principles of Criminal Law (Oxford: OUP, 5th ed, 200).

[24] A. Ashworth, Principles of Criminal Law (Oxford: OUP, 5th ed, 200.

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