Introduction
In the criminal law of England and Wales, murder carries a mandatory life sentence. However, the law recognises that not all killings are equally blameworthy. Where a defendant has committed the actus reus and has the mens rea for murder, they may be able to rely on a partial defence which, if successful, reduces the conviction from murder to voluntary manslaughter. This allows for judicial discretion in sentencing. The two principal partial defences are loss of control and diminished responsibility, both of which were significantly reformed by the Coroners and Justice Act 2009 (CJA 2009). This essay will critically analyse the current law on these two defences. It will argue that while the CJA 2009 succeeded in modernising the law and addressing some clear failings of the previous defences of provocation and diminished responsibility, the new legal frameworks have introduced their own set of problems, particularly regarding the restrictive nature of the qualifying triggers for loss of control and the medicalisation of diminished responsibility.
The Reforming Ambition of the Coroners and Justice Act 2009
The CJA 2009 was enacted to reform areas of the law on homicide that had been subject to long-standing criticism. The old law of provocation, under section 3 of the Homicide Act 1957, was seen as problematic. It required a "sudden and temporary" loss of control, which was argued to be discriminatory against victims of long-term abuse, who may kill after a "slow-burn" of provocation rather than a sudden outburst (Ormerod and Laird, 2021). Cases such as R v Ahluwalia [1992] 4 All ER 889 highlighted this issue. Furthermore, the defence was criticised for being too generous to men who killed out of anger or sexual jealousy. The old law on diminished responsibility, also in the 1957 Act, was considered outdated, using vague terminology such as "abnormality of mind" which lacked clear medical grounding. The CJA 2009 therefore sought to create more tightly defined and modern defences that better reflected contemporary social and medical understanding.
Loss of Control
The defence of provocation was abolished and replaced by the new partial defence of loss of control, contained in sections 54 and 55 of the CJA 2009. Section 54(1) sets out a three-part test, all elements of which must be present. The killing must have resulted from the defendant's loss of self-control, this loss of self-control must have had a qualifying trigger, and a person of the defendant's sex and age, with a normal degree of tolerance and self-restraint, might have reacted in the same or a similar way.
A key change is the removal of the requirement for the loss of control to be "sudden" (s.54(2)). This was a direct response to the perceived gender bias of the old law and, in principle, allows the defence to be available to those who kill after a period of abuse. However, the longer the delay between the provocative act and the killing, the less likely it is that the jury will find there was a genuine loss of self-control (s.54(2)).
The most significant and controversial part of the new defence lies in the restrictive "qualifying triggers" set out in section 55. There are two such triggers. The first is where the defendant's loss of control was attributable to a fear of serious violence from the victim (s.55(3)). The second is where it was attributable to things said or done which constituted circumstances of an extremely grave character and caused the defendant to have a justifiable sense of being seriously wronged (s.55(4)). The introduction of these high thresholds was intended to prevent the defence from being used in trivial circumstances. However, the wording of the second trigger is vague and creates uncertainty. What constitutes "extremely grave" circumstances and a "justifiable sense of being seriously wronged" is left to the jury to decide on a case-by-case basis, potentially leading to inconsistent outcomes.
Furthermore, section 55(6)(c) explicitly states that "the fact that a thing said or done constituted sexual infidelity is to be disregarded". Parliament’s intention was to prevent defendants from using sexual jealousy as an excuse for murder. While this may seem a laudable aim, the Court of Appeal in R v Clinton, Parker & Evans [2012] EWCA Crim 2 found the provision difficult to apply in practice. The court held that while sexual infidelity cannot be a qualifying trigger on its own, it can be considered as part of the general context and circumstances when evaluating the other triggers and the objective test. This judicial interpretation appears to undermine the clear legislative wording, creating confusion about the exact role sexual infidelity can play in the defence. This judicial attempt to make the law workable illustrates a key flaw in the drafting of the Act.
The final element is an objective test: would a person of the defendant's sex and age, with a normal degree of tolerance and self-restraint and in the circumstances of the defendant, have reacted similarly? This is largely a re-statement of the old law. The case of R v Asmelash [2013] EWCA Crim 157 confirmed that voluntary intoxication is not a relevant "circumstance" for the jury to consider, meaning the defendant is to be judged against a sober person. While this provides a clear policy-driven rule, it can be argued that it fails to reflect the reality of many violent situations.
Diminished Responsibility
The CJA 2009 also reformed the defence of diminished responsibility by amending section 2 of the Homicide Act 1957. The new section 2(1) requires a defendant to show that they were suffering from an "abnormality of mental functioning" which (a) arose from a recognised medical condition, (b) substantially impaired their ability to do one or more of the things mentioned in subsection (1A), and (c) provides an explanation for their acts and omissions in doing or being a party to the killing.
This new definition is more structured and medically grounded than the old law. The replacement of "abnormality of mind" with "abnormality of mental functioning" reflects a shift to modern psychiatric language. The requirement for the abnormality to arise from a "recognised medical condition" (s.2(1)(a)) provides a clearer, more objective basis for the defence, relying on established diagnostic manuals like the DSM-5 or ICD-10. This has made the defence more reliant on expert medical evidence.
The Act also specifies the ways in which the defendant's ability must be "substantially impaired" (s.2(1A)): to understand the nature of their conduct, to form a rational judgment, or to exercise self-control. This provides helpful clarity compared to the old, more general test. However, the meaning of "substantially" has remained a source of contention. In R v Golds [2016] UKSC 61, the Supreme Court clarified that the impairment must be "weighty" and "important", and more than merely trivial. The Court advised judges against attempting to explain the term further to the jury, suggesting that its ordinary meaning is sufficient. Despite this guidance, it remains a question of degree for the jury, introducing an element of subjectivity into a supposedly more objective test.
The issue of intoxication continues to pose problems. In R v Dowds [2012] EWCA Crim 281, the court held that acute voluntary intoxication cannot, in itself, be a recognised medical condition capable of founding a DR defence. However, the situation is more complex where a defendant with a pre-existing condition is also intoxicated. In R v Stewart [2009] EWCA Crim 593, a case concerning Alcohol Dependency Syndrome, the court outlined factors for the jury to consider, such as the seriousness of the dependency. This demonstrates that the interaction between mental conditions and intoxication remains a complex factual issue for juries, and the CJA 2009 has not provided a simple solution.
Conclusion
The reforms to the partial defences to murder introduced by the Coroners and Justice Act 2009 were a necessary and overdue response to the widely acknowledged failings of the old law. In many respects, the Act has been a qualified success. The defence of diminished responsibility is now on a firmer, more modern medical and legal footing, even if ambiguity remains around key terms like "substantial". The loss of control defence rightly removed the "sudden" requirement, providing a potential route for victims of domestic abuse who kill their abusers.
However, the analysis has shown that the new law is far from perfect. The attempt to create a tightly-defined loss of control defence through the qualifying triggers has proven problematic. The rules are complex and the categorical exclusion of sexual infidelity has been undermined by judicial interpretation in Clinton, suggesting that the legislative drafting was flawed. The high thresholds for the "anger" trigger may have made the law too restrictive, potentially excluding deserving cases. Ultimately, while the CJA 2009 has clarified certain aspects of voluntary manslaughter, it has simultaneously created new areas of complexity and controversy. The law is now more structured, but whether it is fairer or more just in all circumstances remains a matter for debate.
References
Cases
R v Ahluwalia [1992] 4 All ER 889
R v Asmelash [2013] EWCA Crim 157
R v Clinton, Parker & Evans [2012] EWCA Crim 2
R v Dowds [2012] EWCA Crim 281
R v Golds [2016] UKSC 61
R v Stewart [2009] EWCA Crim 593
Legislation
Coroners and Justice Act 2009
Homicide Act 1957
Secondary Sources
Ormerod, D. and Laird, K. (2021) Smith, Hogan, and Ormerod's Criminal Law. 16th edn. Oxford: Oxford University Press.
