In relation to acts or omissions on or after 4 October 2010, critical changes to the law of homicide are made by the Coroners and Justice Act 2009. The issues are dealt with in part 2 chapter 1.

The first set of changes deals with diminished responsibility. Section 2 of the Homicide Act 1957 is amended in relation to this defence, reducing murder to manslaughter. The provision will now read:(1) A person (D) who kills or is a party to the killing of another is not to be convicted of murder if D was suffering from an abnormality of ­mental functioning which: (a) arose from a recognised medical condition;(b) substantially impaired D’s ability to do one or more of the things mentioned in subsection (1A); and (c) provides an explanation for D’s acts and omissions in doing or being a party to the killing.

The things mentioned in subsection 1A are the defendant’s ability: (a) to understand the nature of their own conduct;(b) to form a rational judgement; and(c) to exercise self-control.

This last category will be of particular importance in view of the changes in the law of provocation set out below. The defence will be available if the abnormality of mental functioning provides an explanation for the suspect’s conduct if it causes, or is a significant contributory factor in causing, the defendant to act as he did. It need not be the main or only reason.

The reference to an abnormality of mental functioning is a significant updating of the law, allowing both for a wider spectrum of mental illnesses than the existing law and for developments in medical science.

In relation to diminished responsibility, the burden of proof remains on the defence to establish the grounds to the civil standard.

Loss of controlThe most significant changes are, however, in the abolition of the defence of provocation. This is replaced by a new defence entitled, somewhat misleadingly, ‘loss of control’. Section 3 of the Homicide Act 1957 will cease to have effect and the new law is contained in sections 54–56 of the Coroners and Justice Act 2009.

Where a person kills or is party to a killing they are not to be convicted of murder but of manslaughter if:(a) their acts and omissions in doing or being a party to the killing resulted from ‘loss of self-control’;(b) the loss of self-control had a qualifying trigger (see section 55); and(c) a person of their sex and age, with a normal degree of tolerance and self-restraint and in their circumstances, might have reacted in the same or in a similar way.

It will no longer matter whether the loss of control was sudden. This will make it easier for the defence, particularly in respect of battered women, to run the slow-burn defence where a person has been subject to abuse over a long period of time when a final small act leads to the killing.

The mixed subjective and objective test of provocation continues into the new law. Thus a reference to the circumstances of the defendant is a reference to all of the defendant’s ­circumstances other than those whose only relevance to the defendant’s conduct is that they bear on the defendant’s general capacity for tolerance or self-restraint. A person with less than normal tolerance will need to identify a medical reason for it and plead diminished responsibility.

It should be particularly noted that if, in doing or being a party to the killing, the defendant acted in a considered desire for revenge, then this defence will not be available. This will apply to many male defendants, particularly when they discover infidelity on the part of their partners.

The burden of proof for this defence is the same as for provocation, namely the defence must raise the issue by evidence, but once they have done so the Crown must prove to the criminal standard that the defence is not made out. The statute indicates that it is a matter of law and for the judge to decide whether the defendant has sufficiently raised the issue.

The fact that one party to a killing is by virtue of these provisions not liable to be convicted of murder, does not affect the question of whether any other party may be convicted of the primary offence.

For there to be a ‘loss of control’ there must be a qualifying trigger. The meaning of these words is defined by section 55. It arises if the defendant’s loss of self control was attributed to:The detail in these provisions is extremely important. The current law is significantly tightened up. Furthermore, the section specifically provides that the fact that a thing done or said constitutes a sexual infidelity must be disregarded. This again will apply to many male defendants.

  • the defendant’s fear of serious ­violence from the victim against the defendant or another identified person; or
  • the defendant’s loss of self-control was attributed to a thing or things done or said or both which:
    • (a) constituted circumstances of an extremely grave character; and(b) caused the defendant to have a justifiable sense of being seriously wronged; or
  • a combination of those two triggers.

The result of these changes in the law is that great care will be needed in advice at the investigation stage. There are likely to be more ‘no comment’ interviews than had previously been the case, for fear that suspects will actually talk themselves out of the defence at a time when their circumstances are not fully understood.

There are further limitations provided by the section. The defendant’s fear of serious violence must be disregarded to the extent that it was caused by anything which the defendant incited to be said or done to provide an excuse for the use of violence; and a sense of being seriously wronged by a thing said or done is not justifiable if the defendant incited that thing for the purpose of providing an excuse to use violence.

InfanticideFinally, changes by section 57 of the Coroners and Justice Act 2009 to the law of infanticide. The law is clarified to make clear that a conviction for infanticide may only be allowed if the defendant would otherwise have been convicted of murder or of manslaughter.