Explanation of the new law
The Coroners and Justice Act 2009 transforms the partial defences available to the charge of murder. The defence of provocation arising from the Homicide Act 1957 has been replaced with the defence of loss of control. Although loss of control is evocative of provocation, it is more prescriptive. The cause of the derangement must now have a 'qualifying trigger' under Section 55CJA 2009. Controversially Parliament specified that sexual infidelity was to be disregarded as a qualifying trigger Whilst sexual infidelity cannot provide an excuse to deliver fatal blows as a punishment, it is capable of arousing strong emotions. It must surely be illogical for a fact finder to be free to consider any other betrayal within a relationship but a sexual one. Sexual infidelity is not excluded from consideration. It can no longer be the sole basis of the defence of loss of control but it can be considered as part of a course of conduct.
Murder must not be trivialised. It is the gravest of offences and deserving of severe punishment. However, the law has long recognised that some offences are committed in circumstances which do not warrant a conviction for the full offence. The old defence of provocation lacked consistency and was said to operate unfairly against the vulnerable. To remedy this Parliament replaced it with Sections 54 and 55 CJA 2009. This departure does bring some improvements. No longer is the discomposure required to be an immediate response to one single act of provocation. The defence of loss of control recognises the cumulative effects of a large number of events that would not individually amount to provocation.
There remains capacity for injustice. Loss of control can be raised by relying upon any other form of disloyalty by a lover but a sexual one. In Lewis (Tabeel) v State of Trinidad and Tobago  UKPC 15 a Jehovah's Witness killed his partner to prevent her from disclosing their affair to the religious community and was able to rely on this defence. The sexual behaviour of the victim can even constitute loss of control in a case where there was no relationship with the killer. In Stingel v R (1990) 171 C.L.R. 312 a stalker stabbed his victim when he found her having sexual intercourse with another. He faced no obstacle in raising loss of control because she was not his partner. A jealous spouse with more understandable feelings of betrayal would be excluded from raising a defence on those facts.
Section 56 CJA 2009 sweeps away the defence of provocation. Section 54 CJA offers a partial defence to murder where a person has caused the death of another by reason of his 'loss of control'. The loss of control must be caused by a 'qualifying trigger' under Section 54[b]. A qualifying trigger can include a defendant's fear of serious violence from the deceased person or another identifiable person under Section 55 in circumstances where the full defence of self defence is not available. Under Section 55 a qualifying trigger can also include a thing said or done or both if it constituted circumstances of an 'extremely grave character' and this caused the defendant to have a 'justifiable sense of being seriously wronged'. When considering a thing said or done, under Section 55[c], sexual infidelity is to be disregarded. Previously a single instance of sexual infidelity was sufficient to raise the defence of provocation but it was ultimately often unsuccessful. Such defences fell when the jury were required to consider whether or not the provocation complained of was sufficient to make a reasonable man behave as the defendant did. While a reasonable jury properly directed would readily accept that a lover is properly entitled to be angered at his partner's infidelity, it may very well not accept that delivering a fatal blow was a reasonable reaction. Now a single instance of sexual infidelity can still be relied upon by a defendant seeking to show loss of control. Section 55[c] CJA 2009 does not exclude evidence of sexual infidelity but it prescribes that it cannot alone be sufficient for loss of control to succeed.
An acknowledgement of the impact of sexual infidelity is evident in Section 54. Sections 54[c] and  demand that the Court must consider all of the defendant's circumstances and does not exclude any sexual betrayal he has suffered. Section 54[c] requires a fact finder to consider whether a 'person of D's sex and age, with a normal degree of tolerance and self restraint and in the circumstances of D, might have reacted in the same or similar way'. Section 54 makes clear that 'the circumstances of D is a reference to all of D's circumstances other than those whose only relevance to D's conduct is that they bear on D's general capacity for tolerance and self restraint'.
The admissibility of sexual infidelity was recently considered in the case of Clinton  EWCA Crim 2. This case involved sexual infidelity during the course of a relationship breakdown. The defendant had been prevented from raising loss of control. The Court of Appeal concluded that in cases where sexual betrayal amounted to the only trigger for loss of control, then the prohibition in Section 55[c] must be applied. Nevertheless, evidence of sexual infidelity was admissible to form part of a course of conduct sufficient to cause loss of control. Now that the loss of control need not be immediate, a course of conduct can be relied upon to raise the new defence.
Provocation created disproportionate reliance upon sexual infidelity. The CJA 2009 seeks to stamp out outdated views of possession of a partner. However, a prohibition upon relying upon sexual infidelity to justify a fatal act of violence does not equate to an exclusion of evidence of sexual infidelity. Sexual infidelity may well be considered insufficient to drive the reasonable person to the most serious offence of violence in English law but a course of conduct which includes such disloyalty may be enough.