The new law of diminished responsibility refers to "abnormality of mental functioning" which has to arise from a "recognised medical condition". This change allows for a wider spectrum of mental illness and enables the law to keep pace with developments in medical science. The abnormality of mental functioning must have "substantially impaired" the defendant's ability to do "one or more" of three "things" which are:
- to understand the nature of his conduct;
- to form a rational judgment;
- to exercise self-control.
Finally, the abnormality of mental functioning must provide an explanation for the defendant's acts or omissions in doing or being a party to the killing. An abnormality of mental functioning will provide such an explanation if it causes, or is a significant contributory factor in causing, the defendant to carry out that conduct. It will be for the defendant to establish this defence to the civil standard: balance of probabilities.
Loss of control:
The next reform is arguably more problematic. The common law partial defence of provocation will be abolished and replaced by a new partial defence of "loss of control".
If the defendant's acts or omissions in doing or being a party to the killing resulted from the defendant's "loss of self control" then the defence may be available. The loss of self control has to arise from a "qualifying trigger" AND 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", might have reacted in the same or in a similar way to the defendant. It will not matter whether or not the loss of control was sudden. This latter point may be of help to those who final break after a lengthy period of abuse - often referred to as "slow burn" - see, as an example, the case of Kiranjit Ahluwalia.
The reference to "the circumstances of the defendant" is stated to be a reference to all of his circumstances other than those whose only relevance to his conduct is that they bear on his general capacity for tolerance or self-restraint. This is not entirely clear and it will be interesting to see how the courts apply it. (The explanatory notes may assist).
Where a defendant acted out of a "considered desire for revenge" then this defence will not be available.
The new law of "qualifying triggers" is complex. A qualifying trigger may be the defendant's fear of "serious violence" from the victim against the defendant or another "identified person". A further qualifying trigger is where the defendant's loss of self control was attributable to things done or said (or both) which constituted circumstances of an extremely grave character and caused the defendant to have a justifiable sense of being seriously wronged. There may be a combination of both triggers. There are a number of limitations . Fear of serious violence is to be disregarded to the extent that it was caused by a thing which the defendant incited to be done or said for the purpose of providing an excuse to use violence. Further, a sense of being seriously wronged by a thing done or said is not justifiable if the defendant incited the thing to be done or said for the purpose of providing an excuse to use violence. Finally, the fact that a thing done or said constituted sexual infidelity is to be disregarded.
Burden of proof for loss of self control:
The defence must raise "loss of control" by evidence. Whether they have achieved this is a question for the trial judge. If they have succeeded then 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.
These changes are far from easy to both interpret and apply. Appellate decisions will doubtless result.
In some quarters, the reform of provocation law has been seen as driven by a political feminist agenda -see "An unjust, feminist view of murder" - Sunday Times 30th July 2008.
Three tiers of homicide - a further possible change?
It seems likely that further changes to the law of homicide will arise if, as seems likely, the government adopts the "three tier structure" put forward by the Law Commission. The Guardian 8th September 2010 reported that the Director of Public Prosecutions is supporting such a change. Homicide would then comprise first and second degree murder and manslaughter. A degree of caution ought to be adopted here since the categories may prove, in practice, to be problematic and a degree of "under-charging" is a possibility - (as already occurs with the various degrees of assault).
It is disappointing that the new government has not opted for a thorough overhaul of the law of homicide. Piecemeal reform is adding complexity to an already over complex situation.
Addendum - 9th September: See "Murder by misnomers" - The Guardian - Afua Hirsch.
"Pressure grows for reform of murder law" - Ian Dunt in Politics.co.uk 8th September.
Addendum - 14th September: "Calls for murder law reform may be ignored" - UK Human Rights Blog
Addendum - 20th September: "Killing by Degrees" - interesting article on the need for fundamental reform, a need which has existed for many years. Despite the massive amount of criminal justice legislation since the 1960s, the law of murder remains as defined by common law.
Addendum - 25th October: "Homicide Reform under the CAJA 2009" - Rudi Fortson QC - Seminar held 16th October by the Criminal Bar Association of England and Wales. This is a very detailed look at the reforms but ought to be read by all practitioners.
Update Addendum 17th January 2012: The Court of Appeal Criminal Division - R v Clinton, Parker and Evans  EWCA Crim 2 - Lord Judge CJ, Henriques and Gloster JJ. The first appellate decision on the newly defined law of loss of control.