Voluntary manslaughter occurs where D possesses the AR and MR for murder but there are mitigating circumstances that allow for the use of a special partial defence that reduces the conviction to voluntary manslaughter.
These defences are only available to murder (special) and are partial defences as they reduce criminal liability, rather than producing an acquittal. If successfully pleaded, D will be convicted of voluntary manslaughter instead of murder and thus avoids the label of ‘murderer’ and a mandatory term in prison under the Murder (Abolition of Death Penalty) Act 1965. Instead the sentence is discretionary with life imprisonment as the maximum thus allowing a judge to reflect Ds actual culpability.
D cannot be charged with voluntary manslaughter; it is the result of successfully raising a defence. The offence is murder, a defence is then raised, and the resulting conviction is then voluntary manslaughter.
The special partial defences to murder, defined originally in the Homicide Act 1957, have long been the subject of criticisms and reforms. They have finally been amended by the CORONERS AND JUSTICE ACT 2009 (which received royal assent 12th November 2009, and came into force 4th October 2010). These changes are in line with the Law Commission’s proposals in their Report, Murder, Manslaughter and Infanticide (2006).
DR~The OLD law
Diminished responsibility did not exist in the common law. It was introduced as a statutory defence to murder in the HOMICIDE ACT 1957 and defined in Section 2 Homicide Act 1957.
The burden of proof is on D (on the balance of probabilities) which is known as the reverse onus as it requires D to prove he was suffering from diminished responsibility.
D must prove:
- He was suffering from an ABNORMALITY OF THE MIND
- Which was caused by ARRESTED OR RETARDED DEVELOPMENT OF THE MIND OR AN INHERENT CAUSE OR DISEASE OR INJURY and
- The abnormality of the mind SUBSTANTIALLY IMPAIRED HIS MENTAL RESPONSIBILITY FOR THE KILLING.
Abnormality of the mind
R v Byrne 
Lord Parker CJ described this as: “...a state of mind so different from that of ordinary human beings that the reasonable man would consider abnormal.”
This was a very wide definition and could therefore cover a wide range of conditions:
There was no requirement for any permanence in the condition, or for it to have been present since birth.
The question of whether D was suffering from an abnormality of the mind was for the jury to decide, having heard expert medical evidence (which they are not bound to accept). Medical evidence is therefore crucial in diminished responsibility cases. Where D was suffering a condition that was not at the time of the trial, regarded by psychiatrists as a mental condition the defence will be unavailable but, if the condition subsequently becomes so recognised, a conviction may then be quashed on appeal/retrial ordered.
R v Hobson 1998
D was tried October 1992 for the murder of her abusive, alcoholic partner who she stabbed to death. The trial judge left self-defence and/or provocation to the jury but diminished responsibility was not raised and D was convicted.
In May 1997 D appealed on the grounds that evidence at her trial now supported a plea of diminished responsibility based on the ‘new’ condition battered woman’s syndrome. In 1994 the condition was included in the standard British classification of mental diseases, but was not a condition that would have been readily considered by practising psychiatrists in 1992. CA allowed the appeal and ordered a re-trial.
R V Dix 1982
CA declared that medical evidence was a “practical necessity if the defence is to begin to run at all”. The jury were not, however, bound to accept that evidence if there was other material, which, in their opinion, conflicted with and outweighed the medical evidence. They are then required to weigh up and choose between different opinions.
Causes of abnormality
The abnormality had to be caused by one of the triggers/matters set out within s.2 HA 1957 and it must be SUPPORTED BY MEDICAL EVIDENCE. D cannot simply assert a condition without proof.
CONDITION OF ARRESTED OR RETARDED DEVELOPMENT:
o Any mental deficiency/lack of mental awareness.
ANY INHERENT CAUSE:
o One from within D, not an outside factor.
o Need not be permanent.
o Need not be inherited, or present since birth.
INDUCED BY DISEASE OR INJURY:
o Disease: such as a traumatic event leading to PTSD.
o Injury: such as a blow to the head causing brain damage.
“Substantial does not mean total, that is to say, the mental responsibility need not be totally impaired, so to speak, destroyed all together. At the other end of the scale, substantial does not mean trivial or minimal...
This direction was not definite and fixed and thus it allowed for jury discretion. However, as it is a question of fact, the judge can withdraw the point from the jury if there is insufficient evidence on which a reasonable jury could conclude that Ds responsibility was substantially impaired. Therefore, a judge had to be convinced that the evidential basis has been satisfied. If not initially convinced in the applicability of the defence, a judge could remove it from the jury’s consideration.
To a certain extent, once the issue is left to the jury, sympathy for D can make all the difference between the un/successful plea. On the one hand, it is not uncommon for manslaughter verdicts to be returned in cases with minimal evidence of abnormality, but where D has reacted to situations of extreme grief/stress: thus mercy killings receive manslaughter convictions Heginbotham 2004. Conversely, murder convictions have been returned in cases when the psychiatrists all agree that D was suffering an abnormality but whose actions evoked little or no sympathy. See Sutcliffe . Therefore, this part of the decision making is based as much on moral factors as it is on medical ones.
The problems with old DR
BURDEN OF PROOF~Many commentators feel the burden resting on the D represents an unfair hurdle not faced by Ds claiming most other defences. However, in R v Lambert  the HL decided there is no breach of Article 6 ECHR. MEDICAL EVIDENCE~Quite often the whole case turns on conflicting P and D medical evidence. This means a lay jury has to decide whose medically trained opinion to believe/accept! WORDING OF S.2 HA 1957~The Law Commission, in its report “Murder, Manslaughter and Infanticide” 2006, pointed out two principal problems with the current provisions: (i) s.2 does not explain a ‘substantial impairment of mental responsibility’. (ii) s.2 was not drafted with the needs and practices of medical experts in mind. In particular, abnormality of the mind is not a psychiatric term. DEFENCE USED FOR POLICY REASONS~ a safeguard of this is that the judge does not have to agree with the prosecution and can insist a trial go ahead. Sutcliffe~The judge refused the plea and Sutcliffe was tried for murder. This raises another problem as juries, in unpleasant murder trials, may then make decisions based on their feelings towards the D and convict of murder, even if D has an abnormality. NEGATIVE STEREOTYPE OF WOMEN~ by focusing more on the state of mind of an abused woman rather than correctly emphasising the abuse she has suffered at the hands of the deceased. Any label of D.R can have future implications.
Introduction to new DR law
Diminished responsibility did not exist in English common law. It is a statutory defence first introduced by s.2 Homicide Act 1957. This section was however recently amended by s.52 CORONERS AND JUSTICE ACT 2009 (which came into force 4th October 2010) in line with the Law Commission’s proposals in their Report, Murder, Manslaughter and Infanticide (2006). s.52 CORONERS AND JUSTICE ACT 2009 amends diminished responsibility by adding a new section 2 into the Homicide Act 1957. The defence is now broken down into 4 parts.
s.2 Homicide Act 1957:
A person (“D”) who kills or is 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 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.
- ‘Abnormality of mental functioning’ replaces the original phrase ‘abnormality of mind’.
- ‘Recognised medical condition’ replaces the original list of causes: ‘condition of arrested or retarded development of mind’, ‘any inherent causes’ or ‘induced by disease or injury’.
- ‘Substantially impaired’ ability to ‘understand the nature of Ds conduct’, ‘form a rational judgment’ or ‘exercise self control’ replaces the original phrase ‘substantially impaired mental responsibility’.
- The requirement that Ds abnormality of mental functioning ‘provides an explanation’ for Ds involvements in killing V is a new element.
Notwithstanding the amendments, much of the pre 2009 case law from the original s.2 HA 1957 continue to be relevant.
Abnormality of mental functioning
This is a new phrase, replacing ‘abnormality of mind’. The Law Commission explained the reason for the change by stating that the original definition in s. 2(1) HA 1957 had not been “drafted with the needs and practices of medical experts in mind, even though their evidence is crucial to the legal viability” of any DR defence.
‘Abnormality of mind’ was also not a psychiatric term and it received no further definition in the HA 1957. In practice, the courts interpreted the phrase very widely.
R v Byrne  Byrne was a sexual psychopath who strangled a young woman and then mutilated her body. Medical evidence showed him to have a condition making him unable to control himself. He was convicted of murder but the CA quashed the conviction and substituted voluntary manslaughter as it held the condition came within the definition of DR. Byrne was nevertheless imprisoned for life.
Within the new Coroners and Justice Act 2009, there is no further statutory definition of “abnormality of mental functioning”. There is also nothing in s.52 CAJA 2009 to indicate that the ‘abnormality of mental functioning’ has to have any degree of permanence, or to have existed since birth. It just needs to be operating at the time of the killing (so this is the same as under the old provisions.)
Recognised medical condition
Formerly, the original s.2 (1) HA 1957 required the ‘abnormality of mind’ to arise from a condition of arrested or retarded development of mind, any inherent cause orinduced by disease or injury.
This list has now been consolidated into the single and simpler requirement of a ‘RECOGNISED MEDICAL CONDITION’. Re-definition brang existing terminology up to date while allowing future developments in diagnostic practice.
Again, there is no further definition of ‘recognised medical condition’ provided in the 2009 Act. However, it is reasonable to assume that courts will continue to accept the following conditions which all fell within the scope of the original s.2 (1) HA 1957.eg
- Adjustment disorder (R v Dietschmann )
- Battered Woman Syndrome (R v Hobson )
It is possible that there will be more than one cause of Ds abnormality of mental functioning. If both causes are medical conditions, then if anything Ds defence is strengthened.
The need for a DR plea to be founded on a “recognised medical condition” may, however, make it more difficult for psychiatrists to bring “mercy killing” cases.
SUBSTANTIALLY IMPAIRED ABILITY TO UNDERSTAND THE N
Another new addition, replacing the original expression “substantially impaired mental responsibility” used in s. 2 (1) HA 1957, following criticism that the old phrase was too vague. The CAJA 2009 makes it clear. D must now prove that his abnormality of mental functioning impaired his “ability to understand the nature of his/her conduct” and/or “form a rational judgment” and/or “exercise self control”.
SUBSTANTIAL IMPAIRMENT?~~~In short, there is no “scientific test” for measuring this aspect of the defence. It therefore remains a question for the jury and explains the role they play in this defence. The phrase ‘substantial impairment’ has been lifted from the original s.2 HA 1957 and thus it is likely that the explanation from Lloyd  will endure, leaving it up to the jury. For the new DR plea to succeed, the abnormality must have substantially affected Ds ability to:
- “understand the nature of his/her conduct” and/or
- “form a rational judgment” and/or
- “exercise self control”.
This new approach of spelling out what abilities need to be impaired inevitably means that “abnormality of mental functioning” is now narrower than “abnormality of mind” because the only activities of the mind which are included are those specified.
ABNORMALITY MUST PROVIDE ‘AN EXPLANATION’ FOR Ds A
This is another entirely new principle which clarifies the previous position by requiring there to be some causal connection between Ds mental abnormality and the killing. The abnormality of mental functioning will provide an explanation it is causes, or is a significant contributory factor in causing, D to carry out the conduct of killing.
The use of the word ‘an’ explanation, as opposed to ‘the’ explanation meaning that although the ‘abnormality’ must at least be a ‘significant contributory factor’ for D killing, it need not necessarily be the sole explanation.
The Government agreed with Law Commission that it would be impractical to require the abnormality to be the only reason for Ds behaviour on the basis that “it is rare that a person’s actions will be driven solely from within to such an extent that they would not otherwise have committed the offence, regardless of the influence of external circumstances, and a strict causation requirement of this kind would limit the availability of the partial defence too much.”
However, the MoJ also made it clear that the defence “should certainly not succeed where the jury believes that the impairment made no difference to the D’s behaviour – he would have killed anyway”.
Key Improvements from s.52 Coroners and Justice Ac
1. The concept of “abnormality of mind” has been replaced by “abnormality of mental functioning” which the Law Commission finds preferable because it expressly requires experts to consider the way in which the offender’s mental processes were affected by reason of a mental condition.
2. The abnormality must be recognised by the medical profession, rather than being a transitory state of heightened emotions. The wording “recognised medical condition” allows for the law to develop with changing medical knowledge of mental health conditions.
3. It sets out clearly the aspects of the D’s functioning which must be substantially impaired in order for the partial defence of DR to succeed.