Diminished responsibility is a partial defence to murderthat when raised pleads guilty to voluntary manslaughter. Reason for raisingthis partial defence is that sentencing comes under judge’s discretion asopposed to mandatory life sentence for conviction to murder.The first stage is proving that the defendant suffered anabnormality of mental functioning which arouse from a recognised medicalcondition. This condition does not have to be a serious mental illness. Herringwrites in his criminal law textbook that the defendant must introduce evidencefrom an expert to establish the mental condition. The expert evidence must beaccepted if there is no contradictory evidence, but if there is othercontradictory evidence, the jury are entitled to reject the view of the expert.This was upheld in the case of R v Brennan 2014.
Secondly, the defendant must prove that the medicalcondition substantially impaired one or more of three things listed in the act.Namely the failure to understand the nature of the conduct which could meanthat the defendant does not know what he or she is doing or did not understandthe nature of his or her acts.An alternative ground for the defence is to argue that theabnormality substantially impaired the defendant’s ability to form a rationaljudgment.
There must be proof that the defendant’s ability to make anassessment of what is the right thing to do had been substantially impaired bythe mental abnormality. The final possible ground is that it affects the defendant’sability to exercise self-control. This ground is appropriate to rely on in acase where a defendant suffering from a mental abnormality and has lostself-control and killed.
The obvious exception is where there is evidence fromthe facts that the impairment of self control provides no explanation for theactual intent of the killing, such as when the killing was done in greed.The meaning of the word substantial has proved itssignificance because it suggests that there must not be a total impairment butmerely more than trivial. In the case of R v Mark Richard Gold (2016) itwas held that the jury should be given to understand that the expression was anordinary English word, that it imported a question of degree and that whetherin the case before it the impairment could properly be described as substantialwas for it to resolve. A review of authorities shows that in the context of diminishedresponsibility the word ‘substantially’ has always been held to be used in thesense of being ‘important and weighty’. The final step to succeeding with this defence lies with Section2(1)(c) which requires the defendant to show causation.
The jury needs todetermine that the mental condition was such as to cause the substantialimpairment that resulted in the defendant’s acts or omissions leading to thekilling. The Law Commission upheld this and stated that there has to be anappropriate connection between the mental functioning and the killing. The Ministry of Justice also supported this by stating thatthe mental conditions impairment need not be the sole cause of the defendant’sbehaviour, but it should be a significant contributory factor in causing theconduct.Voluntary acute intoxication will not suffice tosuccessfully raise the partial defence of diminished responsibility asestablished in R v Dowds (2012). The amendment of this partial defencewas not intended to reverse the well established rule that voluntary acuteintoxication is not capable of being relied upon to successfully raise thepartial defence of diminished responsibility. Judge Wait in the case relied inrefusing to leave diminished responsibility to the jury on the factor that thecondition of the defendant was a temporary one.
The principle of this partial defence is that in practice, it causes the defendant to plead guilty tomanslaughter. Herring writes in his criminal law textbook that the prosecutionwill often accept a diminished responsibility plea but only when there is clearevidence of the defendant’s mental abnormality. If evidence is not sufficientthen the jury will be left to decide.Fitzgerald QC in a writes in his article titled ‘The Defenceof Diminished Responsibility’ that diminished responsibility was introducedbecause of the limitations of the insanity defence and the need to recognisethat less severe forms of mental malfunctioning could also reduceresponsibility so as to make it unjust to sentence the person to death. He alsotheorised that the partial defence still exists today to protect those that donot deserve to be sentenced to a mandatory life sentence.
The burden of proof for diminished responsibility lies withthe defence to prove all parts necessary on a balance of probabilities. This isreiterated in the law, especially on authority from previously mentioned caseof R v Brennan 2014 where the defendant introduced evidence from a consultantpsychiatrist, which supported the defence. The crown did not raise anycontradictory expert evidence and the jury convicted the defendant for murder.On appeal, the murder conviction was quashed and it was held that the jury hadno rational basis to depart from uncontradicted and unchallenged expertevidence.The fact that the burden of proof lies with the defendanthas been criticised that it breaches Article 6(2) of the European Convention ofHuman Rights that everyone charged with a criminal offence shall be presumedinnocent until proven guilty.
Herring explains that it is consistent withinternational treaty because the prosecution has to prove the elements ofmurder and also, the defence has a choice whether or not to raise diminishedresponsibility.