Diminished responsibility is a partial defence to murder
that when raised pleads guilty to voluntary manslaughter. Reason for raising
this partial defence is that sentencing comes under judge’s discretion as
opposed to mandatory life sentence for conviction to murder.
The first stage is proving that the defendant suffered an
abnormality of mental functioning which arouse from a recognised medical
condition. This condition does not have to be a serious mental illness. Herring
writes in his criminal law textbook that the defendant must introduce evidence
from an expert to establish the mental condition. The expert evidence must be
accepted if there is no contradictory evidence, but if there is other
contradictory 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 medical
condition substantially impaired one or more of three things listed in the act.
Namely the failure to understand the nature of the conduct which could mean
that the defendant does not know what he or she is doing or did not understand
the nature of his or her acts.
An alternative ground for the defence is to argue that the
abnormality substantially impaired the defendant’s ability to form a rational
judgment. There must be proof that the defendant’s ability to make an
assessment of what is the right thing to do had been substantially impaired by
the mental abnormality.
The final possible ground is that it affects the defendant’s
ability to exercise self-control. This ground is appropriate to rely on in a
case where a defendant suffering from a mental abnormality and has lost
self-control and killed. The obvious exception is where there is evidence from
the facts that the impairment of self control provides no explanation for the
actual intent of the killing, such as when the killing was done in greed.
The meaning of the word substantial has proved its
significance because it suggests that there must not be a total impairment but
merely more than trivial. In the case of R v Mark Richard Gold (2016) it
was held that the jury should be given to understand that the expression was an
ordinary English word, that it imported a question of degree and that whether
in the case before it the impairment could properly be described as substantial
was for it to resolve. A review of authorities shows that in the context of diminished
responsibility the word ‘substantially’ has always been held to be used in the
sense of being ‘important and weighty’.
The final step to succeeding with this defence lies with Section
2(1)(c) which requires the defendant to show causation. The jury needs to
determine that the mental condition was such as to cause the substantial
impairment that resulted in the defendant’s acts or omissions leading to the
killing. The Law Commission upheld this and stated that there has to be an
appropriate connection between the mental functioning and the killing.
The Ministry of Justice also supported this by stating that
the mental conditions impairment need not be the sole cause of the defendant’s
behaviour, but it should be a significant contributory factor in causing the
Voluntary acute intoxication will not suffice to
successfully raise the partial defence of diminished responsibility as
established in R v Dowds (2012). The amendment of this partial defence
was not intended to reverse the well established rule that voluntary acute
intoxication is not capable of being relied upon to successfully raise the
partial defence of diminished responsibility. Judge Wait in the case relied in
refusing to leave diminished responsibility to the jury on the factor that the
condition of the defendant was a temporary one.
The principle of this partial defence is that in practice, it causes the defendant to plead guilty to
manslaughter. Herring writes in his criminal law textbook that the prosecution
will often accept a diminished responsibility plea but only when there is clear
evidence of the defendant’s mental abnormality. If evidence is not sufficient
then the jury will be left to decide.
Fitzgerald QC in a writes in his article titled ‘The Defence
of Diminished Responsibility’ that diminished responsibility was introduced
because of the limitations of the insanity defence and the need to recognise
that less severe forms of mental malfunctioning could also reduce
responsibility so as to make it unjust to sentence the person to death. He also
theorised that the partial defence still exists today to protect those that do
not deserve to be sentenced to a mandatory life sentence.
The burden of proof for diminished responsibility lies with
the defence to prove all parts necessary on a balance of probabilities. This is
reiterated in the law, especially on authority from previously mentioned case
of R v Brennan 2014 where the defendant introduced evidence from a consultant
psychiatrist, which supported the defence. The crown did not raise any
contradictory expert evidence and the jury convicted the defendant for murder.
On appeal, the murder conviction was quashed and it was held that the jury had
no rational basis to depart from uncontradicted and unchallenged expert
The fact that the burden of proof lies with the defendant
has been criticised that it breaches Article 6(2) of the European Convention of
Human Rights that everyone charged with a criminal offence shall be presumed
innocent until proven guilty. Herring explains that it is consistent with
international treaty because the prosecution has to prove the elements of
murder and also, the defence has a choice whether or not to raise diminished