Diminished Responsibility

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Definition of Diminished Responsibility

Diminished responsibility is a defence only to murder and, if successful, reduces the charge to manslaughter. It is defined in s2(1) of Homicide Act 1957, and amended by the Coroners and Justice Act 2009.

The defendant must show that he/she suffered from an abnormality of mental functioning, arising from a recognised medical condition, which provides an explanation for committing the killing. It must be shown that the abnormality substantially impaired his/her ability to understand the nature of his/her conduct, form a rational judgment, and exercise self-control.

The burden of proof is on the defendant when raising diminished responsibility (i.e. the defendant has to prove diminished responsibility), but only on a balance of probabilities (i.e. the defendant needs to prove diminished responsibility is more likely than not).

Often the court will not challenge a defendant raising diminished responsibility, but the Court of Appeal in R v Vinagre (1979) said the prosecution should only leave the defendant without challenge if there is sufficient evidence of his mental abnormality.

"Abnormality of mental functioning"

The old law required an abnormality of the mind: thus, in R v Byrne [1960] it was stated that if the defendant’s mind is different from that of a normal mind then that would suffice.

The new law requires a "recognised mental condition". Thus, the defendant's successful reliance on 'Othello Syndrome' to plead diminished responsibility in R v Vinagre (1979) would not work under the new law unless 'Othello Syndrome' was a "recognised medical condition".

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CONTENT

The effect of the abnormality of mental functioning

The abnormality of mental functioning must "substantially impair" the defendant's ability to be rational and exercise self-control.

The leading case on the meaning of substantial is R v R [2010].

Diminished responsibility and intoxication

The issue of how the jury should deal with a case where the defendant was both intoxicated and had an abnormality of mental functioning during the killing has been addressed in R v Stewart [2009]. Note: this case was decided under the old law, but it is likely a similar approach will be followed under the current law.

Also see the cases of R v Dietschmann [2003] and R v Dowds [2012].