Incapacitating Conditions in United Kingdom

Capacity and Incapacitating Conditions in Criminal Law

The new diminished responsibility defence

Substantially impaired ability

Michael J. Allen (Textbook on Criminal Law, Twelfth Edition, 2014) says:

“In Golds [2014] EWCA Crim 748, however, the Court of Appeal had to consider whether
the meaning of “substantial” should be limited to “more than trivial”.

D had been charged with murder and the three psychiatrists (two for the defence and one
for the Crown) were agreed that he was suffering from a significant level of mental illness
and that the criteria in s. 2 were satisfied. The plea of guilty to manslaughter was not
accepted and the issue went to the jury who convicted D of murder. Counsel for D had
contended that the trial judge should direct the jury that his impairment must be treated as
“substantial” if the effect of the abnormality of mental functioning on his ability to do the
things specified in s.2(1A) was “more than trivial”.

The trial judge refused leaving the jury to determine for themselves the meaning of “substantial”. D appealed. The essence of the appeal was that “substantial” was capable of having two different meanings either the meaning counsel had argued for at trial or a more stringent meaning to the effect that the abnormality of mental functioning only substantially impairs where, whilst not totally impairing a defendant’s ability to do the specified things, it significantly or appreciably impairs that ability. The Court of Appeal dismissed the appeal accepting jurisprudence from the old defence of diminished responsibility to the effect that judges, if requested by the jury for further explanation of the meaning of “substantial” should either refuse to give it as “substantial” is an ordinary word for the jury to apply using their common sense, or if further direction was considered necessary a direction adapting one given in Simcox

[1964] Crim LR 402 should be used. As adapted this might say:

Do we think, looking at it broadly as common-sense people, there was a substantial
impairment of his [ability to do one or more of the things listed in s. 2(1A)]? If the answer is
‘no’, there may be some impairment, but we do not think it was substantial, we do not
think it was something that really made any great difference, although it may have made it
harder [for him to do one or more of those things], then you would find him guilty…

The impact of this decision will only become clear with the passage of time. It might lead
to fewer pleas of guilty on the basis of diminished responsibility being accepted with more
cases going to trial leaving it to juries to wrestle with the substantial impairment problem.”