lc290 Partial Defences to Murder report - Law Commission

In our law diminished responsibility applies in cases where, because
the accused’s ability to determine and control his actings is impaired
as a result of some mental abnormality, his responsibility for any
killing can properly be regarded as correspondingly reduced… . 67
In essence, the judge must decide whether there is evidence that, at
the relevant time, the accused was suffering from an abnormality of
mind which substantially impaired the ability of the accused, as
compared with a normal person, to determine or control his acts. …
The abnormality of mind may take various forms. It may mean that
the individual perceives physical acts and matters differently from a
normal person. Or else it may affect his ability to form a rational
judgement as to whether a particular act is right or wrong or to
decide whether to perform it. In a given case any or all of these
effects may be operating.
In essence the jury should be told that they must be satisfied that,
by reason of the abnormality of mind of the person in question, the
ability of the accused, as compared with a normal person, to
determine or control his actings was substantially impaired. 68
5.60 The Scottish Law Commission, in its Discussion Paper on the subject 69 put
forward a test which was similar to the versions (2) – (5) which we put forward for
discussion in our Consultation Paper. It suggested that the test should explicitly
state that its underlying rationale was that the plea acted as a mitigating
circumstance so as to reduce the charge of murder to one of culpable homicide.
The test envisaged the ultimate question to be posed to be whether:
his or her condition at the time of the commission of the offence
amounted to such extenuating circumstances as to justify a
conviction for culpable homicide instead of a conviction for murder. 70
5.61 This did not find favour with consultees to that Discussion Paper. They pointed
out that the definitions of other defences in criminal law do not set out their
rationales. The Scottish Law Commission accepted the point that had been made
by consultees. It said that as the rationale of diminished responsibility is well
understood, there is no need to include it as part of the test for the plea.
Furthermore, it thought that there might be a danger of confusing the different
roles of expert witnesses and jury were the test itself to refer to such matters as
conditions which justify a conviction on the lesser charge. 71
5.62 The Scottish Law Commission has not recommended this formulation but instead
has recommended a statutory formulation which mirrors the essence of Galbraith
namely:
67 2002 JC 1, para 41.
68 Ibid, at para 54.
69 Scottish Law Commission, Discussion Paper No 122 on Insanity and Diminished
Responsibility (2003).
70 Ibid, at para 3.38.
71 Scots Law Com No 195, para 3.16.
98