Diminished responsibility
D, a sexual psychopath pleaded diminished responsibility, having killed a woman while suffering from violent sexual desires, which he could not resist or had difficulty resisting. The trial judge ruled that such impulses or urges did not fall within the defence. The D was convicted of murder and appealed. The C of A allowed the Dís appeal and manslaughter was substituted. The court held that there had been a misdirection by the trial judge. Abnormality of mind was a state of mind so different from that if an ordinary human being that the reasonable person would turn it abnormal.
The case suggested that substantial impairment might equate with partial or borderline insanity. This was severely critised later in Seers.
The D killed his estranged wife whilst suffering from chronic depression. He was convicted of murder following a direction by the trial judge that the test for diminished responsibility was whether the D was partially or border line insane.
The C of A allowed his appeal and substituted manslaughter on the basis of a misleading direction. The court held that there was sufficient evidence that responsibility had been seriously, meaning more that trivially, therefore substantially impaired.