Before section 52 of the 1995 Act insert—
(1)A person is not criminally responsible for conduct constituting an offence, and is to be acquitted of the offence, if the person was at the time of the conduct unable by reason of mental disorder to appreciate the nature or wrongfulness of the conduct.
(2)But a person does not lack criminal responsibility for such conduct if the mental disorder in question consists only of a personality disorder which is characterised solely or principally by abnormally aggressive or seriously irresponsible conduct.
(3)The defence set out in subsection (1) is a special defence.
(4)The special defence may be stated only by the person charged with the offence and it is for that person to establish it on the balance of probabilities.
(5)In this section, “conduct” includes acts and omissions.
(1)A person who would otherwise be convicted of murder is instead to be convicted of culpable homicide on grounds of diminished responsibility if the person’s ability to determine or control conduct for which the person would otherwise be convicted of murder was, at the time of the conduct, substantially impaired by reason of abnormality of mind.
(2)For the avoidance of doubt, the reference in subsection (1) to abnormality of mind includes mental disorder.
(3)The fact that a person was under the influence of alcohol, drugs or any other substance at the time of the conduct in question does not of itself—
(a)constitute abnormality of mind for the purposes of subsection (1), or
(b)prevent such abnormality from being established for those purposes.
(4)It is for the person charged with murder to establish, on the balance of probabilities, that the condition set out in subsection (1) is satisfied.
(5)In this section, “conduct” includes acts and omissions.”.