S2(1)- Homocide Act, as amended by S52 Coroners and Justice Act.
A person who kills/is party to the killing is not to be convicted of murder if he was suffering from an abnormality of mental functioning which:
-Arose from a recgonised medical condition which
-Substantially impairs D's ability to: Exercise self-control, understand the nature of his conduct or form a rational judgement AND provides an explanation for the killing D was party to.
Abnormality of mental functioning- Byrne- 'a state of mind so different to that of an ordinary human being, that the reasonable person would deem it abnormal'.
Recognised medical condition: (medical evidence from two professional psychiatrists).
Wood-Alcohol Dependency Syndrome. Seers- Depression. Martin- Paranoid personality disorder. Ahluwalia- BWS. Tandy- Alcoholism. Dietschmann- even without the drink, he had sufficient abnormality of the mind.
Substantially impairs D's ability to do the three things. Lloyd- 'substantial is less than total impairment, if it is only trvial it is not allowed-it must be substantial'.
Must provide an explanation for D's act/omission- It must be the abnormality of the mind which has caused this; ie there must be a link- it can be the cause or a significant contributory factor- Dietschmann.