Voluntary manslaughter - Diminished responsibility

Partial defence to murder - reduces from murder to vol manslaughter. 

'An abnormality of mental functioning  from a recognised medical condition which provides an explanation for the killing and which substantially impairs D's ability to 
a) form a rational judgement 
b) excersice self control 
c) know the nature of their conduct 

Abnormality of mental functioning from a recognised medical condition 
AOMF = inability to exercise power and control - R V Byrne 

Recognised medical condition
- ADS Tandy 
- Epilepsy - Cambell 

Must be an internal source - no intoxication unless it causes long term internal damage. 
eg: Tandy - alcohol dependency syndrome 

a) understand nature of conduct 
b) exersise self control 
c) form a rational judgement 
R V Campbell