Criminal liability can be affected by mental illness or disability in limited ways such as the insanity defense or diminished responsibility defense for murder charges. The insanity defense examines whether due to a disease of the mind, the defendant did not know the nature or quality of their act, or did not know the act was wrong. Epilepsy, diabetes, and other conditions have been found to potentially constitute a disease of the mind if they cause involuntary acts. However, the concepts of insanity and disease of the mind are narrowly defined in criminal law. Reform efforts have sought to broaden defenses related to mental conditions.

1. Criminal Law
Automatism and Mental
Illness

2. Mental Disability
 Many defendants will be suffering from learning disabilities or
some form of mental illness. Does this affect their criminal
liability?
 very limited impact on liability except for:
 defence of ‘insanity’
• anachronistic conceptual framework
 defence of ‘diminished responsibility
• only for murder
 more likely to affect sentencing

3. The ‘voluntary’ act
 Another general principle:
 actus reus must be ‘voluntary’ - defendant must have been
exercising free choice in committing the crime
 for example, look at the defences of justified force/self defence or
duress
 rationale: unjust to punish where D unable to exercise free choice
 But this issue must be raised by D - presumption that act is
voluntary

4. Automatism
 General principle of volition:
 can arise as a defence with automatism. Criteria are:
 D acts involuntarily: eg concussed, under administration of
anaesthetic, psychological trauma or blackout
• Hill v Baxter 1957 - claimed accident was result of ‘blackout’ - Divisional Court
agreed that automatism could be a defence but required an evidential basis
 complete [not just reduced] destruction of voluntary control
• AG’s Ref 2/92 - trance induced by featureless motorway not sufficient

5. Automatism
Automatism as a defence can be of two types:
resulting a) from mental illness b) not from mental illness
 Non-insane  Insane automatism:
automatism:
 result of mental
 not the result of disorder
mental disorder
 unfettered acquittal  special verdict

6. ‘Insane automatism’: procedure
 M’Naghten’s Case 1843 - Tindal lays down elements of defence
 ‘every man is presumed to be sane….until the contrary be proved’
 burden of proof on accused
• but Lambert [2001] 3 All ER 577
 fitness to plead - s.2 Criminal Procedure (Insanity) Act 1991: Antoine
[2000] 2 All ER 208; H (2004) 1 All ER 412
• did D do act charged? was he under a disability?
 special verdict: Trial of Lunatics Act 1883 as amended by s.1 Criminal
Procedure Act 1964
 discretion on sentence: 1991 Act

7. Defence of ‘Insanity’: substance
 Elements of defence in Tindal CJ’s judgment in M’Naghten’s
Case 1843
 accused must prove (on the balance of probabilities) that he was
suffering from:
 a defect of reason
 resulting from a disease of the mind
 with the consequence that:
• D did not know nature or quality of act OR
• D did not know the act was wrong

8. ‘Disease of the mind’
 ‘Insane automatism’ - involuntary act must be shown to be due
to ‘disease of the mind’
 ‘disease of the mind’ marks boundary between sane and insane
automatism
 insanity and ‘disease of the mind’ are legal (not medical) concepts
 Note: criminal law does not follow s.1(2), Mental Health Act 1983
• ‘mental disorder’ means mental illness, arrested or incomplete development
of the mind, psychopathic disorder and any other disorder or disability of
the mind

9. ‘Disease of the mind’
 Legal concept of ‘insanity’ means:
 D can come within Mental Health Acts and still be
criminally responsible: eg psychopaths
 D can come outside Mental Health Acts and still be
regarded as raising defence of insanity rather than
non-insane automatism: epileptics

10. ‘Disease of the mind’
 Consider Kemp 1957:
 suffering from arteriosclerosis and attacked wife
with hammer
 the question was whether the mental faculties of
reason, understanding and memory had been
impaired - if so, disease of the mind and irrelevant ‘…
whether the condition…is curable or incurable,
transitory or permanent’ (Devlin)

11. Epilepsy as ‘insanity’
Consider Bratty 1963:
 epileptic strangles girl in psycho-motor episode -
judge leaves only issue of insanity to jury – conviction
upheld by House of Lords
 ..any mental disorder which has manifested itself in
violence and is prone to recur is a disease of the mind.
At any rate it is the sort of disease for which a person
should be detained in hospital rather than be given an
unqualified acquittal(Denning)

12. Epilepsy as ‘insanity’
 Bratty upheld in Sullivan 1983:
 epileptic attacks friend during epileptic fit - judge rules this
is defence of insanity - upheld by House of Lords
 ..it matters not whether the aetiology of the impairment is
organic..or functional, or whether the impairment is transient and
intermittent… The purpose of the legislation…has been to protect
society against recurrence of dangerous conduct. (Diplock)
 Diplock suggests that ‘external’ factor causing impairment
[blow to head, reaction to anaesthetic] is not ‘disease of the
mind’

13. Breadth of ‘insanity’
 Should an epileptic be treated as ‘mad’?
 judgments suggest that policy considerations (future
danger) are uppermost in defining ‘disease of the mind’.
 Other illnesses:
 internal/external factor approach by Diplock in Bratty
 leads to sleepwalkers (Burgess 1991) and diabetics being
classed as ‘mad’

14. Diabetes as ‘insanity’
 If diabetics fail to take insulin or to eat, drink too
much or get over-tired:
 hypoglycaemia - deficiency in blood sugar levels - too
much insulin for blood sugar levels to cope with
 hyperglycaemia - deficiency of insulin and excess of
blood sugar levels
 Sufferer can become violent and incapable of control

15. Diabetes as ‘insanity’
 Consider Quick 1973:
diabetic, took insulin but drank and didn’t eat. Assaulted patient in his
care
 pleaded guilty when judge ruled that this was defence of
insanity
 Court of Appeal quashes conviction:
a malfunctioning of the mind of transitory effect caused by the
application to the body of some external factor such as violence,
drugs…., alcohol and hypnotic influences cannot fairly be said to be
due to disease (Lawton)

16. Diabetes: external or internal factor?
 Emphasis on ‘external factors’
reinforced in Sullivan, Hennessy 1989,
Bingham 1991
 overdose of insulin - external factor -
acquittal?
 failure to take insulin - internal factor -
hospital order?

17. Diabetes: self-induced?
 In Quick, Lawton raised additional issue:
 ….a self-induced incapacity will not excuse…nor will
one which could have reasonably been foreseen….
 In Bailey 1983, Court of Appeal disapproved of
this - self-induced incapacity could be a
defence except where induced by alcohol or
proscribed drugs.

18. Defect of Reason
 In Clarke 1972:
 shoplifting, plea of non-intent but absent-minded.
Doctor gave evidence of depression - judge ruled that
this was plea of insanity!
 Court of Appeal disapproved of this - even if
depression was ‘disease of the mind’,
forgetfulness is not a defect of reason.

19. Nature or Quality of Act
 Shows extreme level of functional impairment required:
 refers to physical nature of act and excludes irresistible
impulse or uncontrollable desire even if emanating from
mental illness
 excludes psychopaths - Sutcliffe (Yorkshire Ripper)
 ‘The mere fact that a man thinks he is John the Baptist
does not entitle him to shoot his mother’ (Hewart LCJ)

20. ‘Not knowing it was wrong’
 Alternative to not knowing the nature of
act
 ButD must believe it is not legally
wrong, not simply that it was morally
wrong
 Windle 1952

21. Reform
 Butler Committee on Mentally Disordered Offenders
(Cmnd 6244)
 recommended verdict of not guilty on evidence of mental
disorder (paras 18.14-18.36)
 broader defence of non-insane automatism in clauses 33
and 34
 Disposal recommendations implemented in 1991 Act