Automatism And Mental Disorder Defenses
🔍 Key Difference: Automatism vs. Insanity
| Defence | Definition | Legal Consequence |
|---|---|---|
| Automatism | Acts done without voluntary control due to an external factor | Full acquittal |
| Insanity | Acts done due to a disease of the mind affecting reasoning ability | "Not guilty by reason of insanity" – may lead to hospital order or other outcomes |
Part 1: Automatism – Detailed Explanation & Case Law
✅ 1. R v. Bratty [1963] AC 386
Facts:
Defendant strangled a girl during an epileptic seizure and claimed he had no control over his actions.
Judgment:
The House of Lords held that for automatism to succeed, there must be total loss of voluntary control.
Significance:
This case defined automatism and ruled that if the cause is internal (like epilepsy), it falls under insanity instead.
✅ 2. R v. Quick [1973] QB 910
Facts:
A nurse assaulted a patient while suffering a hypoglycaemic episode (low blood sugar), caused by insulin treatment.
Judgment:
Court ruled this was automatism caused by an external factor (insulin), not insanity.
Significance:
Clear distinction: hypoglycaemia = automatism, because it results from medication, not the disease itself.
✅ 3. R v. T [1990] Crim LR 256
Facts:
Defendant committed robbery after a traumatic event (rape), and claimed it caused a dissociative state.
Judgment:
Trial judge allowed automatism to go to jury.
Significance:
Established that severe psychological trauma could — in exceptional cases — be treated as an external factor.
✅ 4. R v. Bailey [1983] 1 WLR 760
Facts:
Diabetic defendant failed to eat after insulin, leading to violent behaviour. Claimed automatism.
Judgment:
Court held that self-induced automatism may not be a defence if the risk was foreseeable.
Significance:
Introduced limitation: If D is reckless (e.g., failing to eat after insulin), automatism may not apply.
Part 2: Insanity (Mental Disorder Defence) – Detailed Explanation & Case Law
✅ 5. M’Naghten’s Case (1843) 10 Cl & Fin 200
Facts:
Daniel M’Naghten shot and killed the Prime Minister’s secretary, thinking he was being persecuted.
Judgment:
House of Lords established the M'Naghten Rules, the foundation for the insanity defence.
M'Naghten Rules:
Defect of reason
From disease of the mind
So the defendant didn’t know the nature/quality of the act OR didn’t know it was wrong
Significance:
Still forms the legal test for insanity in UK law.
✅ 6. R v. Kemp [1957] 1 QB 399
Facts:
Defendant attacked wife during a blackout caused by hardening of arteries affecting the brain.
Judgment:
Held to be insanity: medical cause was internal, affecting the mind.
Significance:
Clarified that “disease of the mind” can include physical illness affecting mental function.
✅ 7. R v. Sullivan [1984] AC 156
Facts:
Epileptic seizure caused defendant to injure a neighbour. Defence of insanity raised.
Judgment:
Court held epilepsy = internal cause = insanity.
Significance:
Even temporary conditions can count as insanity if the cause is internal.
✅ 8. R v. Hennessy [1989] 1 WLR 287
Facts:
Diabetic defendant failed to take insulin and committed an offence in a disoriented state.
Judgment:
Court held it was insanity (internal condition), not automatism.
Significance:
Distinguished from Quick – if the cause is the illness (not the treatment), it’s insanity.
Summary Table
| Case Name | Defence Type | Key Principle |
|---|---|---|
| Bratty (1963) | Automatism | Defined automatism as total lack of control |
| Quick (1973) | Automatism | External factor (insulin) = automatism |
| T (1990) | Automatism | Trauma may be external factor |
| Bailey (1983) | Automatism | Self-induced automatism may be excluded |
| M’Naghten (1843) | Insanity | Created the legal test for insanity |
| Kemp (1957) | Insanity | Physical condition affecting mind = insanity |
| Sullivan (1984) | Insanity | Epilepsy = internal = insanity |
| Hennessy (1989) | Insanity | Illness (not treatment) = insanity |
🧠 Key Takeaways
Automatism = total loss of control from external cause (e.g., insulin, trauma).
Insanity = defective reasoning from internal disease of the mind (e.g., epilepsy, diabetes).
Bratty and M’Naghten are cornerstone cases.
Quick vs. Hennessy is a great comparison: same illness, different causes = different defences.
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