Automatism Defence Case Law
🔍 What is Automatism?
Automatism is a defence in criminal law where the defendant claims that they were acting without conscious control or voluntary action at the time of the offence.
It means the defendant’s actions were involuntary — essentially a physical movement without the mind directing it.
If successful, automatism leads to a complete acquittal because the actus reus (voluntary act) is missing.
⚖️ Two Types of Automatism
Insane Automatism (Internal cause)
Caused by a disease of the mind (e.g., epilepsy, diabetes leading to hypoglycemia).
Leads to a special verdict of ‘not guilty by reason of insanity’, which has different legal consequences (usually detention in a hospital).
Non-Insane Automatism (External cause)
Caused by external factors (e.g., blow to the head, sneezing, involuntary intoxication).
Leads to complete acquittal if the defence succeeds.
🔑 Legal Elements to Prove Automatism
The defendant must prove that the act was a total loss of voluntary control.
The cause of automatism must be established — whether internal (insane) or external (non-insane).
Partial loss or impaired control is insufficient.
📚 Important Case Law on Automatism
1. R v. Bratty [1963] AC 386
Facts: Defendant strangled a girl but claimed he was unconscious or in a state of automatism due to a spasm.
Held: The House of Lords distinguished between automatism caused by internal factors (disease of the mind) and external factors. They ruled that if caused by internal disease, it is insanity; if caused by external factors, it is automatism.
Significance:
Established the distinction between insane and non-insane automatism.
Clarified legal tests for automatism.
2. R v. Quick [1973] QB 910
Facts: Defendant, a diabetic on insulin, assaulted a patient while in a hypoglycemic state (low blood sugar).
Held: The court held that hypoglycemia was caused by an external factor (insulin), so it was non-insane automatism.
Significance:
Clarified that automatism caused by external factors like medication is non-insane automatism.
Defendant was acquitted on this basis.
3. R v. Hennessy [1989] 2 WLR 287
Facts: Defendant with diabetes did not take insulin and committed offences while hyperglycemic (high blood sugar).
Held: This was due to an internal factor (the disease itself), so it amounted to insane automatism.
Significance:
Helped define that automatism caused by internal conditions is insanity.
4. R v. Burgess [1991] 2 All ER 769
Facts: Defendant attacked someone during a sleepwalking episode.
Held: The court ruled that sleepwalking was a disease of the mind (internal cause), so it was insane automatism.
Significance:
Extended the disease of the mind concept to some parasomnias (sleep disorders).
5. R v. T [1990] 1 All ER 1
Facts: Defendant was raped and subsequently attacked someone while in a dissociative state.
Held: The court accepted that a psychological blow could cause automatism.
Significance:
Demonstrated that trauma-induced dissociative states could ground automatism.
Established that psychological causes can produce non-insane automatism if external.
6. Attorney-General’s Reference (No 2 of 1992) [1993] 4 All ER 683
Facts: Defendant claimed non-insane automatism after driving dangerously due to a sudden attack of epilepsy.
Held: The court upheld the principle that epilepsy is a disease of the mind; automatism here would be insane automatism.
Significance:
Reinforced epilepsy as internal disease, typically insane automatism.
7. Hill v Baxter [1958] 1 QB 277
Facts: Defendant argued he was not in control of his car after being stung by a swarm of bees.
Held: Court acknowledged situations where involuntary actions (like reflex or unconsciousness) mean no voluntary act was committed.
Significance:
Early authority on the principle of automatism and involuntary acts.
⚖️ Summary Table of Key Automatism Cases
| Case | Year | Cause of Automatism | Type | Outcome/Principle |
|---|---|---|---|---|
| R v. Bratty | 1963 | Internal/external distinction | Both | Established insane vs. non-insane automatism |
| R v. Quick | 1973 | Hypoglycemia (external insulin) | Non-insane | External cause = non-insane automatism acquittal |
| R v. Hennessy | 1989 | Hyperglycemia (internal) | Insane | Internal cause = insanity |
| R v. Burgess | 1991 | Sleepwalking | Insane | Parasomnia = disease of the mind (insane) |
| R v. T | 1990 | Psychological trauma | Non-insane | Trauma can cause automatism |
| AG Ref (No 2 of 1992) | 1993 | Epilepsy | Insane | Epilepsy = disease of mind |
| Hill v. Baxter | 1958 | External factors (bee sting) | Non-insane | Recognised involuntary acts as defence |
🧠 Key Takeaways
Automatism is a complete defence due to lack of voluntary act.
Courts distinguish internal (insane) and external (non-insane) causes.
Internal causes lead to special verdicts and potentially hospital orders.
External causes lead to full acquittal.
Automatism can arise from physical causes (e.g., insulin, bee stings) or psychological states (trauma-induced dissociation).
Defence is rarely successful and requires strong evidence.
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