R v T [1990] Crim LR 256
Criminal Law – Automatism – Defences – Post-traumatic Stress – Insanity
Facts:
T was one of three defendants charged with armed robbery. Upon arrest, T could only recall some of the events that had occurred. Several days later, she was found to have been raped three days prior to her arrest but had not reported it. She was diagnosed with Post Traumatic Stress Disorder (PTSD) and submitted a defence of non-insane automatism.
Issues:
Whether the defence of non-insane automatism was available. Whether rape was an “external factor” that caused a malfunction of T’s mind.
Held:
There had been no previous case in which an incident of rape had been held to be “an external factor” causing a malfunctioning of the mind within the definition of insanity. However, rape was an extraordinary external event that would likely have an appalling effect on the average person and satisfied the requirement of an “external factor”. PTSD causing someone to act in a particular way was not a disease of the mind in itself, even if there was a delay between the act and the state of disconnection that manifested. The court considered that T had been acting in a “dream” like state, which could be considered automatism within the definition. If T was held to be acting in an automatist state, the court were left to determine whether such a state had been caused by external factors. The case of R v Rabey (1981) 79 Dominion Law Reports 435 (Ontario Court of Appeal) was distinguished on the basis that the external factor constituted nothing more than the “ordinary stresses and disappointments of life” [79], whereas T had suffered a severe assault which would have affected any ordinary person.
Updated 20 March 2026
This case summary accurately describes the decision in R v T [1990] Crim LR 256 and the legal principles applied at the time. The core distinction between insane and non-insane automatism, and the relevance of an external factor to that distinction, remains part of English criminal law.
However, readers should be aware of significant subsequent developments. The Law Commission has long criticised the M’Naghten-based insanity rules and the insane/non-insane automatism divide as unprincipled and outdated. Its 2023 report Reforming the Law on Mental Incapacity Defences in Criminal Law (Law Com No 413) proposes substantial reform to both the insanity defence and automatism, including abolishing the disease of the mind / external factor distinction in its current form, though these recommendations have not yet been enacted. The law as described in the article therefore remains technically current as a matter of enacted law, but it exists in an area widely expected to be subject to legislative reform. Students should consult up-to-date textbooks and the Law Commission’s report alongside this summary.
