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The medicolegal aspects of automatism in mild head injury
  1. P McCrory
  1. Neurologist & Sports Physician 31 Grosvenor Parade, Balwyn Victoria 3103, Australia pmccrory{at}

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    Automatism or automatic behaviour was originally described in the Hippocratic corpus in relation to sleepwalking and other nocturnal behaviours.1 Despite its long history, this area of automatism remains confused and imprecise in the medical and legal literature. Within English common law, it is a fundamental principle that the intent (mens rea) and the act (actus reus) must occur together to constitute the crime.2 As such, the absence of a mens rea means that the person at that point in time lacks the intent to commit a crime.

    In the legal view, post-traumatic automatism is a form of “sane” automatism because it results from an external factor, for example, a blow to the head, rather than from a disease of the mind (which is responsible for “insane” automatisms).3, 4 As a legal defence under English law, if successful, post-traumatic automatism leads to acquittal rather than the judge deciding the disposal as in the case of insane automatism.5

    In recent years, a number of cases of footballers appearing before disciplinary tribunals for striking and other charges have claimed in their defence that they suffered a prior concussive injury and at the time of the alleged incident were suffering from a “post-traumatic automatism” and as a result were not responsible for their actions. In one celebrated case in Australian football, this defence was successful and resulted in the sport's administrative body developing specific guidelines to outlaw this potential defence. This topic of post-traumatic automatism has only a limited amount of published information to guide practitioners, players, administrators, and lawyers and this paper seeks to establish appropriate medical guidelines in this area.

    The medical view of post-traumatic automatism

    Automatism may be defined as “the existence in any person of behavior of which he is unaware and over which he has no conscious control”.6 It has also been defined without reference to consciousness simply as “... involuntary movement of the limbs or body of a person ...”.7 Post-traumatic automatism implies the presence of a head injury and subsequent amnesia for the automatic events that occur during its existence.

    Fenwick more specifically defines automatism as “an involuntary piece of behavior over which the individual has no control. The behavior is usually inappropriate to the circumstances and may be out of character for the individual. Afterward the individual may have no recollection ... of his actions ...”.7

    Although the definition of automatism has been established, in the setting of head injury it implies a disturbance of consciousness that is often imprecise in nature. Normal consciousness necessitates an intricate and complex relation between the various components of the brain and the environment. The limits of consciousness are hard to define satisfactorily and quantitatively and we can only infer self awareness in others by their appearance and their acts.

    The legal view of post-traumatic automatism

    Although the medical and English legal definitions of automatism differ slightly,7 in courtrooms the legal one clearly takes precedence. The most accepted legal definition is that given by Viscount Kilmuir LC in the House of Lords appeal in the case of Bratty v Attorney General for Northern Ireland. This case involved a defence of automatism caused by epilepsy. He ruled that “... the state of a person who though capable of action, is not conscious of what he is doing ... it means unconscious, involuntary action and it is a defense because the mind does not go with what is being done ...”. In the same case, Lord Denning said: “... no act is punishable if done involuntarily and an involuntary act in this context ... means an act which is done by muscles without any control by the mind ... a reflex action ... or an act done by a person who is not conscious of what he is doing, such as an act done whilst suffering a concussion . . . However to prevent confusion it is to be observed that in the criminal law an act is not to be regarded as an involuntary act simply because the actor does not remember it ...” (Bratty v Attorney General for Northern Ireland: [1961] 46 Cr. App. R. 1, 7, 8. AC 401)

    Traumatic brain injury and concussion

    Traumatic brain injury encompasses a spectrum of injury ranging from mild to severe. This injury spectrum is usually subdivided according to the Glasgow Coma Score, which is a standardised score administered at six hours post-injury.8 A mild injury would score 13–15, a moderate injury 8–12, and a severe injury <8. This scale is largely dependent on the patient's level of conscious state. Consumption of alcohol may be a confounding factor in accurately assessing such a scale.

    Mild brain injury may be subclassified further and the term “concussion” is often used to describe the mild end of this injury subtype. Such injuries are commonly seen in sport, following falls or assaults, and after motor vehicle crashes. It is important therefore to clarify what is meant by concussion and how the behaviour of such a patient reflects the clinical stages of recovery from such an injury.

    The Committee on Head Injury Nomenclature of the Congress of Neurological Surgeons has developed a definition of concussion. The American Medical Association and the International Neurotraumatology Association have subsequently endorsed this “consensus” definition of concussion, which has now become the accepted definition by most researchers in this field.9, 10 The Congress of Neurological Surgeons definition states that concussion is “... a clinical syndrome characterised by the immediate and transient post-traumatic impairment of neural function such as alteration of consciousness, disturbance of vision or equilibrium due to mechanical forces”.

    The clinical “stages” of concussion

    There is a relatively limited range of clinical symptoms and psychological effects that is seen following a concussive injury. The subject usually passes through a series of stereotyped stages of recovery.11 The typical sequence of recovery from a concussive injury would be as follows:

    Stage 1: Immediately post-injury

    —There may be a period of unconsciousness for seconds or minutes but the subject usually awakens spontaneously. On waking, there may be little in the way of retrograde memory disturbance (that is, memory loss prior to the accident) although this becomes more prominent in the ensuing minutes to hours. The subject may be unsteady if attempting to stand. If questioned the subject will appear confused and disorientated. He or she will not be capable of responding to questions or commands. If an observer approaches the subject in this phase, the subject usually repetitively says “what happened” every few seconds and is incapable of understanding any explanation. Some purposeless motor activity may be present. This motor phenomenon is often termed “cerebral irritability”. This stage lasts for a variable period of time but generally has recovered by 20 to 30 minutes post-injury. In the stage of post-traumatic amnesia, a subject may show automatisms.

    Stage 2: Following recovery of post-traumatic amnesia

    —Once the period of acute post-traumatic amnesia has resolved (over 20–30 minutes) the subject is then capable of responding to command, is orientated to time, place, and person, and will be able to remember information presented to him. Any unsteadiness will have resolved by this time. The subject may report headache, blurred vision, and/or nausea at this time. Headache is a universal although non-specific symptom post-injury. If neuropsychological testing is performed at this time, characteristic deficits such as slowed information processing, will be evident.

    Stage 3: Clinical recovery

    —The acute symptoms (headache, nausea, etc) settle over several days. During this period, the memory functions normally although the subject continues to show deficits on formal neuropsychological testing. Such deficits may not be obvious to an observer or often to the patients themselves.

    Stage 4: Cognitive recovery

    —The clinical symptoms have fully resolved by this time and the neuropsychological function returns to normal over a variable period, depending upon the severity of injury, but typically would vary from 3–4 days for a mild concussion up to 2–3 weeks for a severe concussion.

    Ritchie Russell12 made a number of observations about the clinical phenomenon of concussion and automatic behaviour. He described a stage of “cerebral irritation” that: “... is seen in all degrees of concussion. The concussed football player often moves his limbs restlessly or talks meaninglessly, and not a few cases of head injury are violent and abusive when seen in the outpatient department. Though in slight injuries, the duration of this stage is brief when compared to what may be seen in severe cases, it seems that the condition has the same significance in both types of case. In the stage of irritability, consciousness is not fully recovered and the patients have no subsequent recollection of their actions. It is probable that these irritable states merely represent a stage in the recovery of consciousness. The mental and higher cerebral functions have not yet recovered, and owing to the lack of their control, the more primitive and less vulnerable motor activity is running wild ...”

    In medical parlance, Russell's concept of “cerebral irritability” reflects the legal parlance of a post-traumatic automatism.

    Automatism in the setting of concussion

    Although not well studied in this setting, the consensus of expert opinion would regard “automatism” or irritability following concussion to be typically manifest by signs such as:

    • Thrashing or flailing limbs in a non-directed manner

    • Refusing to be directed (for example, onto a stretcher or into an ambulance)

    • Wildly swinging arms if directly confronted or restrained

    • Aimless wandering in a “robotic” fashion.

    Furthermore, any automatisms by definition could only occur during the phase of post-traumatic amnesia following the trauma. This period usually resolves over 20–30 minutes following a typical concussive injury. Post-traumatic automatisms do not encompass goal directed or purposeful activity. The typical occurrence is a concussed footballer rolling about on the ground or attempting to try and get up and who is incapable of following directions to get onto a stretcher. If such a player does get to his feet an observer may describe them as resembling a robot or automaton staggering around but with no purpose.13 In many ways, the increasing complexity of behaviour directly reflects more specific intent in that specific activity.

    In practice, establishing a defence of post-traumatic automatism depends largely on a thorough knowledge of the clinical and neuropsychological features of mild brain injury, clinical assessment, and review of the evidence. Transcripts of witness statements, police interviews, especially if video or audiotaped, and contemporaneous notes by police or medical staff often provide the most useful sources of information on which an opinion in this regard may be based.

    The criteria that would need to be established to prove a defence of epileptic automatism were originally proposed by Fenwick7 and modified by Wright and colleagues.14 In this paper, we propose a more comprehensive requirement specifically for post-traumatic automatism. This should include:

    1. The presence of a documented concussive brain injury

    2. The automatism occurring in the stage of post-traumatic amnesia (Stage 1 above) as evidenced by documentation of post-traumatic amnesia or impaired memory for new learning

    3. The automatism behaviour represents a reactive and/or purposeless response to stimulation or confrontation

    4. No premeditation, planning, or concealment is demonstrable

    5. The absence of goal directed, purposeful, or proactive behaviour.

    The usefulness of forensic psychiatric examinations is limited in this setting.15, 16 In the absence of intent due to post-traumatic automatism, psychiatric determination of the person's state of mind adds little to this process. Psychiatrists seldom have clinical experience of acute head injury and are ill equipped to judge the neurological aspects of this problem. Although the psychiatrist may correctly concern himself with the individual's capacity to form intent, nevertheless in the case of post-traumatic automatism, this is not usually relevant. Intent is not a psychiatric concept.17 In court, the issue of intent is usually left to the jury to determine (see R v Maloney [1985] AC 905, [1985] 1 All ER 1025, [1985] 2 WLR 648).


    The issue of post-traumatic automatisms is complex, with different legal and medical views on the subject. Although the phenomenon of automatic behaviour is well established following epileptic seizures or in the setting of sleepwalking or other nocturnal parasomnias, the issue of post-traumatic automatisms is complex as the issue depends on a characterisation of the individual's conscious state and the stage of concussion they were in at the time of the alleged behaviour. This paper seeks to establish guidelines for the assessment of this phenomenon.


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