Automatism is a legal concept used when a person’s actions were involuntary, meaning the act happened without conscious control or choice. In Western Australia, this is most commonly argued under section 23A (Unwilled acts and omissions) of the Criminal Code (WA).
In plain terms, the argument is: the body moved, but the person did not will it, so they should not be held criminally responsible for the act.
If you are facing a criminal charge and automatism may be relevant, it is critical to get legal advice early. These matters often turn on expert evidence and how the court classifies the cause of the involuntary act.
What is automatism?
Automatism refers to involuntary conduct caused by a lack of conscious control or “conscious volition”. Examples often discussed include:
- Sleepwalking
- Epileptic episodes
- Dissociation after physical trauma (for example, severe concussion)
- Drug-related states (in limited circumstances, and depending on how the intoxication occurred)
- Psychological trauma or extreme stress in limited circumstances
A key point is that automatism is not usually treated as a separate “named defence” in WA legislation.
Instead, it is typically raised through the Criminal Code provisions dealing with unwilled acts, and sometimes through the insanity (mental impairment) pathway, depending on what caused the involuntary state.
The WA law behind “sane automatism”: section 23A (unwilled acts)
Section 23A(2) of the Criminal Code (WA) provides that a person is not criminally responsible for an act or omission that occurred independently of the exercise of the person’s will.
Importantly, section 23A is expressly subject to provisions dealing with negligent acts and omissions (including Chapter XXVII and section 444A). That means it will not apply in every situation where someone says they did not act voluntarily.
This is commonly what people mean when they talk about automatism leading to an acquittal in WA.
What the court focuses on
The court is looking at whether the act was voluntary. If the conduct was genuinely unwilled, it undercuts a fundamental part of criminal responsibility.
Sane vs insane automatism: why the distinction matters
Automatism is often discussed in practice in two categories. These labels are used in legal discussion, but they are not headings in the Criminal Code. The Code itself turns on the underlying provisions (most commonly section 23A and section 27).
1) “Sane” automatism (unwilled act, not caused by mental impairment)
“Sane automatism” generally refers to involuntary conduct caused by factors that are not a mental impairment (sometimes described as external factors), such as sleepwalking or concussion.
If successful, the usual outcome is a full acquittal.
2) “Insane” automatism (involuntary act linked to mental impairment)
“Insane automatism” is sometimes used where the involuntary conduct is characterised as linked to mental impairment, meaning the issue moves into the insanity (unsoundness of mind) pathway under section 27 rather than section 23A.
Section 27(1) sets out the test: a person is not criminally responsible on account of unsoundness of mind if, at the time, they were in such a state of mental impairment as to deprive them of capacity to:
- understand what they are doing, or
- control their actions, or
- know that they ought not do the act or make the omission.
Section 27(2) also contains a specific rule dealing with delusions on a specific matter, where the person is not otherwise entitled to the benefit of section 27(1).
If section 27 is established, the outcome is not a standard acquittal in the usual sense. What happens next is governed by WA’s separate mental impairment laws and orders regime, which (as of 1 September 2024) operates under the Criminal Law (Mental Impairment) Act 2023 (WA) (which replaced the older 1996 scheme).
If you want a deeper explanation of the mental impairment pathway, see our related article: Defence of insanity in WA (WN Legal).
Who has to prove what?
If “sane automatism” (section 23A) is raised
Section 23A itself states the rule about unwilled acts, but it does not set out a step-by-step burden of proof framework in its text.
In practical terms, if unwilled conduct is genuinely in issue, the court will closely examine whether the act was voluntary, because voluntariness is central to criminal responsibility. A claim of automatism will usually be tested carefully against the available evidence, including medical material and witness accounts.
If the issue is insanity (section 27)
WA law presumes a person is of sound mind unless proved otherwise.
(Where section 27 is relied on, the court’s approach to how the issue is proved is shaped by the Criminal Code and the broader law governing mental impairment matters, as applied to the facts of the case.)
Psychological blow (trauma-induced) automatism
One of the more complex areas is trauma-induced automatism, sometimes described as “psychological blow” automatism. WA commentary outlines several features courts look for, including:
- external events constituting the trauma
- the automatism being transient and unlikely to recur
- the trauma being capable of affecting a “reasonable person” in a similar situation
- the trauma being more severe than ordinary life stress
Because this category can sit close to mental impairment issues, the classification (s 23A vs s 27) can become a major battleground in contested matters.
Drug-related states and intoxication: a necessary caution
If a drug-related state is raised as part of an automatism argument, it is important to separate:
- situations where intoxication or stupefaction occurred without intention, and
- situations where a person intentionally caused themselves to become intoxicated or stupefied.
This matters because section 28 provides that section 27 applies where the mind is disordered by intoxication or stupefaction caused without intention, and that section 27 does not apply where the person intentionally caused themselves to become intoxicated or stupefied.
What evidence is usually needed?
Automatism is rarely accepted on assertion alone. Courts typically expect strong supporting evidence, often including expert reports, and careful analysis of what caused the loss of control and whether it was foreseeable.
Common evidence issues include:
- medical history and treating notes (where relevant)
- expert opinion addressing the involuntary state
- witness accounts of the person’s behaviour before, during, and after the event
- whether there is an underlying condition that shifts the case into mental impairment territory
Common misconceptions about automatism
“Automatism is an easy way to get off a charge”
It is not. Automatism is heavily scrutinised, and the cause of the involuntary act is often contested. The defence usually needs significant evidence and can involve expert witnesses.
“If it’s involuntary, it’s always section 23A”
Not necessarily. If the involuntary conduct is found to be linked to mental impairment, the case may shift to the section 27 insanity framework, with very different legal consequences.
Defence Example and Case Review: R v Falconer (1990) 171 CLR 30; [1990] HCA 49
This is one of the leading Australian cases on automatism and voluntariness. It is regularly cited because it explains how a dissociative state (sometimes described as a “psychological blow”) can be relevant to whether an accused person’s act was willed, and therefore whether criminal responsibility can attach at all.
Background
- Charge: Mary Sandra Falconer was convicted in the Supreme Court of Western Australia of the wilful murder of her husband.
- Defence argument: Mrs Falconer sought to rely on psychiatric evidence to support that, at the time of the shooting, she was in a dissociative state relevant to the question of whether the shooting was a willed act (in other words, whether the act was voluntary).
- Key context (as described in the case materials):
- There was a history of serious marital conflict, including domestic violence and allegations of sexual abuse of their daughters.
- On the day of the incident (on her account), her husband entered unexpectedly, sexually assaulted her, taunted her, and reached for her hair.
- She said she remembered nothing from that point until she found herself on the floor with the shotgun and her husband dead nearby.
- At trial, the judge did not allow her to call the psychiatric evidence.
Court’s findings
The High Court did not decide that Mrs Falconer was acting in automatism as a fact. Instead, it dealt with what the jury should have been allowed to consider.
The High Court held, in substance, that:
- The psychiatric evidence should have been admitted, because it was relevant to the issue of voluntariness (whether the act was “willed”).
- The WA Court of Criminal Appeal was correct to quash the conviction and order a retrial, because excluding that evidence prevented the defence case on voluntariness from being properly left to the jury.
- The High Court therefore dismissed the Crown’s attempt to restore the original conviction (special leave was granted, but the appeal was dismissed).
Legal principles highlighted
This case is used as a teaching and “example” case because it clarifies several key points.
1) Automatism is really about voluntariness
Courts often use “automatism” as a convenient label, but the legal question is whether the relevant act was willed.
2) Voluntariness involves consciousness and choice
The materials commonly cited from Falconer emphasise that “will” imports consciousness of the nature of the act and a choice to do an act of that nature.
3) Dissociation after severe psychological trauma can be capable of supporting “sane” automatism
Falconer is frequently cited for the idea that a temporary or transient dissociative state after severe emotional shock or psychological trauma can, in some circumstances, be treated as consistent with sane automatism, depending on the evidence.
4) If the evidence could point to either “sane” or “insane” automatism, it may need to be left to the jury
Modern jury direction resources use Falconer for the proposition that where there is evidence of automatism that may be explained either by a non-mental impairment cause (sane) or by a mental impairment cause (insane), the judge may need to leave that classification issue to the jury.
5) Expert evidence can be central
Falconer is also a practical warning: if expert psychiatric evidence is relevant to voluntariness, excluding it can amount to a serious error because it prevents the defence case from being properly tested by the jury.
How WN Legal can help
If you have been charged and believe your actions were not voluntary, early advice matters. The way the case is framed, including whether it is treated as unwilled conduct (s 23A) or mental impairment (s 27), can significantly affect the strategy and potential outcomes.
You can also explore our related WA defence guides:
