Automatism, as the name suggests, deals with circumstances where the actions of the accused were not "willed"; that is to say, not a voluntary act.
Reference is frequently made to M'Naghten's case  UKHL J16, where the UK House of Lords set out what came to be known as the M’Naghten Rules. These rules hold that a person wishing to rely on the defence of insanity (as the defence was then known)must show:
They laboured under a defect of reason
Caused by a disease of the mind; so that either
He did not know the nature and quality of his acts, or that he did not know what he was doing was wrong.
These rules have found particular application in cases where the accused claims he or she acted on “reflex” (such as was claimed in Ryan v R  HCA 2), where the defendant claims to have “transient mental malfunction of his otherwise sound mind“ (as was claimed in R v Falconer  HCA 49), or in cases of somnambulism (as was claimed in R v DB  NSWCCA 87
The position was codified by the passing of the Mental Health (Forensic Provisions) Act 2020. Section 28 provides a defence of mental health impairment or cognitive impairment:
(1) A person is not criminally responsible for an offence if, at the time of carrying out the act constituting the offence, the person had a mental health impairment or a cognitive impairment, or both, that had the effect that the person—
(a) did not know the nature and quality of the act, or
(b) did not know that the act was wrong (that is, the person could not reason with a moderate degree of sense and composure about whether the act, as perceived by reasonable people, was wrong).
(2) The question of whether a defendant had a mental health impairment or a cognitive impairment, or both, that had that effect is a question of fact and is to be determined by the jury on the balance of probabilities.
(3) Until the contrary is proved, it is presumed that a defendant did not have a mental health impairment or cognitive impairment, or both, that had that effect.
M'Naghten's case  UKHL J16
“And as these two questions appear to us to be more conveniently answered together, we have to submit our opinion to be, that the jurors ought to be told in all cases that every man is to be presumed to be sane, and to possess a sufficient degree of reason to be responsible for his crimes, until the contrary be proved to their satisfaction; and that to establish a defence on the ground of insanity, it must be clearly proved that, at the time of the committing of the act, the party accused was labouring under such a defect of reason, from disease of the mind, as not to know the nature and quality of the act he was doing; or, if he did know it, that he did not know he was doing what was wrong.”
Stapleton v R  HCA 56
“it is desirable to say that if a jury were to lay hold of this point that the accused must be incapable of understanding that he was acting contrary to law as distinguished from appreciating that his act was wrong according to the ordinary standards adopted by reasonable men, the distinction would tell against the appellant.”
Ryan v R  HCA 2
“That a crime cannot be committed except by an act or omission of or by the accused is axiomatic. It is basic, in my opinion, that the "act" of the accused, of which one or more of the various elements of the crime of murder as defined must be predicated must be a "willed", a voluntary act which has caused the death charged. It is the act which must be willed, though its consequences may not be intended.”
R v Falconer  HCA 49
“Although the prosecution bears the ultimate onus of proving beyond reasonable doubt that an act which is an element of an offence charged was a willed act or, at common law, was done voluntarily… the prosecution may rely on the inference that an act done by an apparently conscious actor is willed or voluntary to discharge that onus unless there are grounds for believing that the accused was unable to control that act.”
Hawkins v R  HCA 28
“Evidence of mental disease that is incapable of supporting a finding of insanity or that does not satisfy the jury that the accused was insane when the incriminated act was done, is inadmissible on, and must be taken to be irrelevant to, the issue whether the act was "voluntary and intentional" within the meaning of those terms…”
R v DB  NSWCCA 87
"It is also a mistake to ask whether a parasomnia such as sexsomnia, unaccompanied by other psychopathology, constitutes a disturbance of volition. The labels parasomnia and sexsomnia, like somnambulism, describe the phenomena of a person performing, while asleep, various acts usually associated with willed behaviour of an awake person; they do not describe a person lacking while asleep the volition which every person lacks while asleep. The true issue is not whether sexsomnia is a mental health impairment, but whether the respondent had a disturbance of volition within s 4(1)(a). That issue is not assisted by argument over whether sexsomnia is a physiological or psychological disorder. Whatever accounts for the acts of the sleepwalker, it is not a lack of volition, but presumably the action of the subconscious mind."
That if the accused was conscious that the act was one which he ought not to do; and if the act was at the same time contrary to law, he is punishable. In all cases of this kind the jurors ought to be told that every man is presumed to be sane, and to possess a sufficient degree of reason to be responsible for his crimes, until the contrary be proved to their satisfaction: and that to establish a defence on the ground of insanity, it must be clearly proved that at the time of committing the act the party accused was labouring under such a defect of reason, from disease of the mind, as not to know the nature and quality of the act he was doing, or as not to know that what he was doing was wrong.
The prisoner had been indicted for that he, on the 20th day of January 1843, at the parish of Saint Martin in the Fields, in the county of Middlesex, and within the jurisdiction of the Central Criminal Court, in and upon one Edward Drummond, feloniously, wilfully, and of his malice aforethought, did make an assault; and that the said Daniel M'Naghten, a certain pistol of the value of 20s., loaded and charged with gunpowder and a leaden bullet (which pistol he in his right hand had and held), to, against and upon the said Edward Drummond, feloniously, wilfully, and of his malice aforethought, did shoot and discharge; and that the said Daniel M'Naghten, with the leaden bullet aforesaid, out of the pistol aforesaid, by force of the gunpowder, etc., the said Edward Drummond, in and upon the back of him the said Edward Drummond, feloniously, etc. did strike, penetrate and wound, giving to the said Edward Drummond, in and upon the back of the said Edward Drummond, one mortal wound, etc., of which mortal wound the said E. Drummond languished until the 25th of April and then died; and that by the means aforesaid, he the prisoner did kill and murder the said Edward Drummond. The prisoner pleaded Not guilty.
Lord Chief Justice Tindal (in his charge)
The question to be determined is, whether at the time the act in question was committed, the prisoner had or had not the use of his understanding, so as to know that he was doing a wrong or wicked act. If the jurors should be of opinion that the prisoner was not sensible, at the time he committed it, that he was violating the laws both of God and man, then he would be entitled to a verdict in his favour: but if, on the contrary, they were of opinion that when he committed the act he was in. a sound state of mind, then their verdict must be against him.
Mr. Justice Maule
The first question, as I understand it, is, in effect, What is the law respecting the alleged crime, when at the time of the commission of it, the accused knew he was acting contrary to the law, but did the act  with a view, under the influence of insane delusion, of redressing or revenging some supposed grievance or injury, or of producing some supposed public benefit?-If I were to understand this question According to the strict meaning of its terms, it would require, in order to answer it, a solution of all questions of law which could arise on the circumstances stated in the question, either by explicitly stating and answering such questions, or by stating some principles or rules which would suffice for their solution. I am quite unable to do so, and, indeed, doubt whether it be possible to be done; and therefore request to be permitted to answer the question only so far as it comprehends the question, whether a person, circumstanced as stated in the question, is, for that reason only, to be found not guilty of a crime respecting which the question of his. guilt has been duly raised in a criminal proceeding? and I am of opinion that he is not. There is no law, that I am aware of, that makes persons in the state described in the question not responsible for their criminal acts. To render a person irresponsible for crime on account of unsoundness of mind, the unsoundness should, according to the law as it has long been understood and held, be such as rendered him incapable of knowing right from wrong. The terms used in the question cannot be said (with reference only to the usage of language) to be equivalent to. a description of this kind and degree of unsoundness of mind. If the state described in the question. be one which involves or is necessarily connected with such an unsoundness, this is not a matter of law but of physiology, and not of that obvious and familiar kind as to be inferred without proof.
Lord Chief Justice Tindal
My Lords, Her Majesty's Judges (with the exception of Mr. Justice Maule, who has stated his. opinion to your Lordships), in answering the questions proposed to them by your Lordships' House, think it right, in the first place, to state that they have forborne entering into any particular discussion upon these questions, from the extreme and almost insuperable difficulty of applying those answers to cases in which the facts are not brought judicially before them. The facts of each particular case must of necessity present themselves with endless variety, and with every shade of difference in each case; and as it is their duty to declare the law upon each particular case, on facts proved before them, and after hearing argument of counsel thereon, they deem it at once impracticable, and at the same time dangerous to the administration of justice, if it were practicable, to attempt to make ninute applications of the principles involved in the answers given by them to your Lordships' questions.
The first question proposed by your Lordships is this:" What is the law respecting alleged crimes committed by persons afflicted with insane delusion in respect of one or more particular subjects or persons: as, for instance, where at the time of the commission of the alleged crime the accused knew he was acting contrary to law, but did the act complained of with a view, under the influence of insane delusion, of redressing or revenging some supposed grievance or injury, or of producing some supposed public benefit?"
In answer to which question, assuming that your Lordships' inquiries are confined to those persons who, labour under such partial delusions only, and are not in other respects insane, we are of opinion that, notwithstanding the party accused did the act complained of with a view, under the influence of insane delusion, of redressing or revenging some supposed grievance or injury, or of producing some public benefit, he is nevertheless punishable according to the nature of the crime committed, if he knew at the time of committing such crime that he was acting contrary to law; by which expression we understand your Lordships to mean the law of the land.
Your Lordships are pleased to inquire of us, secondly, " What are the proper questions to be submitted to the jury, where' a person alleged to be afflicted with insane delusion respecting one or more particular subjects or persons, is charged with the commission of a crime (murder, for example), and insanity is set up as a defence? " And, thirdly, "In what terms ought the question to be left to the jury as to the prisoner's state of mind at the time when  the act was committed " And as these two questions appear to us to be more conveniently answered together, we have to submit our opinion to be, that the jurors ought to be told in all cases that every man is to be presumed to be sane, and to possess a sufficient degree of reason to be responsible for his crimes, until the contrary be proved to their satisfaction; and that to establish a defence on the ground of insanity, it must be clearly proved that, at the time of the committing of the act, the party accused was labouring under such a defect of reason, from disease of the mind, as not to know the nature and quality of the act he was doing; or, if he did know it, that he did not know he was doing what was wrong. The mode of putting the latter part of the question to the jury on these occasions has generally been, whether the accused at the time of doing the act knew the difference between, right and wrong: which mode, though rarely; if ever, leading to any mistake with the jury, is not, as we conceive, so accurate when put. generally and in the abstract, as when put with reference to the party's knowledge of right and wrong in respect to the very act with which he is charged. If the question were to be put as to the knowledge of the accused solely and exclusively with reference to the law of the land, it might tend to confound the jury, by inducing them to believe that an actual knowledge of the law of the land was essential in order to lead to a conviction; whereas the law is administered upon the principle that every one must be taken conclusively to know it, without proof that he does know it. If the accused was conscious that the act was one which he ought not to do, and if that act was at the same time contrary to the law of the land, he is punishable; and the usual course therefore has been to leave the question to the jury, whether the party accused had a sufficient degree of reason to know that he was doing an act that was wrong: and this course we think is correct, accompanied with such observations and explanations as the circumstances of each particular case may require.
The Court (Dixon CJ, Webb and Kitto JJ)
1. The applicant Terence Charles Stapleton was convicted of murder before the under s. 21 of the Supreme Court Ordinance 1911-1936 (N.T.) to this Court for leave to appeal against the conviction. We granted leave to appeal and ordered that the application be treated as an appeal which appeal should be heard instanter. We then set aside the verdict and sentence and ordered a new trial. We did not then give our reasons because we thought it better to reduce them to writing. We now proceed to state the reasons why we considered that the verdict ought not to stand and there should be a new trial. (at p360)
2. The charge was that the appellant did murder one William Bryan Condon, a constable of police, at Katherine on 9th June 1952. The defence made for the appellant was that he was insane at the time of the commission of the offence.
17. The one exception in which the direction appears to us to be erroneous in what was positively said is in stating the question on the second branch of the legal test of insanity to be whether the accused knew that firing a shot at another person was against the law. This direction is in conformity with the decision of the Court of Criminal Appeal in R. v. Windle (1952) 2 QB 826 but that decision is one that we are not prepared to accept or act upon. In the course of the century that has passed since the judges formulated the legal test of insanity for the information of the House of Lords in consequence of the acquittal of Daniel M'Naghten (1843) 10 Cl & Fin 200 (8 ER 718); 1 Car & K 130 (174 ER 744) , there have been instances in which the same interpretation has been given to the words used by the judges in their third answer viz.: "that he did not know that he was doing wrong"
29. While as we have said it is not probable that because of this direction alone we would have ordered a new trial, it is desirable to say that if a jury were to lay hold of this point that the accused must be incapable of understanding that he was acting contrary to law as distinguished from appreciating that his act was wrong according to the ordinary standards adopted by reasonable men, the distinction would tell against the appellant.
Barwick CJ (would refuse special leave)
1. Robert Patrick Ryan was convicted on 15th September 1964 by a jury at the Central Criminal Court, Sydney, of the murder of Noel Francis Taylor at Carramar, a suburb of Sydney, on 10th March of that year. He was sentenced to life imprisonment according to the statute (Crimes Act 1900-1961 (N.S.W.)). (at p207)
30. In my opinion, therefore, leaving for separate treatment the question of "felony murder", the situation in this case at the close of the evidence, apart from the limiting effect of the applicant's line of defence, was that the jury could decide that the act causing death was the discharge of the gun and that it was discharged voluntarily by the applicant with intent to kill the deceased or to inflict grievous bodily harm upon him, or that it was done during the commission of an act obviously dangerous to human life. Those findings would warrant a verdict of guilty of murder. Or the jury might decide that the act causing death was the discharge of the gun but that it was not the voluntary act of the accused, in which event, in my opinion, quite apart from and not to any extent dependent upon any of the provisions of s. 18 (2) of the Crimes Act but solely because on that view the act causing death was not the act of the applicant, the verdict should be one of acquittal. (at p219)
Taylor and Owen JJ (would refuse special leave)
Menzies J (would refuse special leave)
7. Turning now to the direction actually given, I find it did substantially cover what I regard as necessary as a matter at law. It is true that there are passages in the charge which fail to identify what is described as an act done "with reckless indifference to human life" with the act of the accused "causing the death charged", and other passages which fail to link up "an act obviously dangerous to life" and the act of the accused "causing the death charged". In other ways, too, the use which the jury might make of the evidence that the shooting was accidental could, with advantage to the jury, have been indicated with greater particularity. These and some other like matters were the subject of criticism by counsel for the applicant but they are not in themselves matters which seem to me to warrant special leave to appeal. The main questions are whether the charge did clearly bring home to the jury (1) the matters which had to be found against the accused before he could be convicted of murder; and (2) the substance of the case for the defence that the killing was merely accidental. I think it did. Furthermore, the direction did not give the jury any false basis in law for finding the verdict which was returned. Had it done so, as, for instance, by a mis-statement of the effect of s. 98 of the Crimes Act to the disadvantage of the accused, I do not think the conviction could be allowed to stand, notwithstanding that there may have been other grounds which could justify it. (at p236)
Windeyer J (would refuse special leave)
Mason CJ, Brennan and McHugh JJ (would grant the Crown Special Leave but dismiss the appeal)
1. Mary Sandra Falconer was convicted before the Supreme Court of Western Australia of the wilful murder of her husband Gordon Robert Falconer on 9 October 1988. The deceased was killed when Mrs Falconer fired a shotgun, the blast of which struck the deceased at close quarters. She gave evidence at her trial of the difficulties she had had with her husband during their marriage. They had separated as the result of Mrs Falconer having discovered from her adult married daughters that, in their earlier years, their father had dealt with them sexually. Just before the shooting, he taunted her in a way which suggested to her that he had had some sexual dealings with a young girl who had been in her custody. Yet, it appeared, she had continued to love him…
(e) on the day of the shooting, according to the appellant, her husband had
(i) entered the appellant's house unexpectedly;
(ii) sexually assaulted the appellant;
(iii) demonstrated dramatic changes of mood;
(iv) taunted her with the suggestion that neither the daughters nor the appellant would be believed in court; and
(v) reached out at her apparently to grab her by the hair.
From that point the appellant said she remembered nothing until she found herself on the floor with her shotgun by her and her husband dead on the floor nearby."
4. The learned Commissioner rejected the evidence, but the Court of Criminal Appeal held that the evidence was admissible on the issue of "voluntariness", that is, on the issue whether the act causing Mr Falconer's death was a willed act. The Court allowed Mrs Falconer's appeal against conviction and ordered a retrial. The Crown seeks special leave to appeal against that order, submitting that the questions of law raised by the learned Commissioner's ruling and the judgments in the Court of Criminal Appeal are of far-reaching importance in the administration of the criminal law. We agree. From the time when Sir Owen Dixon delivered his paper "A Legacy of Hadfield, M'Naghten and Maclean", (1957) 31 Australian Law Journal 255, the relationship between involuntariness and insanity has awaited consideration by this Court. In the meantime, the problem has received extensive consideration in other courts and in learned writings.
7. In the present case, what is the "act" to which the first limb in s.23 refers? Is it merely a muscular movement of the accused's body (the contraction of the trigger finger), or is it the discharging of the loaded gun, or is it the entirety which commences with the contraction of the trigger finger and ends with the fatal wounding of the deceased? In one sense, it can be said that the discharge of a gun is the consequence of a bodily movement of contracting the trigger finger. In our opinion, however, a consequence which the bodily movement is apt to effect and is inevitable and which occurs contemporaneously with the bodily movement is more appropriately regarded as a circumstance that identifies the character of the "act" which is done by making the bodily movement: cf. per Barwick C.J. in Timbu Kolian, at p 53. Adopting the meaning of "act" expressed by Kitto J. in Vallance, the act with which we are concerned in this case is the discharge by Mrs Falconer of the loaded gun; it is neither restricted to the mere contraction of the trigger finger nor does it extend to the fatal wounding of Mr Falconer.
8. Mrs Falconer is criminally responsible for discharging the gun only if that act were "willed", that is, if she discharged the gun "of (her) own free will and by decision" (per Kitto J. in Vallance, at p 64) or by "the making of a choice to do" so (per Barwick C.J. in Timbu Kolian, at p 53). The notion of "will" imports a consciousness in the actor of the nature of the act and a choice to do an act of that nature. In Mamote-Kulang (at p 81) and Timbu Kolian (at p 64) Windeyer J. added "some element of intention" to the notion of will but, with great respect, such an addition might cause confusion between will and intent in the Code in much the same way as voluntariness is liable to be confused with general intent in the context of the common law: see He Kaw Teh v. The Queen  HCA 43; (1985) 157 CLR 523, at pp 569-572. Barwick C.J. was alive to the distinction between will and intent in Ryan. He noted that intent usually relates to consequences, whereas will relates to the act done (the deed, as his Honour calls it) the doing of which is ordinarily presumed to have been willed. In Ryan, immediately following the passages earlier cited from his Honour's judgment, he said (at p 213)…
9. In the absence of some contrary evidence, it is presumed - sub silentio, as Barwick C.J. said - that an act done by a person who is apparently conscious is willed or done voluntarily. That presumption accords with, and gives expression to, common experience. Because we assume that a person who is apparently conscious has the capacity to control his actions, we draw an inference that the act is done by choice. Keeping steadily in mind that the concepts of will and voluntariness relate merely to what is done, not to the consequences of what is done, it would be an exceptional case in which a person, apparently conscious, committed an act proscribed as an element in a criminal offence without choosing to do so - or, at the least, without running the risk of doing so. (We need not now consider criminal responsibility for the running of a risk of engaging in proscribed conduct.) The presumption that the acts of a person, apparently conscious, are willed or voluntary is an inference of fact and, as a matter of fact, there must be good grounds for refusing to draw the inference. Generally speaking, grounds for refusing to draw the inference appear only when there are grounds for believing that the actor is unable to control his actions. Although the prosecution bears the ultimate onus of proving beyond reasonable doubt that an act which is an element of an offence charged was a willed act or, at common law, was done voluntarily (Woolmington v. The Director of Public Prosecutions  UKHL 1; (1935) AC 462; R. v. Mullen  HCA 12; (1938) 59 CLR 124), the prosecution may rely on the inference that an act done by an apparently conscious actor is willed or voluntary to discharge that onus unless there are grounds for believing that the accused was unable to control that act.
16. The references to "disease of the mind" in these speeches come, of course, from the definition of insanity in the Rules in M'Naghten's Case (1843) 10 Cl & F 200, at p 210 (8 ER 718, at p 722); 4 St Tr (N.S.) 847, at p 931:
"the jurors ought to be told in all cases that every man is to be presumed to be sane, and to possess a sufficient degree of reason to be responsible for his crimes, until the contrary be proved to their satisfaction; and that to establish a defence on the ground of insanity, it must be clearly proved that, at the time of the committing of the act, the party accused was labouring under such a defect of reason, from disease of the mind, as not to know the nature and quality of the act he was doing; or, if he did know it, that he did not know he was doing what was wrong."
28. In a given case, if the psychological trauma causes a sound mind, possessed of the requisite standard of strength, to malfunction only transiently so as to produce the effects mentioned in the M'Naghten Rules or in s.27 of the Code, the malfunction cannot be attributed to mental infirmity but to "the nature of man": that is to say, a malfunction which is transient and not prone to recur and to which the mind of an ordinary person would be subject if exposed to the same psychological trauma is neither a mental disease nor a natural mental infirmity. It is neither an instance of unsoundness of mind under the Code nor an instance of insanity at common law. Having regard to the reason for distinguishing between sane and insane mental irresponsibility in Hill v. Baxter, there is no reason to require such a malfunction of the mind to attract a qualified verdict of acquittal.
29. If this be the substantive law, how does the shifting onus of proof work upon it? When an accused raises automatism and assigns some malfunction of the mind as its cause, he raises a defence of unsoundness of mind or insanity unless the malfunction of his mind was (1) transient (2) caused by trauma, whether physical or psychological, which the mind of an ordinary person would be likely not to have withstood and (3) not prone to recur. A malfunction of the mind other than a malfunction which satisfies those exempting qualifications amounts to a disease of the mind, or a mental disease or natural mental infirmity. As an accused bears no ultimate onus of proving that his act was not willed, in theory an accused may raise the issue of non-insane automatism on the evidence and claim to be acquitted outright unless the prosecution disproves the issue. But in practice an accused does not raise non-insane automatism by raising automatism based merely on mental malfunction. Prima facie, mental malfunction is the consequence of mental infirmity and, until it be proved that a particular instance of mental malfunction satisfies the exempting qualifications, mental malfunction must be treated as a consequence of mental infirmity.
30. It follows that, unless and until the automatism on which an accused relies is proved to be merely a transient mental malfunction of his otherwise sound mind caused by trauma and that the malfunction is not likely to recur, both s.26 of the Code and the common law preclude consideration of automatism for the purpose of determining whether the incriminated act was willed or voluntary. If an accused proves on the balance of probabilities that he was acting as an automaton when the act was done by reason of mental malfunction but fails to prove that his mental malfunction satisfied the exempting qualifications, he is entitled to be acquitted on account of unsoundness of mind or on the ground of insanity. However, if he proves that his mental malfunction satisfied the exempting qualifications, he is entitled to an outright acquittal. (To cast this onus on the accused does no violence to the principle in Woolmington v. The Director of Public Prosecutions, for the issue is not one of criminal responsibility but the cause of the condition which deprived the accused of criminal responsibility.) In some instances (for example, concussion caused by physical trauma), the accused may be able to prove on the balance of probabilities at the outset that, if there were any malfunction of the mind which deprived him of the capacity to know the nature and quality of his act or to control his actions, the malfunction satisfied the exempting qualifications and therefore did not flow from an underlying mental infirmity. In such a case, the onus shifts to the prosecution to prove beyond reasonable doubt that there was no malfunction or that it did not affect the accused's control of his actions. But in cases where the accused, claiming to have acted as an automaton by reason of a transient malfunction precipitated by psychological trauma, seeks to take the malfunction out of the prima facie classification of unsoundness of mind or insanity, the onus of proving the exempting qualifications can hardly be discharged before the malfunction itself is proved. Where the accused succeeds in proving that the relevant act was done in a state of automatism by reason of a malfunction of his mind, he is at risk of a qualified verdict of acquittal (under s.653 or a provision corresponding with that section) unless and until he succeeds in discharging the onus of proving the exempting qualifications on the balance of probabilities.
36. Had Mrs Falconer, having raised the issue of automatism caused by a mental malfunction, discharged the onus of proving that the malfunction satisfied the exempting qualification, she would have been entitled to be acquitted under s.23. Accordingly, the evidence was admissible as relevant to an issue arising under s.23 and the Court of Criminal Appeal was correct in allowing the appeal and ordering a new trial. However if, on the retrial, Mrs Falconer were to prove no more than the dissociated state occasioning an incapacity to control her action in discharging the gun, she would be entitled merely to a qualified verdict of acquittal under s.653. If the accused were not to prove any of the facts referred to in this paragraph, she would not be entitled to be acquitted under either s.23 or s.653.
37. We would grant special leave to appeal but dismiss the appeal.
Deane and Dawson JJ (would grant the Crown Special Leave but dismiss the appeal)
1. Subject to what is said below, we are in general agreement with the reasoning of Toohey J. and Gaudron J. That reasoning accords with the approach adopted by the members of the Western Australian Court of Criminal Appeal (Malcolm C.J., Wallace and Kennedy JJ.) and is in conformity with the basic principle of the criminal law in all parts of this country that, subject only to well-settled (common law) or clearly expressed (Code) exceptions, the onus lies upon the prosecution to prove the elements of an alleged criminal offence in accordance with the ordinary criminal standard of proof. It is also supported by what seem to us to be the more convincing discussions of relevant principle in the reported cases: see, for example, Rabey v. The Queen (1980) 2 SCR 513, at pp 545-552; (1980) 54 CCC (2d) 1, at pp 26-31 (per Dickson J., dissenting); Reg. v. Carter  VicRp 19; (1959) VR 105, at pp 110-111 (per Sholl J.); and Reg. v. Radford (1985) 42 SASR 266, at pp 272-276 (per King C.J.). In what follows, we express in somewhat summary form our views in relation to the various questions involved in the case, including the interaction of issues of sane automatism and insanity if both arise for the consideration of the jury in a particular case. References to "the Code" are to the Western Australian Criminal Code.
10. The problem is complicated by the consideration that it is no longer entirely appropriate to speak of insanity as a defence, having regard to the fact that the consequences of successfully raising the plea go beyond negativing volition or intent. True it is that insanity operates to produce an acquittal, but it is seldom raised by an accused now that there are no capital offences, because incarceration at the Governor's pleasure may be a harsher penalty than conviction and sentence. Indeed, nowadays it is often in the interests of the prosecution (or, at all events, the community) to raise the question of insanity, rather than in the interests of the accused. It used to be said that it was for the defence to raise a plea of insanity and not for the prosecution. That is probably still the case, but we think that the position has now been reached where it is only realistic to recognize that, if there is evidence of insanity, the prosecution is entitled to rely upon it even if it is resisted by the defence. In that regard, it is relevant to note that s.653 of the Code refers to the case where "it is alleged or appears" (emphasis added) that the accused was not of sound mind. It may be anomalous for the prosecution to raise the matter initially because the prosecution should not commence proceedings if it is seeking an acquittal, even on the grounds of insanity. The responsibility for the protection of the community in those circumstances lies elsewhere than in the criminal law. But we can see no reason why, if there is evidence which would support a verdict on the grounds of insanity, the prosecution should not be able to rely upon it in asking for a qualified acquittal as an alternative to conviction.
12. It follows that, in a case where an issue of sane automatism is raised by positive evidence (including expert medical opinion), an accused will be entitled to an acquittal if the prosecution fails to disprove sane automatism beyond reasonable doubt. In that event, the jury will need to go no further. If, however, the prosecution disproves sane automatism and the evidence raises the question of insane automatism, the jury will have to ask themselves whether, on the balance of probabilities, the evidence establishes insanity under s.27. That will, as we have said, embrace insane automatism. If the evidence does establish insanity, an accused will be entitled to an acquittal, but the jury will be required to say that the acquittal is on account of unsoundness of mind. If the prosecution does disprove sane automatism and if insanity is not established on the balance of probabilities, in the absence of any other defence the jury should convict.
Toohey J (would grant the Crown Special Leave but dismiss the appeal)
1. By this application the Crown seeks special leave to appeal from a judgment of the Court of Criminal Appeal of Western Australia which quashed Mrs Falconer's conviction on a charge of wilful murder of her husband and ordered a new trial on that charge. The Crown seeks restoration of the conviction and of the sentence of life imprisonment that accompanied it.
2. The circumstances giving rise to Mrs Falconer's appeal to the Court of Criminal Appeal arose from a voir dire conducted by the Commissioner who presided at her trial. The voir dire was conducted after the Crown had concluded its case and after the defence had called evidence from several witnesses, including the accused. It was designed to test the admissibility of evidence to be adduced by the defence from two psychiatrists, Johan Andreas Schioldann-Nielsen and Robert Astley Finlay-Jones. In his ruling that the evidence was inadmissible, the Commissioner spoke of "medical evidence which the defence would propose to call to support a defence of automatism or involuntary conduct within the meaning of the first limb of section 23 of the Criminal Code". In his judgment in the Court of Criminal Appeal, Malcolm C.J. described the evidence as relating to "the issues of non-insane automatism or disassociated state and accident". The question of accident is no longer an issue.
29. But there are real difficulties with the "external factor" test. Sleepwalking and the diabetic condition of hypoglycaemia stem from internal malfunctioning and yet have traditionally been treated as instances of automatism. How then does one apply the test in the case of dissociation or "psychological blow" automatism? The result of the decisions in Quick, Sullivan, Hennessy and Rabey is that a successful defence based on automatism arising from a dissociative state will ordinarily lead to a verdict of unsoundness of mind. But, as Glanville Williams points out at pp 674-675, Lawton L.J., in Quick, was concerned to place a limitation upon Lord Denning's test in Bratty, by drawing attention to those who were not held to be suffering from a mental disease. To borrow Professor Williams' comment, at p 675…
31. In my view, the approach taken by King C.J. is the approach dictated by the relevant provisions of the Code. At the risk of repetition, a person is not criminally responsible for an act or omission which occurs independently of the will. Dissociation may warrant a conclusion that the act or omission in respect of which an accused is charged occurred independently of his or her will.
32. The question raised by this appeal is whether the act of shooting occurred independently of Mrs Falconer's will. If the act of shooting occurred independently of Mrs Falconer's will by reason of involuntary conduct not arising from insanity, she is entitled to an unqualified acquittal. There is nothing more for the jury to determine. If the evidence requires a jury to consider both non-insane automatism and insanity, the question of involuntary conduct should be put in two stages. That is because each of those states of mind is governed by a different section of the Code and the onus of proving each state of mind falls differently. The jury should first ask itself whether the Crown has disproved, beyond reasonable doubt, non-insane automatism (the onus of proof in relation to that defence being on the Crown). If the Crown has failed to do so, then the accused will be entitled to an unqualified acquittal.
33. But if the Crown has disproved non-insane automatism, it may have done so, not because the acts said to constitute the offence were voluntary, but because they were the involuntary product of an unsound mind. Thus, if the answer to the first question is in the affirmative, the jury should go on to ask a second question, namely, whether the accused has proved, on the balance of probabilities, insanity within the meaning of s.27 (the onus of proof in relation to that defence being on the accused since s.26 presumes every person to be of sound mind). If the answer to that second question is in the affirmative, the jury should acquit but with the rider that the accused was of unsound mind at the relevant time. More precisely, the jury must consider whether the acts constituting the offence were done at a time when the accused was in such a state of mental disease as to produce one of the consequences referred to in s.27. There is of course a logical difficulty, in those circumstances, in inviting the jury to consider whether the accused was unable, by reason of mental disease, to control his or her actions. However, if "it is alleged or appears that he was not of sound mind at the time when the act or omission alleged to constitute the offence occurred" (the language of s.653), the appropriate verdict is acquittal on account of unsoundness of mind…
Gaudron J (would grant the Crown Special Leave but dismiss the appeal)
4. Like the formulation of the common law defence of insanity in M'Naghten's Case (1843) 10 Cl & F 200 (8 ER 718), the Code provisions dealing with insanity or unsoundness of mind direct a two-staged enquiry. The first question is whether the accused had a mental disease or a natural mental infirmity (s.27) or a mind disordered in one or other of the ways specified in s.28. If none of these conditions was present, no question of insanity arises. If one or other of the conditions was present, the accused is entitled to escape criminal responsibility if, but only if, the condition was such as to have one or other of the consequences specified in s.27. See, for example, R. v. Porter  HCA 1; (1933) 55 CLR 182; Willgoss v. The Queen  HCA 5; (1960) 105 CLR 295; R. v. Moore (1908) 10 WALR 64; Hitchens v. The Queen (No.2) (1962) Tas SR 35, at p 49. And, like the common law defence of insanity, it is for the accused to establish, on the balance of probabilities, the matters which constitute the defence. See s.26 of the Code. See also Sodeman v. The King  HCA 75; (1936) 55 CLR 192; Armanasco v. The King (1951) 52 WALR 78; Reg. v. Foy (1960) Qd R 225.
13. The evidence led in the present case raised no issue of insanity, but it did raise the question whether Mrs Falconer's act of discharging the loaded shotgun was done independently of her will. It should have been admitted as relevant to that issue and the jury should have been directed to consider whether, in the light of that evidence, the prosecution had proved beyond reasonable doubt that Mrs Falconer's will accompanied the act of discharging the gun. It should have been explained to the jury that the prosecution would not have proved that issue beyond reasonable doubt if it was a reasonable hypothesis that Mrs Falconer discharged the gun while experiencing that particular mental state described in the evidence as one that may be experienced by a normal or healthy mind and in which the personality is segmented so that acts are performed independently of the will. And it might conveniently have been explained that that hypothesis would be excluded by satisfaction beyond reasonable doubt either that there is no such phenomenon as the particular mental state described in the evidence or that Mrs Falconer did not experience it.
14. There must be a new trial. Although the evidence by reference to which the present application was argued does not raise any issue of insanity it does not follow that insanity will not be raised in the new trial. It may be that the prosecution will assert that, if, at the time of discharging the loaded shotgun, Mrs Falconer experienced any mental state other than one in which she had acted consciously and deliberately, it was a state (perhaps similar in effect to that as to which evidence was led at the first trial) involving a mental disease or natural mental infirmity. Or, perhaps, the defence will postulate, as an alternative to the mental state of dissociation, some other state which involves a mental disease or natural mental infirmity.
The Court (Mason CJ, Brennan, Deane, Dawson and Gaudron JJ)
1. On the morning of 27 October 1990, the appellant, then aged 16, and his father went into a pine plantation at Railton. The appellant had a gun. He fired it in the direction of his father and the bullet entered the father's heart and killed him. The appellant was charged with murder under s.158 of the Tasmanian Criminal Code ((1) Schedule 1 to the Criminal Code Act 1924 (Tas.).) ("the Code"). Murder is defined by s.157(1) which provides, inter alia, as follows…
" Subject to the provisions of section 160, culpable homicide is murder if it is committed -
(a) with an intention to cause the death of any person, whether of the person killed or not;
(b) with an intention to cause to any person, whether the person killed or not, bodily harm which the offender knew to be likely to cause death in the circumstances, although he had no wish to cause death”.
The prosecution case was one of premeditated murder. The defence case was that the appellant entered the pine plantation intending to commit suicide in his father's presence and that at the last moment, in a disturbed state of mind, he turned the rifle from himself towards his father and pulled the trigger without having the specific intention necessary to establish the crime of murder.
2. The appellant has been tried three times. On his first trial, he raised the defence of insanity but the jury was unable to reach a verdict. In the course of the second trial, he withdrew the defence of insanity, the jury convicted him but the Court of Criminal Appeal allowed an appeal and ordered the third trial. On the third trial before Underwood J, the prosecution adduced evidence of several accounts which the appellant had given of the killing of his father. Among those accounts was the appellant's unsworn statement at the second trial which contained this description of the critical events:
"I held the gun out on the right hand side up to my head, thumb on the trigger, right hand. I wanted him to see me shot myself. I was standing just down from the top of the drain. I heard Dad coming. I just saw him - he came out from around a bush he was about seven to eight metres away. I don't know whether he saw me. Then everything flashed through my head.
Him bashing Mum, Mum being bashed by my step-father, flashes through me mind were pictures of Nan's coffin, arguments between Mum and Dad, what he'd done to me, all muddled thoughts - then why not him instead of me – he caused most of it. The thoughts went through my head not in any order but all muddled and at the same time. I put the gun from my head down to my hip and pulled the trigger within a second. It went off, Dad fell down, I didn't see where the bullet hit, he fell on his face. I just pointed the gun at him and pulled the trigger, I didn't aim it. He didn't say anything before or after the gun went off. It all happened at once - very quickly all in the one moment. At the time I pulled the trigger I can't recall any thoughts that were happening. I wasn't thinking about what I was doing or the consequences."
After the prosecution case was closed, his Honour held a voir dire in order to determine the relevance and admissibility of the evidence of Dr Sale and Professor Jones whom the defence wished to call in order to raise a reasonable doubt as to the appellant's intent when the gun was fired. Counsel for the appellant neither raised a defence of insanity nor wished that defence to be put to the jury. Underwood J ruled that the medical evidence was inadmissible for any purpose other than insanity. The trial proceeded without the evidence of Dr Sale and Professor Jones. The jury convicted the appellant of murder. The Court of Criminal Appeal by majority (Cox and Crawford JJ, Zeeman J dissenting) dismissed his appeal. The appeal to this Court turns on the admissibility of the medical evidence on the issue of the existence of the specific intent necessary to proof of murder.
9. It follows that, if the only evidence tendered to raise the question of the voluntariness of the incriminated act is evidence of a mental abnormality amounting to a "mental disease" under s.16 ((10) or "mental disease or natural mental infirmity" under the Codes of Western Australia and Queensland.), the admissibility of the evidence does not depend on its relevance to the issue of voluntariness but on its relevance to the issue of insanity. And, if there be evidence of mental disease but the evidence is incapable of proving that the mental disease produced any of the consequences prescribed by pars (a) and (b) of s.16(1), that evidence is both insufficient to establish insanity and irrelevant to the issue of voluntariness.
19. It follows that, if there be evidence that the accused was suffering from a mental disease when the incriminated act was done and the evidence is capable of supporting a finding of insanity, the trial judge must give the jury a direction on that issue. Evidence of mental disease that is incapable of supporting a finding of insanity or that does not satisfy the jury that the accused was insane when the incriminated act was done, is inadmissible on, and must be taken to be irrelevant to, the issue whether the act was "voluntary and intentional" within the meaning of those terms in s.13 of the Code. But such evidence of mental disease is relevant to and admissible on the issue of the formation of a specific intent - relevantly, the intents prescribed by pars (a) and (b) of s.157(1) of the Code. The Courts below were in error in holding that the evidence of Dr Sale and Professor Jones was inadmissible on the issues of those intents.
1. It is a fundamental principle of the criminal law that a person is not guilty of a crime if the act which would constitute it was not done in exercise of the accused’s will to perform it.For, as it was put by Lord Denning in Bratty v Attorney-General for Northern Ireland:
No act is punishable if it is done involuntarily: and an involuntary act in this context — some people nowadays prefer to speak of it as “automatism” — means an act which is done by the muscles without any control by the mind, such as a spasm, a reflex action or a convulsion; or an act done by a person who is not conscious of what he is doing, such as an act done whilst suffering from concussion or whilst sleep-walking. The point was well put by Stephen J. in 1889: “Can anyone doubt that a man who, though he might be perfectly sane, committed what would otherwise be a crime in a state of somnambulism, would be entitled to be acquitted? and why is this? Simply because he would not know what he was doing,” see Reg. v. Tolson [(1889) 23 QBD 168, at p 187]
2. In this Crown appeal, the immediate issue is whether the respondent, who was acquitted at a judge-alone trial in the District Court of two counts of sexual touching of his daughter because he was asleep and therefore acting involuntarily, ought instead have been the subject of a special verdict of “act proven but not criminally responsible” under s 30 of the Mental Health and Cognitive Impairment Forensic Provisions Act 2020 (NSW) (“2020 Act”). However, the larger question which arises is whether the effect of the 2020 Act is effectively to abolish the “defence” of “sane automatism”, by providing that a person who lacks volition by reason of being asleep at the time of the charged act has a mental health impairment
3. The respondent was tried on an indictment which charged him with three offences, to the following effect:
that on 30 June 2019, at Camden in the State of New South Wales, he had sexual intercourse with the complainant, a child then under the age of 10 years, namely 9 years, contrary to s 66A(1) of the Crimes Act;
that on or about 2 November 2019, at Wollongong in the State of New South Wales, he had sexual intercourse with the complainant, a child then under the age of 10 years, namely 9 years, contrary to s 66A(1) of the Crimes Act; and
that on or about 2 November 2019, at Wollongong in the State of New South Wales, he intentionally sexually touched the complainant, a child then under the age of 10 years, namely 9 years, contrary to s 66DA(a) of the Crimes Act
4. At the trial it was not in issue that the respondent had, on two occasions, sexually touched the complainant, his young daughter. There was an issue, which was resolved in favour of the respondent, as to whether the touching involved penetration so as to amount to sexual intercourse; accordingly, the statutory alternative to the offence the subject of each of counts 1 and 2, being sexual touching contrary to s 66DA(a) of the Crimes Act, fell to be considered. The respondent’s defence was that his conduct was involuntary: he was asleep, and this was a manifestation of sexsomnia, a parasomnia or form of somnambulism (sleepwalking) in which a person engages in sexual activity while asleep. The Crown accepted that when he performed the charged acts, the respondent was asleep and that his acts were not voluntary. It is unsurprising that this was uncontentious, given that it was the complainant’s evidence that the respondent was snoring at the time of at least one if not both of the episodes. The chief issue at the trial was whether the accused was entitled to an outright acquittal by reason that his acts were involuntary, or whether he had a mental health impairment within s 4 of the 2020 Act with the consequence that there should be a special verdict of “act proven but not criminally responsible" pursuant to s 30 of that Act.
5. Conformably with the position conceded by the Crown, the trial judge found that the Crown had failed to prove to the requisite standard that any of the charged acts was voluntary. Turning to the issue of whether the respondent had a mental health impairment, his Honour concluded that he did not. The first reason for this conclusion was that, accepting expert psychiatric evidence that parasomnias are involuntary and not the product of a disordered mind, as those suffering from them typically have no psychopathology when awake, the respondent had an absence of volition rather than a disturbance of volition, and so did not fall within s 4(1)(a) of the 2020 Act. A second reason was that his Honour also concluded that any “disturbance” was not significant for clinical diagnostic purposes, as there appeared to be no consensus that parasomnias result in a true mental health diagnosis.
6. Further, his Honour concluded that even if the respondent had a mental health impairment within s 4, s 28 of the 2020 Act was not engaged in any event, as the respondent performed the acts unconsciously and involuntarily whilst he was asleep, without choice or decision, while s 28 was reserved for those who are conscious of their actions but either do not know the nature and quality of their acts or do not know that their acts were wrong.
7. Thus, having found that sexual intercourse had not been proved, verdicts of not guilty were returned on counts 1 and 2. On the basis of the finding that the acts of sexual touching were not voluntary, his Honour concluded:
“In my opinion, the Crown has failed to prove, on the balance of probabilities, that [the] accused, at the time of his actions in June and November 2019, suffered from a mental health impairment pursuant to section 4 of the MHCIFP Act. Further, in my opinion, the Crown has failed to prove, on the balance of probabilities, that any mental health impairment the accused may have suffered at those dates had the effect that he did not know the nature and quality of those acts or that he did not know that those acts were wrong within the meaning of section 28(1) of the MHCIFP Act. Thus that Act has no application in the circumstances, and I enter verdicts of not guilty to the statutory alternatives to counts 1 and 2 and count 3.”
33. From these cases it appears that unconscious acts attributable not to mental illness but to the transitory effects on a person of ordinary sound mind of conditions such as concussion, post traumatic epilepsy, hypoglycaemia, and somnambulism, characterise, although they do not necessarily define, “sane automatism”. In any event, for present purposes it is a notable feature of the cases to which reference has been made that “sleepwalking” is treated, effectively, as a paradigm case of sane automatism. There are numerous illustrations of its application.
43. It is, therefore, plain that in law the acts of a person who is asleep and engaging in somnambulistic activity are not willed acts; and the accused is not legally responsible for them. It makes no difference whether they would amount to murder, rape, or assault if the accused were awake and conscious. Given the incidence of sexual dreaming, one might think that sexsomnia might be less implausible than some of the cases described above. It is in my view therefore plain that, at common law, the respondent would have been entitled to the outright acquittal that he received from the trial judge. The question is whether the 2020 Act, which commenced on 27 March 2021, requires a different result.
54. As has been seen, the trial judge held that the respondent did not have a mental health impairment within s 4 for two reasons: first, that he did not have a “disturbance of … volition” within s 4(1)(a), and secondly, that any disturbance was not of clinical significance so as to fall within s 4(1)(b).
59. It is also a mistake to ask whether a parasomnia such as sexsomnia, unaccompanied by other psychopathology, constitutes a disturbance of volition. The labels parasomnia and sexsomnia, like somnambulism, describe the phenomena of a person performing, while asleep, various acts usually associated with willed behaviour of an awake person; they do not describe a person lacking while asleep the volition which every person lacks while asleep. The true issue is not whether sexsomnia is a mental health impairment, but whether the respondent had a disturbance of volition within s 4(1)(a). That issue is not assisted by argument over whether sexsomnia is a physiological or psychological disorder. Whatever accounts for the acts of the sleepwalker, it is not a lack of volition, but presumably the action of the subconscious mind.
60. Accordingly, in my opinion, the trial judge was right to hold that the applicant did not have a “disturbance of … volition” within s 4(1)(a); the only intrusion on his volition was that he was asleep, which is not a “disturbance” of volition at all. Although that suffices to dispose of the appeal, I shall address the remaining grounds.
61. The trial judge also held that s 4(1)(b) was also not engaged. In this respect, his Honour said:
“As to the requirement that the “disturbance” would be regarded as significant for clinical diagnostic purposes, I note the Attorney-General’s comments set out elsewhere in this judgment that the temporary or ongoing disturbance must be serious enough to result in a mental health diagnosis. Dr Ellis’s view was that to have significance, the disturbance needed to be accepted in the medical community as a diagnosis and that there was a need for standards around that diagnosis. In this case, the Crown relied on DSM-5 as establishing sexsomnia as a mental health diagnosis. DSM-5 is a manual that has been created to assist medical practitioners in treating patients. It includes disorders that could not possibly be classified as mental health impairments pursuant to section 4 of the MHCIFP Act. The examples of insomnia and of erectile dysfunction were noted on several occasions. In any event, I note Dr Fernando’s evidence that parasomnias were classified not only by DSM-5 but by the ICCB, and that persons other than psychiatrists treated persons with sleep disorders. Thus in my opinion, there appears to be no consensus that parasomnias result in a true mental health diagnosis or with respect to their treatment. I note the full content of the Cautionary Statement (exhibit 20). DSM-5 is not determinative of mental health impairment in the legal context.”
Section 28: application to involuntary acts
66. In those circumstances, Ground 3, which complains that the trial judge erred in finding, if at the time of carrying out the act constituting the offence the person had a mental health impairment within s 4(1), that unconscious and/or involuntary acts cannot fall within section 28 of the Act, does not strictly arise.
“In my opinion, it being the case that the accused performed the acts unconsciously and involuntarily whilst he was asleep – without choice or decision – means that he cannot fall within the ambit of section 28, which is reserved for those who are conscious of their actions but either do not know the nature and quality of their acts or do not know that their acts were wrong. So much has informed our law for almost 200 years. As was expressed by Mr Strickland, if Parliament meant to interfere with the long-recognised common law entitlement to acquittal in cases of involuntary acts (non-insane automatism), the principle of legality - a rule of statutory interpretation - would have required there to be clear and unambiguous words in the MHCIFP Act. No such words are found anywhere in the MHCIFP Act. I observe that the Act’s most significant change appears to be the inclusion of cognitive impairment.”
68. As it seems to me, involuntary acts resulting from a mental health impairment would be within s 28, just as insane automatism has historically attracted the application of the M’Naghten rules. I do not understand his Honour to have held to the contrary, given his Honour’s reference in the passage just quoted to “non-insane automatism”.
69. However if, contrary to my view, the respondent’s lack of volition were a mental health impairment, then it seems to me that s 28 would be engaged. Section 28 must be read with the definition of “mental health impairment” in s 4, and applies if at the time of carrying out the act alleged to constitute the offence, the person has a mental health impairment within s 4. Its application in such a case would not be affected by the circumstance that the accused performed the acts unconsciously and involuntarily.
70. To that extent, Ground 3 may have merit. However, given that the respondent has no mental health impairment, that could make no difference to the outcome in this case, and its ultimate resolution should be left to a case in which it matters.
71. Grounds 1 and 2 fail: the trial judge was right to hold that the respondent did not have a mental health impairment, because his lack of volition while asleep was not a disturbance of volition within s 4(1)(a), and was of no clinical significance for the purposes of s 4(1)(b). In those circumstances, the respondent was entitled to the outright acquittal he received. Ground 3 could not result in a different outcome. The appeal should be dismissed.
72. From 26 April to 30 April 2021 his Honour Judge Weinstein SC, sitting without a jury, heard evidence and submissions in the trial of the respondent before the District Court of New South Wales for child sexual assault offences. On 25 May 2021 the trial judge returned verdicts of not guilty to the offences charged on indictment and to all relevant statutory alternatives. The respondent was acquitted.
79. The trial was conducted expeditiously as the scope of the matters in dispute was limited. Other than the issue of penetration, relevant to proof beyond reasonable doubt of the element of sexual intercourse with respect to counts 1 and 2 of the indictment, the only real dispute between the parties was the issue of voluntariness as it applied in the context of a sleeping disorder from which the respondent suffered. There was no dispute that the respondent had sexually touched the complainant, his young daughter.
89. The respondent’s case was that he had acted involuntarily due to a parasomnia, sexsomnia, from which he suffered. His evidence went to the truth of the history given to the specialists who had assessed his condition, and to his good character.
146. This appeal centres on the proper construction and application of s 4 and s 28 of the MHCIFP Act, and the question of the relationship of those provisions to the common law. Some background as to the common law concerning mental illness, and non-insane and insane automatism is helpful.The Common Law and the MHCIFP Ac
147. The now repealed legislation, the Mental Health (Forensic Provisions) Act 1990 (NSW) (“MHFP Act”), which the MHCIFP Act comprehensively replaces, provided for the return of a special verdict of “not guilty by reason of mental illness” pursuant to s 38. The term “mental illness” used in the MHFP Act was understood by reference to the common law test or rules as given by the House of Lords in M’Naghten (1843) 10 Cl & Fin 200; 8 ER 718. That is:
“[…] to establish a defence on the ground of insanity, it must be clearly proved that at the time of committing the act, the party accused was labouring under such a defect of reason, from disease of the mind, as not to know the nature and quality of the act he was doing, or as not to know that what he was doing was wrong.”
174. It is clear from the evidence in this matter, including both that of the complainant and of the literature concerning sexsomnia, that a person acting without volition due to a parasomnia can commit acts which, if carried out deliberately, would constitute serious crime. A conclusion that an absence of a particular faculty, here volition, is not a mental health impairment and not caught by s 4 (and s 28) of the MHCIFP Act, prevents the achievement of the purposes of the Act. On that construction, there can be no regulation of the conduct and treatment of persons who commit a physical act that would ordinarily constitute a crime, and no means by which the safety of members of the public can be protected.
175. Viewing the provision in light of the purpose of the Part and of the Act supports a textual construction of it.
188. It is thus incorrect to view the purpose of s 4(1)(b) as preliminary only to the imposition of involuntary psychiatric institutionalisation and treatment.
189. The text of s 4(1), viewed within the context of the purpose of the Act, has wider application than does the common law concept of mental illness. The respondent argued before both the trial court and this Court that, in the absence of a clear statement of an intention to alter long-standing common law principle, it cannot be concluded that those principles have been abrogated. However, the Parliament did not, in introducing the legislation, simply codify the M’Naghten Rules, as was open to it. The statutory definition of mental health impairment is not the same as the common law concept of insanity or mental illness, and there is no basis to read the latter into the former.
193.The principle of legality cannot, in my opinion, be relied upon to read the MHCIFP Act as no more than the codification of the common law. The legislation is broader than that.
194. I am persuaded that there was error in the conclusions of the trial judge that led to him construing the meaning of s 4(1)(a) and (b) consistent with the common law concepts of a defect of reason caused by a disease of the mind, rather than in accordance with the plain meaning of the words, consistent with the purpose of the statute.
195. His Honour was not asked to, and did not, consider s 4(1)(c).
196. If a textual and purposive construction is applied to s 4(1), the evidence establishes that, on the two occasions when he sexually touched his 9-year-old daughter, the respondent had a temporary disturbance of volition (s 4(1)(a)); his condition was regarded as clinically significant in that it met the diagnostic criteria for the disorder of sexsomnia (s 4(1)(b)); and the disturbance impaired his behaviour (s 4(1)(c)).
197. I would uphold grounds 1 and 2.
Ground 3: That the trial judge in erred in finding, if at the time of carrying out the act constituting the offence the person had a mental health impairment pursuant to section 4(1) Mental Health and Cognitive Impairment Forensic Provisions Act 2020, that unconscious and/or involuntary acts cannot fall within section 28 of the Act
198. Although it was not strictly necessary to do so, given the construction he had placed upon s 4(1) of the Act, his Honour went on to consider whether the s 28 defence would have been established had he concluded that sexsomnia was a mental health impairment. He held that it would not, explaining, at  –  of the verdict judgment:
“In my opinion section 28 codifies the M’Naghten test. I note that the Attorney-General, in the Second Reading Speech, said: -
‘Clause 28 of the bill applies to matters in the District or Supreme courts. It provides for the defence of mental health impairment or cognitive impairment, which largely mirrors the test but with updated terms. The statutory test of the bill enables a person to show that they were not criminally responsible for an offence if, at the time of carrying out the act constituting the offence, the person had a mental health impairment or cognitive impairment, or both, that had the effect that the person “did not know the nature and quality of the act”, or “did not know that the act was wrong (that is, the person could not reason with a moderate degree of sense and composure about whether the act, as perceived by reasonable people, was wrong).”’
So much is clear from the language of section 28, which in fact picks up material parts of M’Naghten’s test and updates some language: see also Anina Johnson Forensic Provisions Act Amendments,  (Autumn) Bar News at 22 and Justice Mark Ierase [sic] Introducing the New Mental health and cognitive Impairment Forensic Provisions Act 2020 (2021) 33(2) JOB 15 at 17.
In my opinion, it being the case that the accused performed the acts unconsciously and involuntarily whilst he was asleep – without choice or decision – means that he cannot fall within the ambit of section 28, which is reserved for those who are conscious of their actions but either do not know the nature and quality of their acts or do not know that their acts were wrong. So much has informed our law for almost 200 years. As was expressed by Mr Strickland, if Parliament meant to interfere with the long-recognised common law entitlement to acquittal in cases of involuntary acts (non-insane automatism), the principle of legality - a rule of statutory interpretation - would have required there to be clear and unambiguous words in the MHCIFP Act. No such words are found anywhere in the MHCIFP Act. I observe that the Act’s most significant change appears to be the inclusion of cognitive impairment.”
199. In so saying, his Honour was in error in his understanding that the common law defence of insanity or mental illness had only ever applied to those who had conscious awareness of the nature and quality, and moral wrongness of their act. The common law defence of insane automatism stands for the contrary proposition: see Woodbridge v The Queen  NSWCCA 185; (2010) 208 A Crim R 503, and those cases quoted therein at  – .
200. His Honour was also in error, in my opinion, in giving greater weight to the principle of legality than to the text and purpose of s 4 and s 28 of the MHCIFP Act.
201. The two sections must be read together. Taking that approach, it follows from the conclusion that s 4(1) operates such that sexsomnia is a mental health impairment, that a person who commits a criminal act when impaired by the condition could not know the nature and quality of the act, or that it was wrong. In this instance, his impairment prevented the respondent from considering those questions and it must be concluded that he did not know at the time he did the acts their nature and quality, or that they were wrong.
202. I would uphold Ground 3.
204. I agree with Brereton JA