Drug-Use and the Defence of Insanity

Chapter 4
Drug-Use and the Defence of Insanity

Introduction

The question of whether someone who has suffered from drug-induced psychosis can use the defence of insanity is a pressing legal question which has arisen in several recent criminal trials in Victoria.¹ This chapter will critically examine several approaches which have been adopted in answer to this question before proposing a principled approach by way of conclusion.

The previous chapter highlighted three factors which it was suggested the criminal law endeavours to balance in determining which conditions will satisfy the legal expression ‘disease of the mind’. One of these is what was referred to as a judgment of responsibility. The judgment of responsibility allows us to determine the question of an agent’s moral and legal responsibility. The judgment of responsibility precludes punishing an accused individual whose mental condition renders him or her incapable of either knowingly choosing between right and wrong or controlling his or her conduct. The judgment of responsibility will be reflected in the scope of criminal-law defences dealing with individuals accused of engaging in criminal conduct. For example, the boundaries of the defence of insanity will seek to determine, according to principles of criminal responsibility, when an individual’s mental state will result in him or her being held non-responsible and as a result not liable to criminal sanctions. The present chapter will apply the judgment of responsibility to instances of drug-induced psychosis in order to clarify the proper scope of the defence of insanity. This will involve determining when the voluntary use of a drug leading to a state of psychosis will satisfy the judgment of responsibility factor informing the disease of the mind enquiry.

This chapter will analyse the various issues which arise as a result of attempts to raise a defence of non-responsibility for criminal conduct performed subsequent to voluntary drug use resulting in psychosis. As will be discussed in more detail in Chapter 5, the scope of the defence of insanity may be altered in one of two ways: either by restricting or expanding those states of mental malfunction which will be recognized as diseases of the mind or by restricting or expanding those conditions considered sufficiently incapacitating for the purposes of the defence. Instances of psychosis due to drug use involve the paradigmatic instance of cognitive incapacity, namely a psychotic state, and for this reason do not present any particular definitional issues in regards to the defect of reason aspect of the defence as traditionally understood.² Consequently, the present discussion will focus on whether states of psychosis arising from drug use should be recognized as instances of disease of the mind.

The present chapter draws on material previously presented in two articles on drug use and the defence of insanity either authored or co-authored by myself.³ The first, co-authored with Carroll, McSherry and Wood, acknowledged that there were a wide range of approaches to the issue of drug use and the defence of insanity in various legal jurisdictions. However, it was recognized as a structural point that three broad approaches to the problem were discernible: liberal, conservative and intermediate. This paper analysed legal, expert witness and policy perspectives relating to the three approaches developed by the three coauthors and myself, which will be discussed below. The paper was exploratory in scope and endeavoured to provide ‘an overview of possible approaches that the law may take [so as] at the very least move the debate forwards’.⁴ The single authored paper, while acknowledging the broad concerns of the group paper, aimed to ‘explore some of the underlying conceptual issues faced by legal theorists in responding to the voluntary consumption of psychoactive drugs’.⁵ This paper used the three broad approaches adopted in the group paper re-naming them ‘causal irrelevance’, ‘settled insanity’ and ‘meta-responsibility’, in keeping with each approach’s defining characteristic.

The present chapter adopts the structure of three broad approaches used in the two papers in order to develop the current substantive argument. However, the substantive argument of this chapter differs from that of the preceding papers in reflecting the central concerns of this book. Both of the earlier papers highlighted the various difficulties faced by all three approaches without endorsing one in particular. As a result, and in contrast to the earlier papers, this chapter will endeavour to present a principled response to the question of when drug-induced psychosis should be characterized as a disease of the mind. Moreover, by analysing the above approaches to the issue of an accused’s responsibility for states of drug-induced psychosis, it will be possible to develop the account of those factors informing the disease of the mind enquiry outlined in Chapter 3 above.

I begin with an outline of the nature of the problem presented by instances of psychosis arising from drug use and the approach to be adopted in this chapter.

The voluntary consumption of psychoactive drugs may result in what has been termed a drug-induced psychosis.⁶ The term ‘drug-induced psychosis’ will be used to describe a state of psychosis arising from the ingestion of psychoactive substances which is due to either the intoxicating effects of the substance, or the short-term symptoms associated with the use of such a substance subsequent to its physiological excretion or due to the chronic use of such a substance operating independently of either of the above.

In considering the issue of drug-induced psychosis a distinction may be drawn between two distinct types of question, one clinical, the other normative. In order to adequately frame the enquiry, I will begin by outlining the distinction between these two questions in respect of the use of drugs leading to psychosis. The first question asks whether the state of psychosis is due to the immediate effects of a drug or exists independently of the effects of the consumption of a drug. The first question arises as a result of the fact that states of psychosis arising from drug use have been classified according to whether they have been caused by one of two distinct types of reaction: an acute-onset psychotic state that resolves within a relatively short time-frame when an individual stops using the drug and a chronic psychotic state occurring with a history of prolonged usage.⁷ That is, a psychotic state may be due to the immediate intoxicating effects of a drug following its consumption or the relatively short-term symptoms associated with the use of a drug subsequent to its physiological excretion. Alternatively, a psychotic state may arise due to the chronic use of drugs and operate independently of either the intoxicating effects of a drug or the short-term symptoms associated with the use of a drug subsequent to its physiological excretion. Such a question is clearly a matter for expert evidence.

The second question asks whether the defence of insanity should be available to an accused who has voluntarily consumed drugs which have produced either an acute or chronic psychotic state. This latter question raises normative issues falling outside the exclusive purview of contemporary clinical research. In particular, the normative issues raised by this latter question concern the proper scope of the defence of insanity. This chapter is concerned with this second question which it will seek to answer by an analysis of the various problems posed by states of drug-induced psychoses. Three approaches in respect of establishing an accused’s responsibility for a state of drug-induced psychoses are discernible: Causal Irrelevance, Settled Insanity and Meta-Responsibility.

The first approach to the issue of when to characterize a drug-induced psychosis as a disease of the mind which I will consider was that proposed by the VLRC during its examination of homicide offences committed by people with mentally impaired functioning.⁸ Succinctly stated, the commission adopted the view that the causal antecedents of an accused’s behaviour should be irrelevant to the question of his or her responsibility. According to the commission, in keeping with the defence’s true purpose, if there is a cognitive failure on the part of an accused during the commission of the offence non-responsibility should follow as a matter of principle. That is, the VLRC claims that the source of a state of mental malfunction should make no difference to the non-responsibility of an accused. Where an accused experiences the relevant incapacities due to a state of mental malfunction, this will be sufficient to render him or her non-responsible. According to the VLRC the question of an accused’s non-responsibility will be determined by his or her incapacity not the cause of such incapacity. The relevant time-frame on this view is that concurrent with when the offending conduct is performed.

Settled Insanity

A second alternative approach to the issue of when to characterize a drug-induced psychosis as a disease of the mind is referred to as settled insanity. Settled insanity holds an accused non-responsible where a state of mental malfunction is diagnosable independently of drug use.⁹ Those theorists who argue for recognition of this approach hold that evidence of a state of settled insanity may be ascertained through evidence of a fixed, stable state of mental malfunctioning independent of an accused’s drug use. That is, the test of settled insanity is predicated on a finding of a state of mental malfunction both before and after the offending conduct has been performed. Such a state is indicative of the existence of a mental malfunction independent of the effects of an intoxicant operating at the time of the offence.

Meta-Responsibility

A third approach holds an accused responsible where he or she has, through his or her culpable behaviour, created the conditions of his or her own defence. Such an approach has been put forward by Edward Mitchell in the course of his discussion of the notion of meta-responsibility.¹⁰ Focusing on prior conduct, Mitchell argues that an accused is responsible where he or she has engaged in prior culpable behaviour that in turn creates the conditions of the defence relied upon. The relevant time-frame according to this view is that which occurs before the offending conduct is performed. Mitchell’s views will be examined below. In contrast to the VLRC view, meta-responsibility holds that the causal antecedents of an accused’s behaviour will be determinative of his or her responsibility. Where an accused’s prior culpable behaviour causes a state of mental malfunction which results in the relevant incapacities, then he or she should not be accorded a defence of insanity.

The proposed argument

In the concluding remarks to this chapter it will be argued that any attempt to clarify the proper scope of the insanity defence in the context of drug-induced psychoses must take into account the various factors informing the disease of the mind enquiry. Consequently, the approach endorsed by this chapter will use the insights of the previous chapter in respect of the factors which inform the disease of the mind enquiry.

It will be argued that of the three approaches above that which is most in accord with the insights of Chapter 3 is the approach referred to as meta-responsibility. However, it will also be shown that the doctrine of meta-responsibility is in need of further elaboration. In particular, the formulation of meta-responsibility put forward by Mitchell will be shown to fail to take into account the conditions under which responsibility is ascribed, diminished or lost. Hence, while advocating Mitchell’s general approach the final substantive section of this chapter will seek to extend the doctrine of meta-responsibility to account for these conditions.

The opening sections of the chapter will begin with an analysis of the three different approaches which have been adopted in respect of assigning criminal responsibility in cases of drug-induced psychosis. The latter sections of the chapter will analyse the nature of an individual’s responsibility for a state of drug-induced psychosis and finish by arguing for a preferred approach. However, before proceeding to detail the relative strengths and weaknesses of the three broad approaches above the next section will provide an overview of the current approach adopted by courts to the question of states of mental malfunction arising in the context of illicit drug use.

Intoxication and insanity

The consumption of intoxicants resulting in a temporary mental malfunction will not give rise to the defence of insanity as such a state of mental malfunction will not be recognized as a ‘disease of the mind’.¹¹ The leading case is R v Sebalj.¹² In Sebalj’s case the accused was found guilty of the murder of his girlfriend while in a state of paranoid psychosis resulting from his attempt to withdraw from the use of drugs. The accused was a user of various addictive drugs, such as amphetamines and cannabis, for several years prior to the killing of his girlfriend. During an attempt to extricate himself from his addiction to drugs the accused developed aural and visual hallucinations associated with psychosis. After he was referred to a hospital by police officers, his psychotic state was diagnosed. After treating the accused with medication to alleviate both his anxiety and psychosis, hospital staff released him in the care of his girlfriend. Arrangements were made by hospital staff for a nurse from the crisis assessment team to meet the accused later that evening. Upon arriving that evening the nurse was unable to gain access despite making repeated telephone calls to the accused. The accused finally emerged from the bungalow which he shared with the deceased with blood spattered on his clothes. It was held on the facts that he had stabbed his girlfriend in the belief that she was allowing someone who had come to kill him to enter.

At his trial there was ‘uncertainty as to how that element should be approached in the trial because of uncertainty as to the scope of the statutory defence of “mental impairment”’.¹³ After determining Parliament’s intent in passing the Act, Justice Smith noted that, ‘the term “a mental impairment” should not be construed as changing the common law but construed as referring to the concept of “a disease of the mind” used in the common law defence of insanity’.¹⁴ As a result the court held that a state of drug-induced psychosis will not give rise to the defence of insanity. In the instant case the court held that as the psychosis was brought about by means of an external agent voluntarily consumed the accused was not entitled to raise the defence. In particular, as the accused’s psychosis had arisen due to drug use, it did not fit the definition of mental impairment which, following the common law, required the illness to be a disease of the mind.¹⁵ Consequently, in the absence of the defence of mental impairment the accused was sentenced to 15 years imprisonment for murder.¹⁶

Given that the use of such an intoxicant in such cases is voluntary and advertent, courts in those situations have been reluctant to find the relevant defendants non-responsible. By refusing to recognize a state of non-responsibility for such culpable behaviour courts are paying heed to what I have referred to in Chapter 3 as the responsibility aspect of the disease of the mind enquiry. In particular courts are reluctant to recognize a state of non-responsibility arising due to the fault or nature of a defendant. This was recognized by Sholl J, who noted that, while there may be cases which are problematic, ‘states of drunkenness of itself, anger or other transient passions, excitability arising from temperament’ have never been regarded as arising from a disease of the mind.¹⁷

The following sections will analyse three approaches to the question of whether the voluntary consumption of an illicit intoxicant leading to a psychotic state should be allowed to give rise to the defence of insanity.

Causal irrelevance

This section will consider the VLRC’s approach to this question. The first part will outline the VLRC’s position while the second will note several objections which have been raised to this view.

VLRC and disease of the mind

In the context of clarifying the current scope of mental impairment, the VLRC turned its attention to the definition of the term ‘disease of the mind’.¹⁸ The VLRC expressed the view that the interpretation of statutory formulations as merely legislative re-statements of the common law result in formulations that are too narrow.¹⁹ In particular, the VLRC objected to the interpretation by the Supreme Court of Victoria in two recent cases of the expression ‘mental impairment’ as found in the Victorian Act.²⁰ In both R v R²¹ and R v Sebalj,²² the Supreme Court interpreted the statutory expression ‘mental impairment’ as ‘merely a legislative restatement of the common law’.²³ The commission argued that adopting a common-law definition of mental impairment would not provide a sufficient level of flexibility in the application of the defence.²⁴ By way of example, the commission cited the case of R v Sebalj.²⁵

The VLRC argued that as a result of the narrowness with which the statutory defence of mental impairment had been defined, the accused had been deprived of the defence. The VLRC held that the cause of an accused’s incapacity was irrelevant to the question of whether a defence should be available to him or her. As a result of the lack of flexibility of the defence, the accused had been denied a defence to which he was entitled. The VLRC noted that the punishment of an individual who lacks the requisite capacities for responsible conduct is an injustice.²⁶

The VLRC expressed the view that fear that a broad interpretation of the legal expression ‘disease of the mind’ or its statutory equivalent ‘mental impairment’ would open the ‘floodgates’ to undeserving accused was unfounded.²⁷ According to the VLRC, the reason why a ‘floodgates’ argument is unfounded is because it is the nature of the requisite incapacities which must result from a mental disorder characterized as a disease of the mind which keep the defence within ‘strict limits’.²⁸ Consequently, it would require an accused to be more than ‘adversely impaired to a material degree by alcohol or drugs’ in order to satisfy the defence.²⁹ In keeping with the rules’ formulation, that which would be required is a lack of capacity to understand the nature and quality of the act or that it was wrong.

The VLRC held that the causal antecedents of an accused’s behaviour are irrelevant to the issue of his or her responsibility. According to the VLRC, where there is a cognitive failure which arises from a disease of the mind which satisfies the elements of the defence then the accused should be entitled to the defence. In order to ensure that there was a sufficient degree of flexibility in the application of the defence the VLRC suggested that the definition of mental impairment should be broader then the common law definition of disease of the mind.

As a result, the VLRC called for statutory intervention to alter the current narrow interpretation and to this end proposed that the following new definition of the expression ‘mental impairment’ be inserted into the Victorian Act:³⁰

7. Definition of ‘mental impairment’ inserted

In section 3(1) of the Crimes (Mental Impairment and Unfitness to be Tried) Act 1997 insert the following definition –

‘“mental impairment” includes, but is not limited to, a disease of the mind’.

By broadening the scope of the defence so as ‘to include, but not be limited to, a disease of the mind’, the VLRC believed that the defence would thereby be available to deserving accused. The next section will critically examine the arguments put forward by the VLRC in support of such statutory intervention.

Notwithstanding the call for statutory amendment by the VLRC, the commission did acknowledge that there are two objections to allowing a person whose psychosis is induced by alcohol or drugs voluntarily consumed to rely on the defence of mental impairment.³¹ First, given that the effects of an intoxicant may only be temporary with no lasting mental malfunction, it would be inappropriate to characterize such effects as a disease of the mind for the purposes of the defence. Second, there is a moral objection to allowing a person to benefit from conditions which he or she has been responsible for bringing about. The VLRC’s response to each of these objections will be considered in turn.

In response to the first objection the commission argued that at common law the duration of a mental disorder will not be determinative of whether or not it is to be characterized as a disease of the mind.³² The commission was correct to take this view. There is no requirement that a state of mental malfunction be permanent in order for the defence of insanity to be established. The defence is available in instances where the state of mental malfunction is permanent as well as in instances where it is only temporary.³³ Subject to what will be said below, all that is required in order for the defence of insanity to be established is that the state of mental malfunction characterized as a disease of the mind caused the relevant incapacities, as defined, at the time of the offence.³⁴ The fact that the mental malfunction was temporary will not preclude such a state from being characterized as a disease of the mind.

Of more interest is the related fact noted by the commission that in Sebalj’s case the accused’s drug-induced psychosis ‘subsequently developed into a schizophrenic illness requiring ongoing treatment’.³⁵ The implication of this view, while not explicitly stated by the VLRC, is that the accused had a predisposition or vulnerability to psychosis which was triggered by drug-use and resulted in a fully fledged schizophrenic illness. Indeed, expert evidence was tendered in Sebalj’s case indicating that it would have been the view of many psychiatrists that the accused suffered from schizophrenia even before the drug-induced psychotic episode.³⁶ However, the commission failed to note that there are problems associated with determining whether a predisposition, or vulnerability, to drug-induced psychosis is indicative of the existence of an underlying pathological infirmity of mind.³⁷ The nature of these problems will be considered during the course of the analysis of the doctrine of settled insanity below.

In particular, the analysis will consider the problems associated with determining whether a predisposition to drug-induced psychosis is indicative of the existence of an underlying mental disorder. Succinctly stated, it will be argued there that there is no necessary causal relationship between an accused’s predisposition to psychosis, a state of psychosis following the voluntary use of an intoxicant and the existence of an underlying mental disorder. Consequently, there is no means of determining whether a drug-induced state of psychosis is sufficient to establish an underlying pathological infirmity of mind and so give rise to the defence. Moreover, it will also be argued that an accused’s lack of control over his or her predisposition to psychosis is not necessarily exculpatory.

The second objection which the commission noted in allowing drug-induced psychosis to be recognized as a disease of the mind was the ‘moral argument that a person ought not to be able to raise the mental impairment defence if they were responsible for causing their condition’.³⁸ The commission recognized that this was an issue which rendered drug-related states of mental impairment problematic. As the commission put it, there is a great deal of difficulty in restricting the notion of responsibility in cases of voluntary drug taking.³⁹ For example, in the instant case, the accused himself was directly responsible for the psychosis as he had originally chosen to engage in the use of drugs. Paradoxically, it was his endeavour to cure himself of his addiction and the method of immediate withdrawal he had chosen in order to achieve this which had ultimately brought on the psychotic episode leading to the death of his girlfriend. Nevertheless, the commission stated that it did not think this should be a ‘consideration in applying the defence of mental impairment’.⁴⁰ The commission argued that where the requisite incapacity is established an accused’s drug-induced state of mental impairment should be sufficient to ground the defence of mental impairment.⁴¹

In particular, the commission was of the view that the court’s ruling on mental impairment in the case of Sebalj failed to acknowledge the defence’s ‘underlying conceptual purpose’.⁴² As expressed by the commission: ‘the purpose of the defence is to ensure that people are excused from criminal responsibility when their cognitive functions are so affected that they are unable to understand what they are doing or that it is wrong’.⁴³ Such a purpose, according to the commission, would preclude taking into account the causal antecedent of the state of impairment. The commission held that what is determinative for the operation of the defence is the cognitive deficiency that gives rise to the requisite incapacities, not how such incapacities came about.⁴⁴ For now, I would argue that adopting the VLRC approach would result in a state of over-inclusiveness which would provide a defence to undeserving accused. By focusing exclusively on the mind of the accused at the time of the offence, without paying due regard to the precise cause of the drug-induced psychosis, all accused who experienced a psychotic response to the voluntary use of drugs would receive the benefit of the defence.

The second objection concerned the moral intuition that it would be unjust to allow a person to benefit from conditions which he or she has been responsible for bringing about. The question of an accused’s responsibility for an act performed while incapacitated where he or she has brought about such incapacity through a voluntary act will be discussed below. It will be argued that not only does the VLRC view expressed above run counter to the current legal position, it is also mistaken. Succinctly stated, the reason why the VLRC is mistaken is that it fails to take into account an individual’s ‘meta-responsibility’ for bringing about a state of non-responsibility.

This section has considered the VLRC’s response to the two objections noted above in allowing a person whose psychosis is induced by voluntarily consumed drugs to rely on the defence of mental impairment. As will be seen both of these objections have given rise to two different approaches to the question of whether drug-induced psychosis should be allowed to ground the defence of insanity. Hence, the following two sections will analyse the VLRC’s response by considering these two differing approaches.

Settled insanity

The first part of this section will begin with an account of the doctrine of ‘settled insanity’ as it is has been developed in certain American cases. The second part will consider refinements to the doctrine as proposed in the work of J. Reid Meloy. The third and final part of this section will then critically examine Meloy’s suggestions in order to determine the utility of the doctrine of settled insanity as an approach in respect of the issues raised by instances of drug-induced psychosis.

Settled insanity

In certain instances courts have held that the chronic use of an intoxicant that produces a state of psychosis operative both before and after the state of intoxication may be characterized as a state of settled insanity, rather than a case of intoxication.⁴⁵ In such cases the chronic use of substances results in a long-lasting or permanent organic brain condition rather than a state of intoxication resulting from the ingestion of a drug or alcohol. It is the long-lasting or permanent nature of the mental condition as distinct from the effects of the intoxicant which determines its characterization as a state of insanity rather than intoxication. For example, in State v Hartfield,⁴⁶ it was held that an accused could plead insanity where his voluntary intoxication by either alcohol or drugs had resulted in a permanent state of mental malfunction which precluded him from knowing right from wrong. Settled insanity is predicated on the idea that certain chronic users of intoxicants experience during the commission of the offence a state of drug-induced psychosis, which is independent of the effects of an intoxicant.⁴⁷ Consequently, the settled-insanity approach focuses on the mental state of the accused both before and after the criminal conduct.

The principal concern with the use of the doctrine of settled insanity concerns the difficulty in distinguishing the point at which a state of mental malfunction arising from the voluntary use of an intoxicant may be said to be symptomatic of an underlying pathological infirmity of mind. For the purposes of settled insanity, instances of drug-induced psychoses that are used to ground a defence of insanity require there to be both temporal proximity between the intoxicant and the psychotic symptoms, as well as satisfying the requirement that the state of psychosis exists independently of the consumption of the intoxicant. As a result there are two aspects to the issue of drug-induced psychosis which the doctrine of settled insanity must answer, one temporal, the other causal. First, what must be the temporal relationship between the use of an intoxicant and any subsequent psychotic symptoms in order for a state of settled insanity to be established? Moreover, if a ‘prolonged or permanent persistence of substance-related symptoms’ is a necessary requirement of a state of settled insanity how is this to be reconciled with the fact that states of temporary insanity excuse?⁴⁸ Second, how are the effects of the intoxicant to be distinguished from the effects of mental disorder? That is, how is a state of intoxication arising through the ingestion of a drug to be distinguished from an underlying pathological infirmity of mind due to chronic drug use?

In respect of the first question a temporal dimension has been viewed by certain commentators as determinative of whether a condition will be characterized as one of settled insanity. For example, according to the American Psychiatric Association’s Diagnostic and Statistical Manual of Disorders:

If the symptoms precede the onset of substance use or persist during extended periods of abstinence from the substance, it is likely that the symptoms are not substance induced. As a rule of thumb, symptoms that persist for more than 4 weeks after the cessation of acute Intoxication or Withdrawal [sic] should be considered to be manifestations of an independent non-substance-induced mental disorder or of a Substance-Induced Persisting Disorder.⁴⁹

The essential feature of a ‘Substance-Induced Persisting Disorder’ is ‘prolonged or permanent persistence of substance-related symptoms that continue long after the usual course of Intoxication or Withdrawal has ended’.⁵⁰ Consequently, according to the DSM-IV-TR, in establishing whether an individual’s psychotic symptoms are the direct physiological effect of substance use or characteristic of a state of settled insanity, the temporal relationship between substance use and a state of psychosis may be determinative.⁵¹

Similarly, Russ Scott and William Kingswell have argued that even if it is accepted that an external factor may cause acute psychosis, this alone will not be sufficient to satisfy the disease of the mind enquiry.⁵² According to the authors, and in keeping with what was said by King CJ in R v Radford,⁵³ what is required for a finding of a disease of the mind is something more than ‘a temporary disorder or disturbance of an otherwise healthy mind caused by external factors’.⁵⁴ As a result Scott and Kingswell contend that drug-induced psychosis should only be characterized as a disease of the mind when the symptoms of psychosis have persisted for longer than 28 days and in the absence of positive urine drug testing.⁵⁵

However, some courts have held that, where psychosis is caused by an intoxicant, the precise time during which the symptoms associated with the psychosis are present will not be determinative of whether such a condition is to be characterized as a disease of the mind. For example, in People v Kelly,⁵⁶ the defendant’s use of drugs during a two-month period resulted in a state of psychosis operative both before and after the murder of her mother. In that instance, the Californian Supreme Court reversed the trial court ruling requiring that the defendant’s state of psychosis be both ‘settled’ and ‘permanent’ before it was recognized as giving rise to the defence of insanity. The Supreme Court held that in order for the defence of insanity to be raised all that was required was that the state of psychosis was ‘settled’ even if not permanent. The court defined a ‘settled’ state of mental disorder as one arising where ‘the mental disorder remains even after the effects of the drug have worn off [regardless of] whether the period of insanity lasted several months or merely a period of hours’.⁵⁷ Consequently, where psychotic symptoms arising from voluntary drug use extend beyond the state of intoxication itself, such a state of psychosis may be sufficient to give rise to the defence of insanity regardless as to whether such symptoms are permanent or not.⁵⁸ For example, in People v Skinner,⁵⁹ the Supreme Court of California considered the case of a defendant who claimed that, as a result of a state of intoxication, he had experienced a state of psychosis which caused him to lack the capacity for criminal responsibility. Expert evidence was tendered by the defendant indicating that such a psychotic response could last for up to eight days after cessation of use. In delivering its judgment the court affirmed that a temporary state of psychosis brought about by intoxicants was not a settled state of insanity as would be expected from chronic use. The court held that: ‘It appears logical that settled must mean fixed and stable for a reasonable duration’.⁶⁰ With respect to the causal issue, the central concern in such cases is how to clinically distinguish a state of intoxication arising through the ingestion of a drug from a long-standing or permanent brain condition arising from drug use? What is needed is a clear indication of when an accused’s state of mental malfunction exists independently of the effects of the ingested intoxicant. The court attempted to answer this question in Skinner by holding that the state of psychosis must ‘not [be] solely dependent on the recent injection or ingestion and duration of the effects of the drug’.⁶¹ However, while requiring that the mental state not be solely dependent on the effects of the intoxicant consumed the court failed in Skinner to provide means by which to ascertain whether this was indeed the case in any given instance.⁶²

The court proceeded to outline the criteria considered relevant to a state of settled insanity which would give rise to an insanity defence:

1. The condition must be fixed and stable;

2. The condition must last for a reasonable period of time;

3. The condition must not be solely dependent on the ingestion and duration of the drug;

4. The condition must meet the legal definition of insanity.⁶³

The discussion of the above criteria has been taken up in the work of Meloy.⁶⁴

Meloy on settled insanity

For Meloy ‘“settled insanity” becomes the legal point at which voluntary behaviour creates a state of mind that negates culpability for criminal behaviour’.⁶⁵ However, according to Meloy, both temporal and causal problems remain with the formulation in Skinner. In relation to the temporal issue Meloy notes that the court in Skinner, in seeking to address the ambiguity inherent in the term ‘settled’, employed two terms, ‘fixed’ and ‘stable’. However, all three terms, ‘settled’, ‘fixed’ and ‘stable’ were synonyms for ‘unchanging’ and were for that reason ‘semantically ambiguous and clinically meaningless’.⁶⁶ In providing such alternatives, the court had merely substituted semantically equivalent words and had failed to create a new distinction aiding clarification.⁶⁷ According to Meloy, what was needed was a clear indication of the requisite ‘period of time’ before which an accused’s condition would be characterized as ‘settled’. While the Supreme Court in Kelly had removed the requirement that the state of psychosis be permanent in order for it to be characterized as a state of settled insanity, it had failed to make explicit the requisite temporal dimension.

In respect of the causal issue Meloy acknowledges that distinguishing the intoxicating effects of an ingested drug from a state of mental malfunction existing independently of the effects of an intoxicant ‘is a clinically very difficult question to answer’.⁶⁸ In particular, Meloy notes that ‘there is no clinical interview technique, psychological test, or central nervous system measure (CAT scan, PET scan, MRI, EEG, etc.) that can retrospectively sort out the various factors that cause a mental state and weigh their contribution, whether drug related or not, to a criminal act.’⁶⁹ A consequence of this uncertainty is that ‘the question would fall, as is often the case when the law reaches and psychiatry attempts to grasp, to the speculation of retained experts’.⁷⁰ In order to remedy the court’s shortcomings in Skinner in respect of both of these issues Meloy proposes ‘that courts turn to the scientific literature for direction [in order] to formulate a judicial principle that can be applied to the facts in any one particular case’.⁷¹ So as to formulate such a general principle Meloy uses by way of example the case of individuals who chronically use psycho-stimulants such as amphetamines and cocaine. Motivating Meloy’s choice of example is the fact that the use of such drugs will give rise to delusions, the most paradigmatic symptom of psychosis the archetypal instance of mental illness.⁷²

Meloy begins by citing five studies that support the view that ‘subjects who become paranoid while using psycho-stimulants are predisposed to the development of such psychosis in the absence of pharmacological stress’.⁷³ One study cited found that drug users who developed psychosis had pre-morbid histories and symptoms comparable to those of schizophrenic patients, while a comparison group of drug users who did not develop such symptoms used drugs without psycho-mimetic properties.⁷⁴ Another study indicated that acutely psychotic subjects who had used hallucinogens within three years of admission were more sensitive to psychosis if they had a family history of mental illness.⁷⁵ A further study found that a diagnosis of paranoid schizophrenia was more likely to occur amongst those patients with schizophrenia who abused cocaine than amongst those patients with schizophrenia who did not.⁷⁶