Common-law defense of insanity is governed by the so-called M’Naghten rules, which were developed in the UK's courts. The rules were a reaction to specific events that took place in 1843/2000. On 20 January that year, Prime Minister Peel's Private Secretary Edward Drummond was on his way toward Downing Street when he was approached by wood turner Daniel M’Naghten, who drew a pistol and fired it into Drummond's back. Drummond died a few days later of his wounds. M’Nagthen was brought to trial for “the willful murder of Mr. Drummond,” but during the court case it became evident that he suffered from delusions of persecution. The jury ended up finding M’Naghtan not guilty on the grounds of insanity. The acquittal of M’Naghten raised public controversy in the press and Parliament and questions about the scope of the insanity defense was put to judges of the Queen's Bench. The answer to these questions became enshrined in law as the M’Naghten rules and stated: “that to establish a defense on the ground of insanity, it must be clearly proved that, at the time of committing of the act, the party accused was laboring under such a defect of reason, from diseases 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” (Richard) It should be added that Daniel M’Naghten did not escape incarceration, he spent the rest of his life in mental asylums.
The M’Naghten rules form the basis for common-law and most statutory formulations of the insanity defense in Australia and other Commonwealth jurisdictions. The M’Naghten rules, however, have also been subject to serious criticism. Many of the controversies have centered around ambiguous terms such as “defect of reason” and “diseases of the mind.” Proposed revisions of the M’Naghten formulation have, consequently, been put forward by law scholars, psychologists and psychiatrists.
Mental State Defences in Criminal Law by Steven Yannoulidis of Monash University examines the problems associated with the M’Naghten rules and insanity defences. Yannoulidis focuses predominantly on mental state defences in Australia but he also includes examples from Ireland, New Zealand, South Africa, the UK and the USA. The book draws on a large body of empirical evidence and sheds light on key issues such as the doctrine of automatism (mental conditions that cause an individual to act in an involuntary fashion), understandings of diseases of the mind, and tensions between individual justice, judgment of responsibility and societal protection.
One of the most interesting chapters in the book deals with the question of drug-induced psychosis. As Yannoulidis notes, the issue of whether someone who has suffered from drug-induced psychosis can use the defense of insanity is a pressing legal question which has arisen in several recent criminal court cases in Australia (Carrol et al., 2008). The chapter analyses various issues that occur in attempts to raise non-responsibility for criminal conduct performed subsequent to voluntary drug use resulting in psychosis. Yannoulidis outlines three broad approaches to this problem: liberal, conservative and intermediate. The central issue in cases of drug-induced psychosis is whether the accused can be considered responsible for causing his or her condition. With a liberal approach, causal antecedents of an accused's behavior are irrelevant to the question of his or her responsibility. If there is a cognitive failure which arises from a disease of the mind then the accused should be entitled to the defense. The second, intermediate, approach to the issue of drug-induced psychosis as a disease of the mind is referred to as “settled insanity,” which holds an accused non-responsible where a state of mental malfunction is diagnosable independently of drug use (p. 86). The third, conservative, approach holds an accused responsible where he or she, through culpable behavior (drug use), causes a state of mental malfunction which results in the relevant incapacities. Consequently, the accused will not be given a defense of insanity. Yannoulidis backs up this latter approach: “where an accused has brought about his or her own incapacity in a rational and voluntary fashion, he or she should be held responsible” (p. 121). Yannoulidis, however, is aware of the fact that this approach does not settle all questions. One problem is that drug-induced psychosis can occur not only in association with drug consumption, but also with drug withdrawal. Furthermore, it can be brought on by prescription and over-the-counter medicines as well as by use of illicit drugs. This raises a number of questions. Should an accused who was trying to quit illicit drug use or a patient following a physician's advice be held responsible if this conduct led to criminal acts? Would a person taking medication and a person refusing to take medication be equally responsible if they committed violent offences? The conservative approach breaks with the liberal-medical conception of mental disorders in which the patients are seen as non-responsible for their disorder, but it leaves open questions regarding responsibility and the foreseeable consequences of drug use in its various forms.
Mental State Defences in Criminal Law offers interesting discussions on the issue of drug-induced psychosis and questions related to the M’Naghten rules. It will find most readers among legal scholars from common law countries, where the M’Naghten rules are contested and debated.
