8.1 Background to the Insanity Plea

There is a long-standing tradition in most legal systems that allows two kinds of excuses as a justification for breaking the law. The first is the argument that the illegal act was committed in ignorance. Someone who had shot another person might claim it was an accident because he or she didn’t know the gun was loaded. Or one person might admit to poisoning another after cooking a meal, and claim that he or she didn’t know that rat poison was kept in the jar marked ‘food colouring’. The excusing of children from legal culpability is derived from this area, and when a child is found to have committed a serious offence it is assumed that he or she didn’t know any better.

The second kind of excuse occurs when the perpetrator can claim that he or she was compelled to act in a particular way. Self-defence and extreme provocation come into this category. Acts committed under duress, as well as behaviour that is motivated by extremes of emotion, might also be excused on the grounds of compulsion.

There is a long history of excusing people who are deemed to be insane at the time of committing a crime, on one or the other, or both, of these grounds. Roman law of the later Empire period excused insane people because an analogy was drawn between them and children. Ancient Hebraic law ‘recognised that deaf-mutes, idiots and minors were not responsible for their actions’ and ‘[a]ncient Mohammedan law applied punishment only to individuals who have attained their majority, and who are in full possession of their faculties’.[1]

In modern times, countries with legal systems derived from British law have developed a test for insanity which excuses legal culpability when the person, at the time of committing the crime, is believed to be unaware of the difference between good and evil. The legal precedent which establishes this test is known as the M’Naghten case.[2]

In England in 1843 Daniel M’Naghten assassinated Edward Drummond, the private secretary of the Prime Minister. M’Naghten claimed to believe that a number of people, including the Prime Minister, were persecuting him in various ways. At his trial M’Naghten successfully defended his actions on the grounds of insanity, but after the trial many people still believed he might only have been feigning his madness. As a result the judges in the case were asked to appear before the House of Lords and explain the test of insanity they had applied to M’Naghten. The answer supplied by the judges has since become the basis for a test of criminal insanity:

To establish a defence on the grounds of insanity, it must be conclusively proved that, at the time of the committing of the act, the party accused was labouring under such a defect of reason, from the 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 what he was doing was wrong. (Regina v. M’Naghten, 10 Clark and F. 200, 8 Eng. Rep. 718 (1843)).[3]

The so-called M’Naghten test soon became established in English-speaking countries as the principle test of legal insanity, but it also came under persistent criticism because it was thought to be too narrow in its definition. This was because it only covered the traditional defence of ignorance and did not provide a defence for a person who was aware of the nature of the act, and aware that it was wrong, but all the same was compelled by mad impulses to act contrary to the law.

In the United States this controversy finally produced a definition by the American Law Institute which incorporated both defences:

(1) a person is not responsible for criminal conduct if at the time of such conduct as a result of mental disease or defect he lacks substantial capacity either to appreciate the criminality of his conduct or to conform his conduct to the requirements of the law.[4]

A more recent trend is to define ‘mental illness’ in mental health legislation so that the interpretation of the condition is a legal matter as well as a medical matter. The terminology of criminal insanity is replaced with ‘mental illness’. A person who at the time an offence was committed is deemed to have been mentally ill, according to the legal definition of mental illness, is thus not to be held responsible for criminal acts.

Under most modern mental health legislation, a medical practitioner who encounters a person manifesting positive symptoms of schizophrenia, and who is thought to be dangerous, disruptive, or likely to deteriorate, is legally authorised to have the person incarcerated in a mental hospital. This is where the existence of the insanity plea is important as a background motivator for the medical impositions that are placed on the person.

Ostensibly the doctor is free to choose to have the person incarcerated or not, according to the best interests of the patient. But in many respects a doctor involved in psychiatric matters is simply an agent of social control. As such, the doctor is required to consider the social and legal consequences of allowing the person with schizophrenic symptoms to remain free. Having diagnosed the person as schizophrenic, and therefore as being mentally ill in a legal sense, the doctor has in effect provided the person with a legal excuse to get away with murder, or any other crime, in the future.

From the criminal justice perspective, therefore, a diagnosis of serious mental illness, without a subsequent imposition of control, has to be seen as a sign of professional irresponsibility. The precautionary control of people who could possibly invoke an insanity plea is a necessary social-control task that goes with the job of doctor.

A recent case in the United States is a good illustration. The 10 October 1998 edition of the New York Times had a front page story with a headline that tells it all—‘Killer Sues His Therapist and Wins $500,000’.[5]

Wendell Williamson was a law student at the University of North Carolina when he was first directed to attend a consultation with Myron B. Liptzin, the head of student psychiatric services, after he disrupted a class by claiming he had telepathic powers. Liptzin diagnosed Williamson with delusional disorder grandiose and prescribed neuroleptic medication. After eight consultations, Liptzin informed Williamson that since he was soon to retire Williamson should find another psychiatrist. Williamson did not follow Liptzin’s advice, and instead of finding another psychiatrist he simply stopped taking his medication.

Eight months after his last contact with Liptzin, Williamson shot two men in the street without provocation. He was diagnosed with paranoid schizophrenia, and at his trial was found not guilty on the grounds of insanity. At a subsequent trial he was awarded $500,000 in damages against Liptzin, his former psychiatrist. The jury believed that Liptzin had not correctly perceived the seriousness of Williamson’s disorder and had not imposed the necessary control measures. A newspaper report said Williamson claimed that

the verdict in the civil case showed that he and the people he killed were all victims of Dr. Liptzin’s failure. ‘The murders would not have happened if Dr. Liptzin had done his job properly.’ Williamson testified at trial of his suit last month, telling the jurors that Dr. Liptzin ‘had more control over the situation than I did.’[6]

Williamson’s success with this unlikely argument is an unequivocal message to psychiatrists that the justice system expects them to impose precautionary control measures on anyone they encounter who is likely to commit a crime and escape criminal liability with an insanity plea. This type of message is particularly disturbing for critics of medical psychiatry because it reinforces the expectation of an authoritarian imposition of the medical model. Thomas Szasz and Jeffrey Schaler are leading critics of medical psychiatry, and they both responded within a few days of the Williamson story with letters to the editor.

To the Editor:

That killers can successfully blame their therapists for their actions (front page, Oct. 10) is the consequence of the fiction of mental illness and the junk science of psychiatry that it supports. Although lawyers, psychiatrists and society conspire in the twin charades of civil commitment and the insanity defence, the main culprits are the mental health professionals. If they believed in personal responsibility rather than in mental illness—and rejected the practices of depriving innocent people of liberty and excusing guilty people of crimes—we would be spared the spectacle of criminals’ being acquitted of crimes and collecting damages as if they were the victims of untreated diseases.

THOMAS SZASZ, M.D. Syracuse, Oct. 10, 1998

The writer is professor emeritus of psychiatry at SUNY Health Science Center.[7]

To the Editor:

Why did a jury hold a psychiatrist, Myron B. Liptzin, accountable for Wendell Williamson’s murderous acts (front page, Oct. 10)? Because psychiatrists invented and perpetuate the myth of mental illness. As long as people believe in mental illness as a cause for behaviour, those who receive such a ‘diagnosis’ will be exculpated—and someone else will be culpable.

Since psychiatrists removed the blame, it is only fitting that they should be saddled with it.

JEFFREY A. SCHALER, Silver Spring, Md., Oct. 10, 1998

The writer is an adjunct professor of justice, law and society at American University.[8]

Despite the numerous doubtful applications of the insanity plea such as Williamson’s, the concept is deeply entrenched in legal custom and most people still agree that it should be available. But its continued existence is presenting acute problems for civil liberties. In the modern context, any positive effect it might have for human rights is disproportionately counter-balanced by a negative effect as large numbers of innocent people are made victims of precautionary psychiatric controls.

Some comparative figures might be useful to illustrate this point. In New South Wales in 1996, for instance, there were ten people who were tried for criminal offences and who were found not guilty by reason of mental illness. A further three people were found mentally unfit for trial. These thirteen people who escaped criminal liability in that year can be compared to 7601 involuntary admissions to mental hospitals, 2095 Community Treatment Orders and 167 Community Counselling Orders, totalling 9863 involuntary impositions in the same legal jurisdiction in the same year.[9] 

All of these involuntary impositions required a medical opinion that the people involved were at risk of causing serious physical harm to themselves or other people. But what was the real risk? For every case where a person did successfully evade criminal liability on the grounds of mental illness there were some 760 occasions on which people had their human rights violated as a precautionary measure.


[1] Michael S. Moore, ‘Legal Conceptions of Mental Illness’, in Baruch A. Brody and H. Tristram Engelhardt, Jr., eds., Mental Illness: Law and Public Policy, D. Reidel Publishing, Dordrecht/Boston, 1980, p. 27.

[2] Jerome Neu, ‘Minds on Trial’, pp. 81–82.

[3] Moore, op. cit., p. 28.

[4] Ibid., p. 30.

[5] William Glaberson, ‘Killer Sues His Therapist and Wins $500,000’, New York Times, 10 October, 1998, p. 1.

[6] Ibid.

[7] Thomas Szasz, letter to the Editor, New York Times, 14 October 1998.

[8] Jeffrey A. Schaler, letter to the Editor, New York Times, 14 October 1998.

[9] Mental Health Review Tribunal, Annual Report , 1996, pp. 37–57.