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Psychiatry’s fight for a place in defining criminal responsibility

Psychiatrists wanted people found ‘not guilty by reason of insanity’ to be dispatched to places like the Asylum for Criminal Lunatics Broadmoor. Illustrated London News, 1867/ Public domain, Wikimedia Commons

Are people with “diseases of the mind” responsible for their criminal acts?

In the latest article in our series Biology and Blame, Ivan Crozier looks back at how psychiatrists tried to carve out a role for their profession in determining criminal responsibility.


Prior to 1760, medical opinion was not used in insanity defences; rather, the use of psychiatric evidence in court was the result of a long struggle between the relative authorities of lawyers and psychiatrists, in which the law held a dominant position and was slow to change.

Following the 1843 trial of Daniel M’Naghten for killing Edward Drummond, debate in the House of Lords held 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.

This ruling has remained the basis for understanding criminal responsibility in many jurisdictions since. Establishing responsibility is one of the basic principles of the law, so the role of psychiatric expertise in assessing “disease of the mind” became fundamental.

The M’Naghten Rules were far from the first legal pronouncement on criminal responsibility, but for the growing field of psychiatry, the ill-defined phrase “disease of the mind” was a subject over which it felt it had some authority.

At almost every opportunity (giving expert testimony, for instance, or reporting on crime in psychiatric journals or theorising about legal insanity), psychiatrists criticised the emphasis on the cognitive limb of the Rules (that the defendant knew what they were doing, and that it was wrong).

They maintained this cognitive understanding of mental incapacity was far too narrow when contrasted with the growing psychiatric concepts of “diseases of the mind”.

Indeed, most psychiatrists believed they should be in the position to define the mental illness under which the defendant was labouring, rather than adhere to a legal definition they thought irrelevant.

The law prevails

Artist sketch of Daniel M'Naughtan and an engraving of his signature dated March 4 1843, from the Scottish Reformer s Gazette. Public domain/Wikimedia Commons

But not being responsible for one’s actions was (and remains) strictly a legal, not medical, problem. And the law had only to satisfy itself that the defendant would not be executed without understanding their crime.

The burden of proof of non-responsibility lies with the defence. The role of psychiatric evidence might be assumed to carry much weight in this but, in practice, the law maintains its powerful position because it defines the acceptable terms of evidence.

To have evidence about a defendant’s responsibility accepted, psychiatrists had not only to establish that he or she was insane, but also that the insanity met narrow legal requirements. The profession pushed itself into legal debates, criticising legal judgements on insanity and giving evidence that fitted the defendant to the M'Naghten Rules by explaining their conduct as a product of a “disease of the mind”.

And there was significant agitation to bring the law into line with biological understandings of mental incapacity. Brain damage, epilepsy, “lesions of the will”, “degeneration”, irresistible impulses and other psychiatric concepts were (not always successfully) enrolled to explain a defendant’s non-responsibility.

Rather than being sent to the gallows, psychiatrists wanted those found “not guilty by reason of insanity” to be dispatched to new, specialised criminal lunatic asylums, such as Broadmoor (opened 1863).

Gaining ground

The efforts began to pay off; increasingly, judges listened to psychiatric evidence. In 1883, Victorian England’s premier legal theorist, James Fitzjames Stephen, held that:

If it is not, it ought to be the law of England that no act is a crime if the person who does it is at the time prevented either by defective mental power or by any disease affecting his mind from controlling his own conduct, unless the absence of the power of control has been produced by his own default.

Outfits used for people in criminal lunatic asylums. Curious Expeditions/Flickr, CC BY-NC-SA

Although welcomed by psychiatrists, Stephen’s pronouncement did not enter the English law until its modified introduction in the Homicide Act of 1957.

In 1896, as part of psychiatry’s challenge to the Rules, a committee of the Medico-Psychological Association (later the Royal College of Psychiatrists), recommended that in trials where the defendant’s mental condition might play a role, judges ask juries to question:

a) Did the prisoner commit he act alleged? b­) If he did, was he insane at the time? c) If he was insane, has it nevertheless been proved to the satisfaction of the jury that his crime was unrelated to his mental disorder?

Unsurprisingly, the proposal favoured the weight of psychiatrists’ expert evidence about defendants’ mental state. In a (delayed) response to these recommendations, the British Medical Association formed the medico-political sub-committee on crime and punishment in 1913.

The subcommittee held the M’Naghten Rules should be kept in substance, but that Stephen’s 1883 clause concerning “irresistible impulse” be added, so that a person shouldn’t be held to be responsible if prevented by a disease of the mind from controlling their behaviour unless the lack of control is their own fault.

James Fitzjames Stephen in 1886. Bassano/Public domain via Wikimedia Commons

Close but…

The government’s response to these medical challenges was to found the Atkin Committee to report on Insanity and Criminal Responsibility after the high-profile trial of Ronald True (1922). The Committee rejected the Medico-Psychological Association position, but it agreed with psychiatrists that mental disorders progressively erode the capacity for self control.

It also agreed that M’Naghten didn’t always produce the just response to insanity. Essentially, it accepted mental disease excused guilt but was loath to turn this into a psychiatric decision. It noted:

the difficulty of distinguishing some of such cases [where the act is not voluntary] from cases where there is no mental disease, such as criminal acts of violence or sexual offences where the impulse at the time is not merely uncontrolled, but uncontrollable. The suggested rule, however, postulates mental disease, and we think that it should be made clear that the law does recognise irresponsibility on the ground of insanity where the act was committed under an impulse which the prisoner was, by mental disease, in substance, deprived of any power to resist.

So, following Stephen, the Atkin Committee sided with the BMA and recommended the introduction of an irresistible impulse clause to the laws of criminal responsibility.

But a report doesn’t make the law, and a reformist judge’s 1923 attempt to raise a bill reflecting the Atkin Committee’s recommendations before the House of Lords failed. The opportunity to bring the laws of criminal responsibility into line with the medical and psychiatric opinion of the day was lost as the Lords held that will and cognition, rather than a psychiatric understanding of “disease of the mind”, remained central to responsibility.

Although much of the urgency for dealing with mentally ill defendants decreased after the removal of the death penalty, M'Naghten still frames much of the legal understanding of the effects of diseases of the mind.


This is the third article in our series Biology and Blame. Click on the links below to read other pieces:

Part one – Genes made me do it: genetics, responsibility and criminal law

Part two – Irresponsible brains? The role of consciousness in guilt

Part four – Looking for psychopaths in all the wrong places: fMRI in court

Part five - Why shouldn’t addiction be a defence to low-level crime?

Part six – Natural born killers: brain shape, behaviour and the history of phrenology

Part seven - Put down the smart drugs – cognitive enhancement is ethically risky business

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