The Insanity Defence: Is ‘Wrongness’ Legal or Moral?

‘Madness’ became a complete defence regarding criminal charges as early as the time of Edward III in the 14th Century. In the following centuries, prominent legal treatise shifted from the ‘knowledge of good or evil’ test, to the ‘wild beast test’ in the eighteenth century. Courts then settled on the M’Naghten rules in 1843, by virtue of Daniel M’Naghten’s case, following an attempted assassination on Prime Minister Robert Peele. M’Naghten was acquitted by reason of insanity (NGRI) and sent to Bethlehem hospital, creating mass public dissatisfaction. Lord Tindal CJ responded with the outlined rules of insanity: “it is for the defence to prove that, because of a defect of reason, stemming from a disease of the mind, the defendant either; did not know the nature and quality of his act; or did not know that his act was wrong”. The italicised element of the rules as aforementioned above, namely, the wrongness limb, will be the motivation behind this blog.

The M’Naghten rules cannot provide a fair defence to defendants who, acting under a delusion, believed they were doing the ‘right thing’, as ‘right’ in the eyes of the law, is acting in accordance with the law, but ‘right’ to many defendants, is founded on morality. For the purposes of my response, I will focus on why ‘doing the right thing’ in law, and in morality, is a controversial demarcation with regards to the rules of insanity. I will then explain why a shift to moral wrongness would be a fair and just result, more so than the current state of the law.

The Law of The Land

In attempt to provide clarity regarding this ambiguous limb, it was initially stated that “if that act was, at the time, contrary to the law of the land, he is punishable”, and will not be excused via an NGRI. This was initially addressed in the case of Codere, and a strict interpretation was subsequently applied in Windle, revisited in Johnson. Within Windle, the defendant had been suffering from folie à deux, a form of delusional insanity. Windle famously stated, “I suppose they will hang me for this?”, after administering his wife with a fatal dose of aspirin. From this statement it is clear that Windle knew what he was doing was illegal, yet considered it to be the ‘right thing’ morally.

The appellant’s council asserted that ‘wrong’ under M’Naghten, means morally wrong, and not contrary to law. If this was implemented, Windle would have been provided a defence, as he was under the delusion that he was ‘doing the right thing’ in accordance with his morals, irrespective of law. The court, however, observed that it must not take into consideration the moral boundaries of the act, but whether it was right or wrong in the eyes of the law. Windle was thus denied an NGRI. It then became common thought that “there is only one kind of right and wrong: the right is when you act according to law, and the wrong is when you break it”.

The ‘Right’ Thing

‘Doing the right thing’ has two alternative interpretations, namely that of law and that of morals, with two very different outcomes for defendants such as Windle. In the more recent case of Johnson, Mackay concluded that the “the wrongness issue was being treated in a liberal fashion by all concerned”. He further highlighted that 68 psychiatric reports from 2001 referred to moral wrongness, concluding that his research supports the common question of psychiatry: if the delusion experience by the defendant turned out to be reality, would their actions be justified? In practice, psychiatrists are advocating an insanity defence on the basis that the defendant deemed their acts to be morally justifiable, disregarding knowledge of the law.

Goldstein opines that a mentally ill individuals’ way of ‘knowing’ differs from that of a normal person, comparing it to the knowledge of children. The M’Naghten rules confine its inquiry to the defendant’s cognitive capacity; this is unfairly testing surface cognition, not responsibility. Critiques of this nature date back to 1874, where psychiatrist Maudsley stated it to be “obvious that knowledge of right and wrong is different to the knowledge of an act being contrary to law of the land”. He held it to be concrete that an insane person may do an act that she knows to be contrary to law, because she believes it to be right, as “he is a law unto himself, and deems a duty to it”. Knowing an act to be wrong is one concept to a neurodivergent agent,  but is a very different matter to those who are not of mental soundness. For many individuals such as Sutcliffe, this is a public service, and they are not realistically motivated by the laws that would influence a regular man.

The ‘Yorkshire Ripper’

In 1981, Peter Sutcliffe, also coined the ‘Yorkshire Ripper’, was charged with the murder of 13 women. Sutcliffe was suffering from hallucinations as a result of florid schizophrenia. He believed that God had assigned him the mission to rid the world of prostitutes, but his apparent mental illness fell on deaf ears, and he was sentenced to Parkhurst Prison. In this case, akin to cases such as Windle and Yates, Sutcliffe was under the delusion that he was doing ‘the right thing’ morally, disregarding law entirely.

It would be petty legalism to question Sutcliffe’s knowledge of the law – the conflict for the defendant lay at a higher moral threshold. As a result, this position of illegality has been labelled a ‘sterile, armchair logicians’ test’. For wrongfulness to remain isolated in the sphere of merely a legal manner, is both shockingly restrictive and scientifically ignorant. The Butler Committee echoed these worries, stating that ‘knowledge of the law is hardly an appropriate test’ to refer to moral responsibility. By preventing mentally ill defendants from receiving the rehabilitation they so desperately require, this limb far from results in justice. An alarming number of mentally ill defendants are then incarcerated amongst the general population, preventing the very thing the defence set out to do.

Creating A ‘Fair’ Defence’: Revitalise the Wrongness Limb

How then, could M’Naghten rules provide a fair defence to defendants who acted under a delusion, believing they were doing ‘the right thing’? M’Naghten can be reformed via threefold options; in reference to the ‘right thing’, the court could refer to social, personal, or moral wrongness.

Regarding the former, social wrongness is to know the act is contrary to moral belief of the people in that society. This seems more intuitive than legal wrongness, but in practice, illegality is a clear indicator of social disapproval, therefore there would be very few agents that knew an action is illegal, but unaware that it was contrary to social acceptations. On the account of personal wrongness, the defendant would not regard his act as wrong in accordance with his own standards. This interpretation runs into an array of issues, specifically, the defendants’ standards may be drastically different to those of the society, and open the floodgates to many who desire to escape liability.

For a defendant to know their act is immoral, they need not know of what others believe to be of moral status. Instead, it is for the defendant to know whether the act itself entails a certain property that obtains the moral status of being wrong. For example, a defendant cannot know that murder is morally wrong, unless they know that the murder holds a property that makes that act wrong, such as causing unjustifiable harm to the victim.

Lord Goddard in Windle aims to justify the decision made on the wrongfulness limb; “the court of law can only distinguish between that which is in accordance with the law, and that which is contrary to it. He emphasised that a morality-based test would be ‘unfortunate’ if we merely left it up to the jury to decide. If we endorse moral anti-realism, subjective morals can lead to socially contingent, problematic, and bias idiosyncratic judgements. However, His Lordship is stating that the courts cannot make decisions of morality, but this does not necessarily hold whether the defendant can.

In order to apply moral wrongness, judges and juries would be required to ask normative questions, but the answers are rarely controversial. This use of morality has been mirrored in Australian and Canadian courts. The Australian High Court in Stapleton held that if a defendant believed his act to be morally right, he is entitled to an acquittal on the basis of insanity, regardless of whether or not he knew it to be illegal. In their judgement, they outright expressed that Windle had been wrongly decided.

The Canadian courts have equally favoured a ‘moral wrongness’ interpretation of M’Naghten’s second limb. In Chaulk, the court provided an example parallel to Sutcliffe’s case; a person who kills in the moral response to a divine order, believing it to be right, ought to be excused. In the Canadian case of Swain, the defendant’s insanity plea was successful, founded on the Chaulk’s interpretation of ‘wrongness’ – providing a more fair and just defence for the mentally ill than the archaic M’Naghten rules.

My Final Comments

A defendant who acted under a delusion, but thought they were doing ‘the right thing’ will not be fairly defended by M’Naghten. M’Naghten cannot provide a defence where the agent knew the act to be illegal, regardless of morals. This acts as a catalyst of injustice; mentally ill defendants are less likely to be motivated by the law of the land, and cannot comprehend binary knowledge like those that are suitably compos mentis. This remains the Achilles heel of the insanity defence, a vulnerable element of criminal law. To hold wrongfulness as a legal concept is established on untenable grounding, and it is not ‘fair’ on defendants who believed they were ‘doing the right thing’ under a delusion. The Court in Windle was misled in their definition of the wrongfulness limb, and the English and Welsh courts ought to follow suit with Australia or Canada in order to rectify this injustice. 


Published by Harriet Leslie

Hi! I'm Harriet. I am a writer for numerous websites, with a first-class BA in Philosophy and an MA in Medical Ethics and Law. I hope you enjoy my mini introductions to all things philosophy and ethics, many of which have been essays for academic purposes.

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