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In criminal law, a crime is treated as a unit, which has two components or essentials: Actus Reus and Mens Rea. While Actus Reus is the explicit or physical act done,Mens Rea is the mental state of a person committing the crime. He should have understood the nature of his act, and its consequences. To establish a crime and for criminal responsibility to arise, both components must be present.

Defenses like insanity, minority, provocation, etc. are employed to establish that the guilty state of mind was lacking in a person. When a perpetrator does not realize the gravity of his act, nor in a mental capacity to assess it, cannot be held entirely responsible for the “crime”. And punishing a person, who is not responsible for the crime, is a violation of the basic human rights and fundamental rights under the Constitution of India.  Hence, it is generally admitted that incapacity to commit crimes exempts the individual from punishment.[i]

In this article, our primary concern would be to analyze the defense of insanity, its determination, development and implications. Insanity is referred to as lunacy or unsound mind, a mental abnormality, disorder of mind, that is, an insane person cannot think and act as a normal human being. He does not possess the rationality as possessed by an average individual. It is called ‘non compose mentis.’ (possessed of a sound mind.)

As we know, to determine the state of mind of a person is not an easy task. Whether he was perfectly capable to understand the nature of his actor was mentally unsound in reality, determines his legal stance.


One of the primary tasks in pursuance of granting this defense is its identification, that is achieved by means of a test. There were various tests used to declare a person legally insane such as Wild Beast test, The Insane Delusion test,and “test of capacity to distinguish between right and wrong.” These three tests laid the foundation for the landmark Mc Naughtenrule. This Mc Naughten rule became a legendary precedent for the law concerning the defense of insanity. Even, in India, insanity defense law, Section 84 IPC is solely based on the Mc Naughten rules. Since it is drafted, no substantial changes have been made.

The Mc Naughten rules, which are the continuing measure of insanity, incorporate a classical, scholastic, intellectual thought which is a century old.They were developed after the trial of Daniel Mc Naughten in 1843, who was acquitted of the murder of Edward Drummond, whom he had assassinated believing him to be Prime Minister Robert Peel. Mc Naughten was described as an “extreme paranoid schizophrenic” who was “entangled in an elaborate system of delusions” which caused him to believe that the Prime Minister was responsible for all his personal and financial life problems.Schizophrenia is basically understood as an aberration inducing a kind of split personality. The Rule or testprimarily focuses on whether a perpetrator knew the nature of the crime or understood right from wrong at the time it was committed. The rule states:

“Every man is to be presumed to be sane, and … that to establish a defense on the ground of insanity, it must be clearly proved that, at the time of the committing of the act, the party accused was laboring under such a defect of reason, from disease of mind, and 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.”[ii]

However, this rule clearly cannot be relied upon entirely. To determine one’s cognitive abilities cannot be done through a mere formula. What about the individuals who were conscious about the commitment and nature of their act, yet unable to deal with their impulse to commit them? The rule doesn’t define a middle ground for them, pushing them across into the que of ‘criminals’. The Law Commission, while revisiting Section 84, IPC, concluded unequivocally that an “irresistible impulse” could not find a place in the existing provision since it is not strictly considered “insanity”, and that its inclusion within Section 84 would make the trial of the mattervery difficult for the judges.

The crucial point of time for determining the state of mind of the accused is the time when the offense was committed.  Other facts which also needs to be given importance are: Motive for the crime, the previous history as to mental condition of the accused, the state of his mind at the time of the offense, and the events immediately after the incident that throw a light on the state of his mind[iii].

It should have been clear by now that, that to take the defense of insanity, legal insanity has to be established and not medical insanity. Medical insanity deals with the person’s previous and present conduct and behavior, whereas legal insanity implies that wrong-doer must be under unsoundness of mind at the time of the incidence or crime, and he does not know its nature and affects.In one of the landmark decisions, in the case of Surendra Mishra versus State of Jharkhand[iv], the Supreme Court has stated that an accused who seeks acquittal from liability of an act under Section 84 of the IPC is to prove legal insanity and not medical insanity.

Position in India

The philosophical basis of exemption of insane offenders from criminal liability is perhaps traceable to the functional limitations of the retributive and deterrent theories of punishment which inspire the provisions of the Indian Penal Code[v]In India, Section 84 of Indian Penal Code (IPC) deals with the “act of a person of unsound mind” and discusses insanity defense. The principle of “Furiosinullavoluntasest” lies at the core of this provision. This means, that mentally impaired persons cannot validly sign a commit their will. Section 84 reads as:

“Nothing is an offence which is done by a person who, at the time of doing it, by reason of unsoundness of mind, is incapable of knowing the nature of the act, or that he is doing what is either wrong or contrary to law.”

However, this concept isn’t as easy to implement as it appears in its literal meaning. One twisted case of insanity is, epilepsy. In most cases, the Court hasn’t included epileptic fits in the ambit of insanity. But if they become very frequent, they might lead to insanity. In State of Madhya Pradesh v Ahmadulla,[vi] the accused was a epileptic, yet the Supreme Court refused to grant the defense. This was because the facts of the case showed that the accused bore ill will towards the deceased, and the crime seemed perfectly planned and was carried out in the dark hours, and it could be concluded that while the commitment of the crime, he was in his perfect senses.

Another such case is of Somnambulism, the disorder of sleep-walking. In the twisted case of Pappatthi Amma[vii]l, decided by the Madras HC, the accused was given the defense of insanity, including sleep-walking within the scope of Section 84. In this case, the accused had recently given birth to a child, jumped into a well with the baby in the night. While the accused was rescued, the infant drowned and died. Murder charges were pressed on the mother, and she pleaded that she was totally unaware of her action during sleep-walking.


The subject of criminal liability and mental illness is still a disputed issue in criminal jurisprudence. However, significance lies in the fact that criminal jurisprudence has evolved to lay more emphasis on rehabilitation and reform rather than punitive retribution. It is an understandable fact that the theories of deterrence and retribution will fail to do any good against a person who had no mental capacity to assess his act. It is also clear that granting and assessing the defense of insanity isn’t a straight-jacket formula.

The medical discipline describes the patient’s mental status on a continuum that ranges from extremely ill to completely healthy. However, the legal language is clearly categorical in nature, either criminally responsible or not responsible.[viii]The gist lies in the fact, that the Court has a greater task in hand than just to determine “guilty” or not “guilty”. To make sure that an innocent doesn’t find his way to the prison instead of a rehab, or a perfectly sound person doesn’t exonerate himself, twisting the defense to his misuse, and more importantly, courts are concerned with the protection of the society from the possible dangerousness from these patients.

[i]Gaur KD. Textbook on the Indian Penal Code. New Delhi: Universal Law Publishing; 2009.


[iii]Math, Suresh Bada, Channaveerachari Naveen Kumar, and Sydney Moirangthem. “Insanity Defense: Past, Present, and Future.” Indian Journal of Psychological Medicine 37.4 (2015): 381–387. PMC. Web. 21 July 2018.

[iv]2011, 11 SCC 495

[v] Sharma K.M, Defense of Insanity in Indian Criminal Law, Journal of theIndian Law Institute.

[vi] AIR 1961, SC 998

[vii] AIR 19 1959, Mad 239


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