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Updated: Dec 1, 2020

By Mahima Mishra, V year B..B.A., LL.B. Vivekananda Institute of Professional Studies, Contact no: 9315322789, E-mail:

The idea of defence by insanity has existed since ancient Greece and Rome. The main referred to the acknowledgement of insanity as a barrier to criminal allegations was recorded in 1581. English legitimate composition expressing that, "If a crazy person or a characteristic imbecile, or an insane person in the hour of his lunacy" kills somebody, they can't be considered responsible. In Indian Legal System "Insanity Defence" is an instrument in criminal law to spare a claim from the responsibility of wrongdoing. It depends on the presumption that at the hour of the crime, the individual was experiencing psychological maladjustment and in this manner, was unequipped for understanding what he/she was doing. This article deals with the concept of Insanity and also analyzes various tests which are formulated from time to time. This article also briefly discusses the misuse of the defence of insanity.

Keywords: Insanity, defence, offence, unsound mind, test


The Indian Penal Code, 1860 identifies defences in chapter four below the title ‘General Exceptions.’ Sections 76 to 106 of the IPC include these defences. The law allows certain defences that excuse criminal liability. These defences are based on the principle that though the person committed the offence, he cannot be held liable. This is because, at the moment of the commission of the offence, either the prevailing circumstances were such that the act of the person was justified or his state was such that he could not form the necessary mens rea for the crime.

The unsoundness of mind should be of such an extent that it makes the offender incompetent in understanding the nature of the act. The constituent that the person is suffering from a mental illness is by itself not adequate to prove that he is insane. Under Indian law, the rationale of insanity as a defence is included in Section 84 of the Indian Penal Code, 1860, and is based upon the “McNaughton's Rule.” The burden of proof is always on the defendant, and it has to be proved beyond a reasonable doubt. The Law Commission of India in its 42nd report attempted to reanalyze Section 84, but no changes were done.


The insanity law as a defence has been in presence for various centuries. But, it gained a legal standing from the last three centuries. The history of the law of insanity can be followed back to the 1700s.

The first case which discussed the law of insanity was R v. Arnold (1724), in which Edward Arnold tried to kill and even wound Lord Onslow and was adjudicated for the same. The evidence simply revealed that the accused was suffering from a mental disorder. Tracy, J. observed:-

“If he was under the visitation of God and could not distinguish between good and evil, and did not know what he did, though he committed the greatest offence, yet he could not be guilty of any offence against any law whatsoever.”

As asserted in the aforementioned case, a person can take immunity if, due to his unsoundness of mind, he was incompetent of differentiating between good and evil and did not know the nature of the act perpetrated by him. This test is known as the “Wild Beast Test.” The second test was developed in Hadfield's case (1800). Hadfield was removed from the army on the ground of insanity and was tried for high treason in trying to assassinate King George III. The attorney of the accused, Lord Thomas Erskine, defended him and proved in presence of the judge that Hadfield only pretended to kill the King and is not guilty, on the ground of insane delusion from which the accused was suffering.

Erskine pronounced that insanity was to be defined by the fact of fixed insane delusion and that such delusion under which the defendant acted is the main reason for his crime. This test was known as the “Insane Delusion Test.”

Finally, the third test was expressed in Bowler’s case (1812). In this case, Le Blanc, J. affirmed that the jury has to determine when the accused committed the offence, whether he was competent in identifying right from wrong or under the control of an illusion. After the Bowler's case, the courts have placed more stress on the capacity of the accused to distinguish right from wrong, though the test was not that clear.

Insanity under Indian Law:

Under Indian law, Section 84 of the Indian Penal Code, 1860, the defence of insanity is provided and is based upon the “McNaughton's Rule.” Though the section does not explicitly mention the word “Insanity,” it talks about unsoundness of mind. It clearly states that an act committed by a person, cannot be termed as an offence if he is incapable of understanding the nature of the act, or that he is doing something wrong.

For taking section 84 as a defence, the following elements need to be established:

1. The Act must be committed by a person of unsound mind.

2. Such a person should have no understanding of:

i. The nature of the act, or

ii. That the act was wrong, or

iii. That the act was against the law.

Such inability should exist only because of unsoundness of mind of the accused.

The incapacity must be there at the time of the commission of the act.

There are four different categories of persons who are said to be incapable of knowing the nature of the act, or are not of sound mind (non-compos mentis):

1. An idiot

2. A lunatic

3. A Mentally-ill person

4. An intoxicated person

Legal Insanity v. Medical Insanity:

Broadly, Medical insanity and Legal insanity are two types of insanity. Medical insanity is a broad concept; it includes all the persons who are suffering from a mental disorder and is solely dependent upon medical grounds. But this is not the case with legal insanity, here, the essential factors are those which are important to be proved in a court of law, based on which the accused can be released.

For establishing legal insanity, one has to prove the necessary factors provided under section 84 of the Indian Penal Code. It would not be wrong to say that every legal insanity is medical insanity, but every medical insanity might not be legal insanity. A person might be certified insane or sane, medically, but legally he will be considered as insane only when he proves the components of section 84 of Indian Penal Code. If the person fails to establish that he was legally insane at the time of the commission of the act, then he will not be acquitted, even if he was medically insane at that time.

Judicial Response:

In Kamala Bhuniya v. State of West Bengal, the blamed was pursued her husband’s murder with an axe. A suit was documented against the accused; she asserted to be crazy at the hour of the incident, the researching official recorded at the underlying stage about the charge’s psychological craziness. The arraignment's obligation was to orchestrate the charge’s clinical assessment; it was held that there was no thought process in murder. The charge made no endeavour to escape, nor made any endeavour to evacuate the implicating weapon, was Failure with respect to the prosecution to release his underlying obligation regarding the nearness of mens rea in the blame at the ideal opportunity for the commission of the offence. The accused was entitled to the advantage of Section 84. What's more, subsequently accused was held to be crazy at the hour of the commission of the offence and was held guilty of Culpable Homicide and not of Murder.

In Bapu @ Gajraj Singh v. State of Rajasthan, Hon'ble Supreme Court held that Mere variation from the norm of the brain or partial delusion, overpowering impulse or impulsive conduct of a mental case manages no protection under Section 84 IPC.

A fundamental perception made by the Supreme Court on account of Vijayee Singh v. State of U.P, whereby the Court saw that if from the materials set on record, a sensible uncertainty is made in the mind of the Court concerning the state of mind of the blamed at the ideal opportunity for the event of a crime, he will be entitled to serve the sensible uncertainty and ensuing acquittal.

Abuse of Insanity as a Defence:

In the current situation, there are great possibilities that the defence of insanity can be very well abused as it is a very strong weapon to evade the charges of an offence. It is difficult to prove that the person was incapable of appreciating the nature of the act. Defence lawyers can use it to release the culprits of intentional unlawful acts.

Here the courts play an important rule as they have to make sure that a sane person doesn’t absolve himself by wrongfully using the defence in his favour. In many jurisdictions, this defence has been abolished completely, e.g., Germany, Thailand, Argentina, etc.


The Law of insanity is of reasonable importance as it helps in recognizing the situation and the mental position of an insane person. The defence of insanity is thoroughly criticized, because, under this defence, the court is not required to examine whether the offence has been committed or not, but has to ascertain the intention of the accused which is difficult. Even the term “insanity” should be properly defined to avoid any difficulty in understanding, who all will be entitled to get protection under this defence.

Proper demarcation should be done between brutal criminals and insane criminals. Section 84, IPC cannot be invoked except if it is proved that the accused was suffering from legal insanity. Mental insanity can be proved, but in the end, it is upon the discretion of the judges to decide whether the person will fall within the ambit of section 84, IPC.

1 comment

1 Comment

Aug 25, 2020

Nice article👏👏👏

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