Wednesday, 26 January 2022

When Can Insanity Act As A General Defence Under I.P.C

 When Can Insanity Act As A General Defence Under I.P.C

By Nemi Bhavsar

What is meant by insanity?

Oxford Dictionary defines it as a state of madness or acting in a foolish and dangerous way. In the field of law it is that condition of mind where an individual is unable to judge the natural consequences of his/her act or to act rationally.

Insanity is categorised under two heads:

  • Insanity by Birth,

  • Insanity developed after birth.

In general, we come to know about delusion, somnambulism i.e. walking while sleeping, epileptic attacks, depression, extreme anger as some kind of mental disorders.

Which kind of insanity is protected under I.P.C?

Not all kinds of mental disorders are protected under I.P.C. Every minor mental aberration is not insanity.[i] I.P.C gives protection to one who at the time of committing an offence was mentally ill to such an extent that he lost his reasoning power to understand the nature of his act or it being contrary to law. Here the nature of the act means it's reasonable and normal consequences.

What is the difference between legal insanity and medical insanity?

Legal insanity indicates a situation when a person completely loses his soundness of mind; his decision making abilities and gets reliant on others. Whereas under medical insanity, a person is under medication or treatment from a psychiatrist but is capable of making decisions.Legal insanity is concerned with conduct of the person at the time of commission of the crime. On the other hand, medical insanity analyses a patient's overall conduct in past and present and observes him in the future.Thus under legal insanity a person loses his juristic identity and creates incapacity i.e. releases him from criminal liability. While in medical insanity he doesn't loses his recognition under law.

Why is unsoundness of mind a defence under I.P.C?

Actus Reus Non Facit Reum Nisi Mens Sit Rea i.e. an act forbidden by law (penal law) is not punishable if it is not accompanied by a guilty mind. Thus with the help of this maxim it can be justified that unsoundness of mind needs to be protected as an insane person is incapable of forming the required guilty mental element.

This complete defence is further based on two maxims, i.e.

  • Furiosus Absentis Low Est meaning a mad man has no will and

  • Furiosus Furore Sui Puniter meaning a mad man is punished by his own madness.

Essentials of Section 84 of I.P.C

As per Section 84 of I.P.C the essentials for availing this defence are:

  • Unsoundness of mind at the time of commission of the offence.


  • Incapable of knowing the nature of the act; or that the act was contrary to law; or that the act was wrong.


  • Unsoundness of mind as contemplated under Section 84 of I.P.C is legal insanity which requires that cognitive facilities of the accused are such that he does not know or what he has done or what will follow from his act. [ii]


  • Unsoundness of mind prior or after the commission of the crime can't absolve the offender under this section. It is crucial for the accused to establish that he possessed an unsound mind at the time of committing the offence. Thus if a person commits an offence during lucid interval i.e. a period when he is mentally sane; then he can't get exempted from his criminal liability. [iii]


  • When an individual during the performance of an act is ignorant of its physical characters; it can be said that he was incapable of knowing the nature of the act. Further, if one is aware of the nature of the act but not that it is contrary to law or wrong then he gets pardoned.


  • The word wrong under this section stands for moral wrong and not legal wrong.

Important case laws on insanity as a defence

M'Naghten case

The foundation for the law of insanity was laid down by the House of Lords in 1843 in this very case. The accused by the name of Daniel M Naghten suffered from a delusion that Sir Robert Peel, the then Prime Minister of Britain had injured him. He mistook Edward Drummond. Secretary to the Prime Minister for Sir Robert Peel He shot and killed him. The accused took the plea of insanity. The medical evidence showed that M Naghten was labouring under a morbid delusion which carried him away beyond the power of his own control. He was acquitted and the House of Lords laid down certain principles which are popularly known as M'Naghten Rules.

Oyami Ayatu v/s State of Madhya Pradesh

The accused was a life convict and the deceased was his co-prisoner. The deceased went to the urinal in the night, where he slipped due to the bamboo sticks which had been spread by the accused in a shed. The accused attacked the deceased with a knife and killed him. The fact that the accused made a clean breast of his crime didn't prove his unsoundness of mind. Further, the Court held that the fact that the accused caused the death over a trivial matter is not by itself a proof of insanity. The death sentence was confirmed.

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