• Legis Scriptor

Medical Insanity vs. Legal Insanity

Authored by - Divyanshi Pathak

Keywords - Unsound Mind, Defence, Legal Insanity, Medical insanity


The defence of insanity is based on the very well-established principle “Actus Non-Facit Reum Nisi Mens Sit Rea", which in literal sense means that there should be an intention and guilty mind of the accused to charge them with a criminal offence. The article talks about the difference between legal insanity and medical insanity with the help of relevant provisions of the law along with case jurisprudence.


All of us know that a guilty mind is an essential element, in order to, be convicted for committing a crime. The long-standing principle of 'men's rea' is a requirement in criminal offences. Since the offender ought to have a guilty mind, subsequently, a person of unsound mind cannot commit a criminal offence. The accused should have an unsound mind to an extent that they do not know the nature of the act committed by them. Section 84 under the Indian Penal Code talks about insanity which is based upon the “Mc’Naughten’s Rule”.

Medical Insanity vs. Legal Insanity

Section 84 IPC, states that “Act of a person of an unsound mind: Nothing is an offence which is done by a person who at the time of doing it by reason of unsound mind is incapable of knowing the nature of the act or that he is doing what is either wrong or contrary to law”. This Section of IPC was analysed again under the 42nd report of law commission of India but no substantial changes were made. There have been a lot of tests that have been formulated from time to time but Mc’Naughten’s Rule has played a significant role in determining unsoundness.

Mc'Naughten's Rule started the right and wrong test. The principles cited under this rule are:

- Any act is punishable if the person doing that act knew what he was doing or was under the partial delusion.

- It is always assumed that every man is prudent or sane and has knowledge of what he is doing

- To use the defence of insanity it has to prove that at the time of doing an act the accused was in such a state of mind that he was unable to know the nature of the act committed by him.

- A person who has sufficient medical knowledge and is familiar with the disease of insanity cannot be asked to give his opinion because it is for the Jury to determine and decide accordingly.

- Under IPC Section 84 the term referred to is mental unsoundness and not insanity. The defence of mental insanity comes from the McNaughten rule. According to this Section, a person of unsound mind will have no understanding of his actions and does not know what is wrong or contrary to legislation, due to lack of a sound mind.

There are two essential that has been established under Section 84 of IPC. First being the queues was in a state of unsoundness of mind at the time of the commission of the act and second being, he was unable to know the nature of the act for what was either wrong or contrary to law. If both these essential requirements are met, the defence of insanity can be proved and used in Court.

Also, the law regarding insanity has been discussed in the recent judgement of the supreme Court in the case of Surendra Mishra vs the State of Jharkhand[1]. The High Court held that the accused has to prove legal insanity and not medical insanity. Every person suffering from the mental disease is not exempted from criminal liability. The accused has to prove legal insanity beyond all reasonable doubt and the burden of proof is always on the defendant.

Section 84 of IPC distinguishes legal responsibility from the medical test. It has to be noted that the absence of will not only arises from the absence of understanding but also from an abnormal state of mind.

According to the legal point of view, a person has to be held responsible when he does not know to distinguish between right or wrong. In practice, not every person who is medically ill is exempted from criminal liability. It has been said by the Supreme Court that such people are unable to seek immunity from a criminal case as it is their responsibility to demonstrate insanity at the time of the commission of the crime.

In the case of Hari Singh Gond vs state of Madhya Pradesh[2], the Supreme Court observed that there is a legal test laid out by Section 84 in case of medical Insanity. A distinction must be made between legal insanity and medical insanity. The Court is concerned with the legality of an insane person, not medical insanity.

Time and again, Court has specified that unsoundness of mind must be at the time of the commission of an act. In the case of Ratan Lal vs the state of MP[3], the Court held that the unsound mind should be established when the crime is committed and whether the accused was in such a state of mind as to be entitled to benefit from Section 84.

Incapacity to know the nature of the act and inability to know between right or wrong are the two circumstances considered while deciding such cases. The basic difference between medical insanity and legal insanity is that medical insanity deals with the person’s overall conduct in the past and future, whereas legal insanity deals with the unsound conduct of an accused during the commission of the offence. Not every accused, who has medical insanity would be considered under the ambit of legal insanity.

In the present scenario, there are high chances that defence of insanity can be misused, by defence lawyers to free the culprits, from being punished for unlawful activities. The Judiciary plays a very important role to make sure that a sane person does not take the defence. In regards to Section 84, the term medical insanity and its scope should also be defined in a more comprehensive manner by the Courts.


[1] 2005 (4) JCR 439 Jhr [2] MANU/SC/3700/2008 Hari Singh Gond vs. State of M.P. (29.08.2008 - SC) : MANU/SC/3700/2008 [3] MANU/MP/0573/1999 Manjulata vs. State of M.P. and Ors. (22.12.1999 - MPHC) : MANU/MP/0573/1999

[4] Indian Penal Code, 1860

[5] https://blog.ipy-defence-indian-penal-code/,