A person who is mentally ill is considered incapable of having the requisite mens rea to commit a crime, so mental illness provides a complete defense against any criminal prosecution. A person with mental impairment who commits a crime is released from criminal accountability under Section 84 of the Indian Penal Code, 1860.

Until the opposite is demonstrated, the established legal position is that every individual is assumed to be sane and to possess a sufficient degree of reason to be liable for his act. If the accused wants to take use of this exemption under section 105 of the Indian Evidence Act, 1872, they have the burden of proving that their mental state was as indicated by section 84 at the critical moment.

The defense must demonstrate that the offender was so mentally ill at the time of the offense that he was unable to understand the nature of the deed he was doing. The accused only needs to use the preponderance of the evidence to probabilistically support his case.

Rationale behind Exemption
A mentally sick person is incapable of exercising self-control or self-discipline. These people cannot be held legally accountable for their behavior because they lack the mental capacity to comprehend the consequences of their actions or to appropriately judge their own actions. When such people are punished, punishment is meaningless since they are unable to comprehend why they are being punished or that they are being punished at all.

The defense provided by Section 84 of the Code is predicated on the idea that an act must be undertaken with "guilty" intention in order for it to be considered criminal, and that an act may be committed even if the person who committed it was unaware of its nature, its wrongfulness, or its illegality.

Unsoundness of mind
A noncompos mentis, or "not of sound mind," is someone who suffers from mental illness. A composed mind is known as compose mentis. Non compos mentis refers to the inability to maintain mental equilibrium or control. A person's mental state might be unstable due to several factors such as extreme alcohol or drug addiction, natural or imposed illness, birth or disease (schizophrenics, for example), or permanent (idiocy).

Unsoundness to exist at the time of the commission of the Offence
Every time a legal insanity plea is established, the court must decide whether or not the accused was mentally ill when the offense was committed. The material time when the offense is committed is critical for determining the accused's mental state. In the case of Amrit Bhushan Gupta v. Union of India, it was decided that the accused could not be freed from responsibility for the offense, even if the court determined that he was insane at the time the offense was committed, regardless of whether the insane state occurred earlier or later.

Section 84 is applicable if it is discovered that the accused was suffering from a mental impairment at that pivotal moment that prevented him from understanding the nature of the act he was performing, or even if he did, he was unaware that it was illegal or immoral.

The circumstances that before, attended, and followed the offense must be used to determine the accused's mental condition in order for them to be eligible for protection under Section 84 of the Indian Penal Code. The defense must demonstrate that the accused was not acting in a sound mind when the offense was committed.

Incapability in the Accused Person to know
The phrase "incapable of knowing" makes it clear that the burden of proof is with the accused to demonstrate that his mental illness prevented him from understanding the consequences of his acts. What a person knows and what they are capable of knowing are two very different things.


It doesn't matter if he was aware of the nature of his activities; what is protected by Section 84 is an organic or inherent incapacity, not a false belief that could have been the product of distorted potentiality. This incapacity could result from a sudden episode of insanity or delusion, a halted mental development, or another medically recognized cause.

The Court noted in the Lakshmi v. State decision that "a person might believe so many things." His convictions won't be able to keep him safe once it is discovered that he is capable of discriminating between right and wrong. He assumes the risk that the law will hold him accountable for the action that came from him if his potentialities cause him to come to the incorrect decision.

What the law guards against is the situation where a man loses all sense of morality and is unable to discriminate between what is legal and what is not. Where such light is found to be still flickering, a man cannot be heard to plead that he should be protected because he was misled by his own misguided intuition or by any fancied delusion which had been haunting him and which he mistook to be a reality.

Our beliefs are primarily the off springs of the faculty of intuition. On the other hand the content of our knowledge and our realization of its nature is born out of the faculties of cognition and reason. If cognition and reason are found to be still alive and gleaming, it will not avail a man to say that at the crucial moment he had been befogged by an overhanging cloud of intuition which had been casting its deep and dark shadows over them."

Knowledge of nature of the Act
The term "nature of the act" describes the act's physical characteristics rather than its moral nature. It deals with circumstances where the actor is acting without realizing what he is physically doing. For instance, someone who punches someone and believes, out of a delusional state, that he is shattering a jar, or someone who slices another person's finger while slicing a vegetable. The accused in these two cases is unaware of the nature of his actions.

In the case of Chirangi v. State, the 45-year-old widower accused, Chirangi Lohar, was found guilty of using an axe to murder his 12-year-old son while they were visiting Budra Meta on a hilltop. Lohar was a dedicated father to his son. He argued in defense that he killed his son because he thought the boy was a tiger that was going to attack.

According to medical testimony, Chirangi could have mistaken his son for a tiger because of his bilateral cataract, a condition that he had before the relevant date. There was an abscess in his leg could have produced a temperature which might well have been responsible after the fall for a temporary delirium which might have created a secondary delusion to magnify the image created by the defect in vision.

Chirangi suffered from cardio-vascular disease which would have resulted in temporary confusion, and the injury to his eyebrow could have caused a state of concussion during which he might have inflicted the injuries on his son without being conscious of his actions. All this showed clearly enough that Chirangi's fall combined with his existing physical ailments could have produced a state of mind in which he in good faith thought that the object of his attack was a tiger and was not his son.

Written By: Akanksha