Criminal Law- Defence of Unsound Mind- Law and Judgments


October 30, 2018

Section 84 of the Indian Penal Code carves out an exception that an act will not be an offence, if done by a person, who at the time of doing the same, by reason of unsoundness of mind, was incapable of knowing the nature of the act, or what he is doing is either wrong or contrary to law.

Doctrine of burden of proof in the context of the plea of insanity 


The doctrine of burden of proof in the context of the plea of insanity was expounded by the Apex Court in the case of Dahyabhai  Chhaganbhai  Thakkar   v. State of Gujarat [1], wherein the Court stated that:

  1. The prosecution must prove beyond reasonable doubt that the accused had committed the offence with   the   requisite   mens   rea,   and   the   burden   of proving that always rests on the prosecution from the beginning to the end of the trial.
  2. There   is   a   rebuttable   presumption   that   the accused was not insane, when he committed the crime, in the sense laid down by Section 84 of the IPC: the accused may rebut it by placing before the Court all the relevant evidence- oral, documentary or circumstantial, but the burden of proof upon him is no higher than that rests upon a party to civil proceedings.
  • Even  if  the  accused  was  not  able  to   establish conclusively that he was insane at the time he committed the offence, the evidence placed before the Court by the accused or by the prosecution may raise a reasonable doubt in the mind of the Court as regards one or more of the ingredients of the offence, the evidence placed before the Court by the accused or by the prosecution may raise a reasonable doubt in the mind of the Court as regards one or more of the ingredients of the offence, including mens rea of the accused and in that case the Court would be entitled to acquit the accused on the ground that the general burden of proof resting on the prosecution was not discharged.

Burden of Proof on the Accused to prove Insanity

In the case of Surendra Mishra vs.  State of Jharkhand[2], the Supreme Court noted that the accused in such cases has to only establish his defence on a preponderance of probability after which the onus shall shift on the prosecution to establish the inapplicability of the exception.

Standard test is of Legal Sanity and not Medical Sanity

In the case of State of Rajasthan vs. Shera Ram[3], the Court was of the view that the standard of test to be applied shall be of legal insanity and not medical insanity. The Court observed that once a person is found to be suffering from mental disorder or mental deficiency, which takes within its ambit hallucinations, dementia, loss of memory and self-control, at all relevant times by way of appropriate documentary and oral evidence, the person concerned would be entitled to seek resort to the general exceptions from criminal liability.

Crucial point of time at which unsoundness of mind should be established

In the case of Ratan Lal vs. State of Madhya Pradesh[4], the Supreme Court held that the crucial point for considering the defence of plea of unsoundness of mind has to be with regard to the mental state of the accused at the time the offence was committed collated from evidence of conduct which preceded, attended and followed the crime.

An essential observation in the aforesaid context was also made by the Supreme Court in the case of Vijayee Singh vs. State of U.P.[5], whereby the Court observed that if from the materials placed on record a reasonable doubt is created in the mind of the Court with regard to the mental condition of the accused at the time of the occurrence of crime, he shall be entitled to the benefit of the reasonable doubt and consequent acquittal.

Also read Supreme Court’s recent verdict on Burden of Proof in case of Plea of Insanity here.


[1] (1964) 7 SCR 361

[2] (2011) 11 SCC 8

[3] (2012) 1 SCC 602

[4] (1970) 3 SCC 533

[5] (1990) 3 SCC 190