Plea of Insanity – Can you get away with Murder?

Plea of Insanity - Section 82 IPC

Why should you read this?

Let me ask you an interesting question.

Should an insane person be punished if he commits a murder?

Some of you would say, “yes”. After all, a crime is a crime and someone lost their life.

Some of you would say, “no”. After all, the murderer didn’t know what he was doing.

In this post, let’s dive deep into this complex layered question and peel off some layers of mystery around this.

Table of Contents

  1. What is Plea of Insanity?
  2. McNaughton Story & Plea of Insanity
  3. Indian Courts & statistics on success of plea of Insanity
  4. Factors affecting the verdict in case of Insanity defence
  5. Factors to keep in mind while taking plea of Insanity
  6. Presenting Evidence with Plea of Insanity
  7. Mental Health in India – Statistics
  8. Conclusion

What is Plea of Insanity?

So, we started out by asking a question. And here is what the Indian law says about it.

Section 84 of Indian Penal Code, 1860 (IPC) states that anything done by a person of unsound mind is not an offence if at the time of committing the offence, he was

  1. not capable of knowing the nature of his act; or
  2. that his act is wrong; or
  3. it is contrary to law

Simply put, a person who is mentally unsound or insane and who doesn’t understand that he is doing an illegal act when he does it, cannot be held liable for the act done and, hence, cannot be punished.

As we all know, there are two components to every crime – “actus reus” i.e. the act which constitutes the crime itself and “mens rea” which means a guilty mind.

There can be no criminal offence without both these components being present.

What this means is that if a person without an intention to commit a crime or without knowing or understanding that he is committing a crime, does an act which may by itself be considered a crime, then he cannot be held guilty or punished for it.

Ex. 1 While hunting deer in the forest (where doing so is permitted by law), a person accidentally shoots another person and kills him. In this case, he clearly did not intend to kill the victim. Hence, he will not be held guilty of murder.

Ex. 2 A person suffering from schizophrenia, in a violent episode of paranoia, hits another person on the head with a stick and kills him. Here, the killer, suffering from mental illness, i.e. schizophrenia, does not understand that he is committing a crime and the implications of his actions.

As we saw in both the examples, the component of a guilty mind or an intention to commit a crime is absent. Hence, in these cases, the person committing these acts cannot be punished for committing the crime.

The second example above is a classic example of the insanity defence where it satisfies both the criteria, i.e., the person suffers from a mental illness or is mentally unsound and commits an act where he is incapable of understanding the nature of his act or that his act is illegal and wrong.

McNaughton Story & Plea of Insanity

They say truth is often stranger than fiction. The story I’m about to tell will surely convince you on this.

In 1843, an Englishman named Daniel McNaughton shot and killed Edward Drummond.

Edward Drummond was the Secretary to the then British Prime Minister, Sir Robert Peel.

McNaughton, since a long time before he killed Edward, had been under the delusion that he was being persecuted by the Tories (The Conservative Party in the UK, colloquially called the Tories) and that they were about to kill him.

So, when he saw Edward Drummond leaving the residence of Sir Robert Peel, he followed him and shot him!

During his interrogation after the arrest he said,

“The Tories in my native city have compelled me to do this. They followed me to France, into Scotland and all over to England. In fact, they follow me wherever I go… They have accused me of crimes of which I am not guilty; they do everything in their power to harass and persecute me. In fact, they wish to murder me.”

Two years before the murder, McNaughton had even complained to the Police Commissioner to help stop his alleged persecution and harassment.

Initially, he was charged for wilful murder.

But when his case came up in appeal, several doctors testified about McNaughton’s mental illness. He was then acquitted of murder and forcefully sent to the hospital where he stayed for 20 years and then a mental asylum till his death.

Later, during a discussion in the House of Lords, the Lord Chancellor put five questions to the panel of His Majesty’s Judges. The 5 Questions were replied on 19th June 1843, and they were construed as McNaughton’s rules. The following are the main points of McNaughton’s rules:

1. Every man is to be presumed to be sane and to possess a sufficient degree of reason to be responsible for his crimes, until the contrary be proved.

2. An insane person is punishable “if he knows that his actions are wrong or illegal” at the time of crime.

3. To establish a defence on insanity, the accused, by defect of reason or disease of mind, is not in a position to know the nature and consequences.

4. The insane person must be considered in the same situation as to responsibility as if the facts with respect to which the delusion exists were real. Simply put, the criminal liability of the insane person must be computed as if the delusion under which he committed the crime was real and not imagined.

5. It was the jury’s role to decide whether the defendant was insane.[1]

Did you know that Section 84 IPC has been derived from these McNaughton’s rules?

Indian Courts and statistics on success of plea of Insanity

A study[2] published in the Indian Journal of Psychological Medicine estimated the success rate of insanity pleas in Indian High Courts and the factors affecting the outcome of such insanity pleas.

The researchers studied 102 cases from 13 High Courts of judgements delivered over a decade between 2007 and 2017, all of them being appeals either against conviction or acquittal by lower courts.

The findings were interesting.

Out of the 102 cases examined, the High Court convicted the accused in 76 cases (74.50%), thereby rejecting the insanity defence. The High Court acquitted the accused under section 84 IPC in 18 cases (17.65%). The success rate of the insanity defence plea was thus around 17% in the studied cases.

In 78 out of 102 cases (76.50%), the crime in which an insanity plea was raised was murder. This makes the defence critical as the difference between acquittal and conviction can be a life sentence to the accused.

The most common diagnosis provided by the psychiatrist, as an expert witness was schizophrenia and other psychotic disorders.

Factors affecting verdict in case of Insanity defence

It was also found that those who were convicted by the lower court had a much higher probability of getting convicted by the High Court, and conversely, those who were acquitted by the lower court due to insanity had a much higher probability of getting acquitted due to insanity by the High Court.

Those cases where there was a document to prove that the person was mentally ill prior to the crime had a higher probability of being acquitted due to insanity by the High Court.

In those cases where the psychiatrist’s opinion was not obtained (in about 24 cases), or the psychiatrist reported that there was no mental illness in the accused (six cases), there was no verdict of acquittal under Section 84 of IPC.

Thus, it is quite clear that Indian Courts mostly reject the defence of insanity and weightage is attached to documentary evidence of the presence of such illness by psychiatrists.

Factors to keep in mind while taking plea of Insanity

The following are the most important things to remember if you or anyone you know has to take the insanity defence plea.

  1. Every person who is suffering from mental disease is not ipso facto (by the fact itself) exempted from criminal liability.[3]
  2. A distinction has to be made between medical insanity and legal insanity. A court is concerned with legal insanity, and not with medical insanity.[4]
  3. There is no standard procedure to establish insanity defence.
  4. The totality of the circumstances is seen. The unsoundness of mind before and after the incident is a relevant fact.[5]
  5. In Bapu @ Gajraj Singh V. State of Rajasthan[6], the Supreme Court laid down which illnesses qualify for this defence and which don’t. It said that mere odd, conceited or irascible behaviour or any illness which weakens the intellect or affects one’s emotions or will does not qualify for this defence. Also, if the accused has recurring fits of insanity or epilepsy but his behaviour was normal, that also isn’t sufficient.
  6. Courts attach importance to documentary evidence of previous record of existing mental illness of the accused although this is not the only important thing .
  7. The most important factor is to establish that
    1. the accused was experiencing an episode of the illness during the commission of the crime and
    2. that episode must have led to incapacity to understand that his/her acts are illegal and wrong.
  8. The prosecution must prove beyond reasonable doubt that the accused had committed the offence with the requisite, mens rea; the burden of proof of insanity is on the defendant.

Although the proof may not be conclusive but should create reasonable doubt in the mind of the court as regards one or more of the ingredients of the offence, including mens rea.[7]

  1. It is very important to get a testimony from a professional psychiatrist about the accused’s mental illness.
  2. The burden of proof upon the accused is no higher than that rests upon a party to civil proceedings.[8]

Presenting Evidence with plea of Insanity

Section. 84 of the IPC comes under the general exceptions. Section. 105 of the Evidence Act, 1872 states that where the case of the accused comes within such general exceptions, the burden of proving that the case falls within such an exception is on the accused.

In such cases, the Court presumes the absence of such circumstances. Hence, it is extremely important to present convincing evidence of circumstances supporting the insanity defence. This includes direct evidence by eyewitnesses and original documents relating to medical reports, etc. Expert witnesses of professional psychiatrists also assume tremendous importance in Section. 84 cases.

Hence, the person or counsel pleading defence under insanity must be very careful while presenting evidence of such insanity.

The important tests are:

  1. Was the person going through an episode of insanity DURING the commission of the crime?
  2. Did this episode render him incapable of understanding that his act is wrong and illegal?

This is the essence of the McNaughton Test which has been embodied in Sec. 84 of the IPC.

Mental Health in India – Statistics

The National Mental Health Survey of India, 2015-16 conducted by the National Institute of Mental Health and Neuro Sciences, Bengaluru brought the serious condition of mental health problems in India into light.

The survey covered almost 35000 respondents from various parts and strata of the country.

The survey showed that nearly 15% of Indian adults (those above 18 years) are in need of active interventions for one or more mental health issues.

0.8% of the population is currently suffering from serious mental disorders like schizophrenia, other non-affective psychoses and bipolar affective disorder.

Several other shocking revelations are made about the state of mental health of India as a nation.

This has serious implications for our personal and social health and harmony, crime rates, law and order, etc.


As we saw, the law looks dispassionately and objectively (as it should) at persons affected by serious mental illnesses through the prism of statutes, established processes and evidence, a psychologist will argue for a more compassionate approach in dealing with such persons.

It is imperative to erase the stigma around mental health issues and to create a supportive collaborative and inclusive environment to help these individuals recover from them.

This should include rehabilitation procedures developed in consultation with qualified professionals for mentally ill persons, irrespective of whether they are acquitted or found guilty of a crime, special provisions in the public health infrastructure for mental illnesses and bring it out of the current flawed mental asylum centred system.

Most of all, can we as a society start looking at these persons as victims of mental illnesses rather than criminals or “crazies”.

That is probably the only lasting solution to this problem. And a humane one too.

Comment and let us know what you think about this post.

You can also write to us at, if you want us to write on an unexplored legal topic.

  1. T.V. Asokan, Daniel McNaughton (1813-1865), National Center for Biotechnology Information, (June 16, 08.03AM)
  2. Parthasarathy Ramamurthy, Vijay Chathoth, and Pradeep Thilakan, How does India Decide Insanity Pleas? A Review of High Court Judgments in the Past Decade, National Center for Biotechnology Information, (June 16, 08.47AM),
  3. (2011) 11 SCC 495.
  4. 2008 (4) Cri. 236 (SC).
  5. (2002) 7 SCC 748.
  6. (2007) 3 SCC Cri. 509.
  7. (1964) 7 SCR 361.
  8. (2010) 10 SCC 582.

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