Trending: Call for Papers Volume 4 | Issue 2: International Journal of Advanced Legal Research [ISSN: 2582-7340]



This paper examines the use of insanity as a defense in criminal law, focusing on the Indian legal system. It explores the differences between legal and medical insanity, highlighting that not all mental illnesses are covered by this defense. The historical context is discussed, particularly the famous R. v. Daniel McNaughton case, which created the guiding principles referred to as the ‘M’Naghten Rules.’ The particular standards for the insanity defense are outlined in Section 84 of the Indian Penal Code. Discussion of the burden of proof focuses on the accused’s obligation to establish their mental incapacity and absence of Mens rea. This paper further emphasizes the importance of the defense of insanity in establishing a harmony between justice, compassion, and public safety in its conclusion.

About the Topic

Insanity is often characterized as a severe mental disorder in which a person cannot discern fiction from reality, cannot conduct their affairs owing to psychosis, or exhibits uncontrollable impulsive behavior.[1] The word ‘insanity’ could describe various mental disorders ranging from depression and anxiety to schizophrenia. In criminal law, it is widely accepted in most countries that the inability to commit crimes exempts the individual from punishment.[2]The affirmative defense of legal insanity adheres to the fundamental concept of exonerating offenders with specific mental ailments whose disorder prevents them from logically grasping their actions when committing a crime. However, while discussing the defense of insanity concerning criminal jurisprudence, we need to consider legal insanity rather than medical insanity.

The High Court of Judicature at Madhya Pradesh has effectively outlined the distinction between ‘Legal Insanity’ and ‘Medical Insanity’ in the context of Section 84 of the Indian Penal Code, referred to as the IPC. The bench consisting of Justice G.S. Ahluwalia and Justice R.K. Shrivastava observed the following- “Even insanity is not exempted under Section 84 of IPC. Every person who is mentally ill is not ipso facto exempted from criminal responsibility. There is a distinction between legal insanity and medical insanity. To take benefit of Section 84 of IPC, the accused must prove legal insanity, not medical insanity. Any person suffering from mental weakness is called “medical insanity,” however, “legal insanity” means a person with a mental illness should also have a loss of reasoning power. Furthermore, the legal insanity must be at the time of the incident. In other words, it can be said that to attract legal insanity, a person should be incapable of knowing the nature of the act, or he is doing what is either wrong or contrary to the law. Thus, mere abnormality of mind or compulsive behavior is not sufficient to take benefit of Section 84 of IPC.[3]

The defense of insanity is based on two central legal maxims, which are actus reus non facit reum nisi men’s rea, meaning that an act is not guilty and is not punishable until committed with a guilty mind, and furiousnullavoluntasest,[4]which asserts that individuals with an unsound mind cannot be held legally liable for their actions because they lack the requisite Men’s rea(guilty mind) required to commit a crime. Section 84 of the IPC was formed while considering English common law, specifically the House of Lords’ verdict in the case of R. v. Daniel Mc Naughten[5]. In January 1843, Daniel M’Naghten obtained a revolver and shot Edward Drummond, whom he mistook for British Prime Minister Robert Pell, fatally injuring him. Consequently, Drummond died, and M’Naghten was charged with his murder. He pleaded not guilty because of insanity. At trial, witnesses were called on behalf of the defendant, M’Naghten, to testify that he was not in a sound state of mind at the time of committing the offense. There was medical evidence presented during the trial, which stated that people of otherwise sound mind could be affected by morbid delusions and that M’Naghten was one of them. Further, a person suffering from such delusion may, under normal circumstances, have a moral perspective of what is right and wrong. Still, behaviours related to their fantasy may be executed beyond their comprehension, leaving them with no such perception. As a result, it was decided that M’Naghten could not exert control over his actions while under the influence of his illusion. Because of the nature of M’Naghten’s condition, these illusions progressed gradually until they reached a climax, resulting in Edward Drummond’s death. Evidence submitted before the Court regarding the state from which M’Naghten suffered further revealed that a man might go on for years quietly while under the grip of the delusion while having the capacity to break out into extravagant and violent paroxysms. Subsequently, the defense of insanity was accepted, and Daniel McNaughten was acquitted.[6]Through this case, the propositions popularly known as ‘the M’ Naghten Rules’ were established. The most crucial ones were: First, every man is believed to be of sound mind until proven otherwise. Second, for the defense of insanity to succeed, it must be proven that the accused was under a false belief and did not know the nature of the action he committed, or if he knew the act, then he failed to understand it was wrong.[7]In common law jurisdictions, the M’Naghten rules established a de facto standard test to determine the defendant’s mental state and criminal responsibility. Based on these principles, the IPC provides that a person suffering from a defect of reason caused by a mental condition or ailment will be acquitted of the offense charged if his medical condition produced one or more of three incapacities when the alleged crime occurred. The incapacities are:-

  • The inability to know the type and quality of the act performed;
  • The inability to know that the conduct was incorrect; and
  • The inability to regulate the act’s performance.[8]

Under Section 84 of the IPC, the defense of insanity is provided as follows- “Acts of a person of unsound mind— Nothing is an offense which is done by a person who, at the time of doing it, because of unsoundness of mind, is incapable of knowing the nature of the act or that he is doing what is either wrong or contrary to the law.[9]

Concerning the burden of proof as well as the onus of proof about using the defense of insanity, it was held in  Surendra Mishra V. State of Jharkhand that“In law, the presumption is that every person is sane to the extent that he knows the natural consequences of his act. The burden of proof in the face of Section 105 of the Evidence Act is on the accused. Though the burden is on the accused, he is not required to prove the same beyond all reasonable doubt but merely satisfy the preponderance of probabilities. The onus has to be discharged by producing evidence of the conduct of the accused before the offense, his conduct at the time, or immediately after the offense concerning his medical condition by producing medical evidence and other relevant factors. Even if the accused establishes unsoundness of mind, Section 84 of the Indian Penal Code will not come to its rescue in case it is found that the accused knew that what he was doing was wrong or that it was contrary to the law. To ascertain that, it is imperative to consider the circumstances and the behavior preceding, attending, and following the crime. The behavior of an accused about a desire for concealment of the weapon of offense and conduct to avoid detection of crime go a long way to ascertain whether he knew the consequences of the act done by him.”[10]This means the burden of proof is placed on the accused by the defense, who must demonstrate their mental incompetence and lack of criminal intent. It also considers the accused’s actions before, during, and after the offense.

In conclusion, the defense of insanity is essential to criminal law because it balances the ideals of justice, compassion, and public safety. It recognizes the complex relationship between mental illness and criminal behavior. It aims to ensure that people who are genuinely unable to appreciate the illegality of their actions are treated with appropriate care and assistance rather than punitive measures. It protects the rights of people suffering from severe mental ailments and ultimately contributes to public safety. In essence, the defense of insanity is an essential component within the legal system that promotes fairness and humanity in treating individuals facing criminal charges resulting from their mental illness.

[1] Howes, R. The definition of insanity – Perseverance versus perseveration, Psychology Today. Available at: https://www.psychologytoday.com/intl/blog/in-therapy/200907/the-definition-insanity.

[2] Math, S.B., Kumar, C.N. and Moirangthem, S. Insanity defense: Past, present, and future – sage journals, Sage . Available at: https://journals.sagepub.com/doi/10.4103/0253-7176.168559 .

[3] Tufan V. State of Madhya Pradesh, through Police Station Indar  2022 SCC OnLine MP 1718 : 2022 Cri LJ 3482.

[4]Furiousinullavoluntasest definition Law Insider. Available at: https://www.lawinsider.com/dictionary/furiousi-nulla-voluntas-est.

[5] R v. Daniel Mc Naughten, 1843 RR 59.

[6] Ltd, A.A. (2023) R v McNaughten – M’Naghten, Law Teacher. Available at: https://www.lawteacher.net/cases/r-v-m-naghten.php.

[7] Saikia, D. Insanity defense in criminal law in India, International Journal of Law Management and Humanities. Available at: https://www.ijlmh.com/wp-content/uploads/2019/03/Insanity-Defense-in-Criminal-Law-in-India.pdf.

[8] Yeo, S. RETHINKING THE INCAPACITIES OF INSANITY, Jstor. Available at: https://www.jstor.org/stable/pdf/44013849.pdf?refreqid=fastly-default%3A76b4843fea292e5b518abed38e51d53c&ab_segments=0%2Fbasic_search_gsv2%2Fcontrol&origin=&initiator=search-results&acceptTC=1.

[9] The Indian Penal Code, 1860 – Act No. 45 of 1860

[10] Surendra Mishra v. State of Jharkhand (2011) 3 SCC(Cri.) 232.