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This article is written by Varchaswa Dubey, from JECRC University, Jaipur. This article is an exhaustive work reflecting the in-depth study of the defense of insanity. Furthermore, the article also reflects various other factors concerning insanity and why there is a need for reform in the laws of insanity. 


It is an established criminal law jurisprudence that a person committing an offence has guilty intentions to commit such crimes and in furtherance, the person must also do some acts with such intention. However, it is practically impossible for an insane person to determine if his/her acts would constitute a crime or that such acts will take away the life of another person and therefore such person lacks requisite mens rea and cannot be held liable for his/her acts. 

The word insanity has not been mentioned anywhere in the Indian Penal Code, 1860 (IPC). However, Section 84 of IPC reserves the term ‘unsoundness of mind’ and states that nothing is an offence which is done by a person who, while doing such acts, is incapable of determining the nature of such acts due to unsoundness of mind. 

The defence under Section 84 is established on the jurisprudence that a person who cannot understand what he/she is doing or what are the consequences of committed acts, shall not attract the punitive measures of IPC. The plea of insanity can also be understood by the Latin maxim, “Actus Non Facit Reum Nisi Mens Sit Rea” which means “an act does not make anyone guilty unless there is a criminal intent or a guilty mind” and “Furiosi nulla voluntas est” which means a madman has no will. 

Insanity is often considered a mental disorder, however, the Indian judiciary is not concerned with medical insanity but legal insanity. Legal insanity differs from medical insanity, thus causing a debate among legal professions and medical professionals. 

The essentials of insanity are mentioned in different cases and in each case, courts apply the same test to determine the unsoundness of mind of the accused. The test applied is the M’Naghten Rule

Origins of insanity 

The origins of insanity as a defence can be traced back to the early establishments of government where they recognized that it is unjustified to punish a person of unsound mind. The first recorded source of insanity as a defence can be traced back to Hammurabi’s code which dates back to around 1772 BC. 

The Romans also practiced the defence of insanity where they found people non-compos mentis (without mastery of mind), and people were not held responsible for their criminal actions and this evolved concept is found in contemporary times as the principle of ‘mens rea’.

Initially, the good and evil test first appeared in the year 1313, on the beliefs of biblical and religious concepts. 

Historical tests laid down 

Certain tests laid down to determine insanity are:

  1. Good and evil test: The first test to determine insanity as a defence was laid down in the good and evil test, which was based on the beliefs of the Bible and religion. The test first appeared in 1313 in a case that was concerned with the capacity of a child below the age of 7. The test held that like children below the age of 7 are incapable of knowing the nature of their act, the insane person was thought of as a child who is not capable of knowing the nature of the act or cannot distinguish “good from the evil”. The good and evil test was used from the 14th Century to the 16th century, but it was later abandoned. 
  2. The Wild beast test: First appeared in the case of Rex v. Arnold, 1724, where the accused was tried for shooting at Lord Onslow because Lord Onslow bewitched him. The relatives of the accused also testified that he was suffering from delusions. The court ruled that the defendant shall be acquitted due to his suffering from insanity and that he did not know what he was doing in a similar way like a “wild beast”. The test continued to apply for a century. 
  3. The right and wrong test: The actual predecessor of the M’Naghten rule is the right and wrong test which originated in the case of Regina v. Oxford, 1840, where the jury held that it is very important to determine, whether the prisoner was of unsound mind at the time of doing such acts or if some disease was acting within him, by which he could not resist the committed acts. Later in the year 1843, the M’Naghten case, (1843) led to the landmark case of determining the insanity of an accused in the court of law.

Overview of the M’Naghten rule

The rule mentioned in M’Naghten’s case has been extracted from other tests which were earlier used to determine the insanity of an individual. The irresistible impulse test, The “Durham Rule” and The ‘Model Penal Code’ 

The case of M’Naghten briefly unfolds as in the year 1843, Mr. M’Naghten attempts the assassination of the then Prime Minister of England Sir Robert Peel but he however kills the secretary of the Prime Minister believing the secretary to be Prime Minister himself. The medical experts on the case considered Mr. Naghten to be of unsound mind. The incident was followed by public outrage as subsequently, the House of Lords asked the parliament to widen the definition of insanity. 

The judges in this case laid down five tests that shall be considered by a court of law when dealing with the insanity of an accused person: 

  1. Whether at the time of committing the offence, if the accused knew his acts were against the law but he still committed such acts because of delusion, 
  2. Whether the pleaded defence of insanity is a setup of the accused when he alleged that he suffered insane delusion,
  3. Whether the person was under a state of mind when he committed the wrongful acts, 
  4. If a person committed wrongful acts under an insane delusion, then is he excused from the liability, 
  5. Whether the medical professional who shall determine the insanity of the accused, who never saw the accused, but such professional was there during the whole trial, examination, etc. can be asked for his opinion by the court. 

The court while answering such question held that: 

  1. Every individual is presumed to be sane and has enough reasons to be held responsible for the crime committed until the contrary is proved to the court of law, 
  2. To plead the defence of insanity, it is to be established by the accused that at the time of committing such offence, the accused was under a delusion or was suffering from the absence of not knowing the nature of his acts, 
  3. If the accused was aware of the acts he did and if the acts are contrary to law, then such person shall be punished, 
  4. The medical professional who has never seen the accused before the trial, shall not be asked for his opinion-whether or not if he thinks the accused is of unsound mind, 
  5. When the acts are committed by an individual who is under delusion, and such acts conceal the truth of the acts he did, he shall be under the same responsibility as he would have been if he imagined them.

English law on defence of insanity 

The common law is the actual founder of the defence of insanity in contemporary times. The law of insanity has evolved from different cases, however, the case of M’Naghten was established to be a landmark case in the history of English law which considered insanity as a genuine defence in criminal cases. 

It was in the case of M’Naghten when judges established certain principles: 

  1. Every person is presumed to be sane and possesses a reasonable amount of reason to be held liable for the crimes they committed until the contrary is established, 
  2. To establish the defence of insanity, it must be proved that at the time of the commission of such offence, the accused was under some mental illness,
  3. The accused did not know the nature of the act he/she committed, and
  4. The accused did not know his/her acts were contrary to law. 

Under English law, the term “complete madness” was initially established as a defence to criminal cases by the common-law courts in the late 13th Century, and by the 18th Century, the doctrine of complete madness was evolved in the “wild beast test”. 

The initial codification of law under the English law was done by Criminal Lunatics Act 1800, to punish an individual named James Hadfield, who tried to kill King George III because he wanted to die and knew that an attempt to kill the king would lead to his death. The act was later broadened in scope by the establishment of The Trial of Lunatics Act, 1883, to amend the law respecting the trial and custody of insane persons charged with an offence. Lunacy Act, 1890 was passed in the year 1890 to consolidate the laws relating to lunatics in the jurisdiction of the crown. 

Laws on insanity in other countries 

In the United States of America, the Model Penal Code, 1962, developed a new law on insanity, which was considered not too strict like M’Naghten’s case and not too lenient like the irresistible impulse test. The American law, in Section 4.01 states that a person will not be responsible for criminal conduct if at the time of the commission of such conduct the person as a result of mental disease cannot appreciate the criminal conduct or the requirements of law.

Australia’s The Tasmanian Criminal Code Act, 1924, in Section 381, provides the defence of insanity on the grounds that if the evidence establishes that the accused was insane at the time of the commission of the crime, such person shall be acquitted and the jury must especially mention whether such accused was acquitted by them on grounds of insanity and while the primary burden of proof is on the accused the prosecution establishes the evidence against the defence. In circumstances where the accused does not present evidence of insanity, the prosecution shall produce evidence of sanity. 

In Canada, the Criminal Code, 1985, in Section 16 states that no person shall be criminally responsible for any act committed while suffering from a mental disorder which rendered his capability of understanding the nature and quality of the act. The section also states that everyone shall be presumed to be sane until the contrary is proved, in other words, it initially places a burden of proof on the accused to prove that he/she was insane at the time of the commission of the offence. 

In France, Section 64, France Penal Code, 1810 states that there can be no crime when the accused was in a state of madness at the time of the action or when he was under a force which he had not the power to resist. To determine the insanity the court shall appoint an attorney who shall conduct an inquiry into the mental health of the defendant.

Irresistible impulse test 

The irresistible impulse test is another type of defence concerning insanity, under this test, a person shall not be punished for crimes which he did not intend to commit and could never prevent or resist such crimes even though they knew the crime was wrong but couldn’t stop themselves due to mental illness. 

To prove irresistible impulse test, the accused must prove: 

  • The sufferance of mental illness, and 
  • The mental illness resulted in the inability of the accused to control his/her actions which were contrary to law. 

The irresistible impulse test was established as a direct criticism of M’Naghten Rules in the year 1886 in the case of Parsons v. State, 1886, where the Alabama Supreme Court asked questions like whether the defendant because of such mental disease had lost the power to choose between right and wrong, and if at the time such person was insane the alleged crime occurred must be concerning the mental disease of such person. 

Burden of proof 

It is an established principle of criminal jurisprudence that a person is presumed innocent until proven guilty and until then the burden to establish guilt beyond a reasonable doubt rests upon the prosecution and this onus of proof always lies on the prosecution however Section 84 of IPC is an exception to this rule.  

It was held in the case of Gelsing Pida Pawar v State of Maharashtra, 2010, that the burden of proof of circumstances to bring the case within the ambit of Section 84 of IPC rests upon the accused under Section 105 of Indian Evidence Act. However, the burden of proof on the accused is not equal to the burden of proof on the prosecution. 

In the case of Dahyabhai Chhaganbhai Thakker vs State Of Gujarat, 1964, it was held that:

  • The prosecution must prove beyond reasonable doubt that the accused has committed the offence, and such burden to prove always lies on the prosecution throughout the trial, 
  • There is a rebuttable presumption that the accused was not insane at the time of the commission of the offence and the accused may rebut such presumption by placing all the relevant evidence, oral, documentary, or circumstantial however the burden of proof upon him is not 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 of the commission of an offence, the evidence placed before the court by either party to the proceedings may raise a reasonable doubt before the court and the accused shall be entitled to an acquittal because the prosecution did not discharge the general burden of proof. 

In the case of Butu @ Madhua Oram vs State, 1985, the Orissa High court held that the accused is not called to prove the ingredient of Section 84 of IPC beyond reasonable doubt to get an acquittal from criminal charges. However, it is sufficient if the pieces of evidence shown lead to the inference that the requirements of Section 84 may be probable. 

Essentials of Insanity 

In the case of Sarka Gundusa vs State, 1969, the Orissa High Court laid down certain essentials of Section 84 of IPC: 

  • The accused must be of unsound mind, at the time of the commission of the offence,
  • The accused must be of insane mind at the time of the commission of the offence and not before and after the commission of the offence. 
  • The unsoundness of mind must be of such a nature, that the accused was incapable of knowing the consequences of the committed his/her acts. 

In the case of Ratan Lal vs The State Of Madhya Pradesh, 1970, the Supreme court of India held that “The crucial point of time for ascertaining the state of mind of the accused is the time when the offence was circumstances which preceded, attended and followed the mind as to be entitled to the benefit of Section 84 of the Indian Penal Code can only be established from the circumstances which preceded, attended and followed the crime.” 

Law Commission of India report 

The report highlighted the issues of Section 84 of IPC and stated that as soon as the test of insanity in the case of M’Naghten was established, it attracted criticism. The commission also considered the law of Australia, the USA, France, etc. and asked certain questions like: 

  1. Should the existing laws of insanity be amended or modified?
  2. The test relating to the offender’s mental capacity to know the act is wrong or to his incapacity to know that it is punishable? 
  3. Should the defence of insanity be available to cases where the offender was although aware of the wrongful acts yet still did such acts due to mental condition?

The commission answers the above questions: 

  • Amending the existing laws will create more dependency on medical opinion and whether medical experts will be available throughout the country,
  • The majority held no change concerning the test relating to insanity. However, a few held that test should be knowledge of what is wrong and others that it should be knowledge of what is punishable by law, 
  • To include “irresistible impulse” within the ambit of Section 84 of IPC, very little support was witnessed and the main objection was that it will make the trial more difficult for judges. 

While holding the above-mentioned reasons, the commission did not find it fit to amend Section 84 of IPC.  

Legal insanity vis-a-vis medical insanity 

Legal insanity is different from medical insanity because in legal insanity the court is concerned with the delusions which the accused suffered during the commission of the crime and that the accused is a person of unsound mind. Each person who is suffering from insanity cannot plead the defence of insanity in a court of law and only a person whose mental impairment made it impossible to judge if the acts committed by him are contrary to the law can plead the defence of insanity in a court of law. 

In other words, a person who suffers from mental illness at all times is called mentally insane and a person who suffers from mental illness and who has lost his ability to understand the nature of the offence committed by him shall be referred to as legal insanity. 

When a person is subjected to irregularities of mind, delusions or irresistible impulses, or any traits of a psychopath, all of these shall constitute medical insanity and a person will only get the benefit of Section 84 of IPC if he/she proves that he/she was suffering from any of such impairments at the time an unlawful act was committed. 

In the case of Surendra Mishra vs State Of Jharkhand, 2011, the Supreme Court of India held:

  • Every person who is suffering from mental disease is not ipso facto exempted from criminal liability, 
  • Section 84 of the Indian Penal Code is to prove legal insanity and not medical insanity, 
  • The burden is on the accused but he is not required to prove the same beyond all reasonable doubt, but merely satisfy the preponderance of probabilities. 

In the case of The State vs Chhotelal Gangadin Gadariya, 1957, the court observes that they are only concerned with ‘unsound-ness of mind’ as defined in Section 84 of IPC and not with ‘unsoundness of mind’ as understood in the medical science. A similar view was taken by the court in Surendra Mishra vs State of Jharkhand, 2011, and ruled that the accused who seeks pardon under Section 84 of IPC shall prove legal insanity and not medical insanity. 

The issues with the defence of insanity 

The misuse of the defence has led to many countries abandoning the defence of insanity. Countries like Germany, Argentina, and Thailand, have abolished the defence of insanity. The current understanding of insanity and understanding of neurology and absence of impulse contract, and then conducting rationality tests, is an obsolete manner of determining insanity. 

There are high chances of such defence being misused by the criminals since it is almost impossible to determine the insanity of a person based on acts committed by him/her and therefore the defence lawyer can take advantage of this defence to free the actual wrongdoer from imprisonment. 

The insanity defence simply unsettles the foundation on which the law was built, i.e. to punish the wrongdoer, and this is done by misusing the defence of insanity in a court of law when a criminal gets acquittal by pleading insanity. 

Proving insanity is a difficult task for the accused since the burden to prove insanity lies on the accused. To prove legal insanity is a difficult task unlike medical insanity since to establish legal insanity, the accused has to present concrete evidence and sometimes the accused fails to establish insanity and the court imprisons the accused and an innocent should be getting medical assistance undergoes imprisonment for a crime which he/she never intended to do.

Everything in a case concerning depends upon the understanding of facts and evidence before the judge, and if the judge is not satisfied, an actual insane person may suffer incarceration therefore, the understanding and knowledge of the judge is an essential part. 

It can be concluded that the defence of insanity has lost its actual foundation and now it is either a way of getting away from the liability for a crime or may attract imprisonment which is not even lawful. 

Criminal law aims to punish the guilty person who possesses ‘actus reus’ and ‘mens rea’ i.e. guilty act and guilty mind. However, in cases of insanity the accused usually does not possess the required ‘mens rea’ and therefore it is not justifiable to punish such a person. 

The defence of insanity is often criticized after being confused between medical insanity and legal insanity, however, the courts are only concerned with legal insanity. It is almost impossible to determine if the person was insane at the time of the commission of the offence by the physiatrist. 

The need to reform

Insanity as a defence has lost its real purpose and has now evolved as an instrument for criminals to get away from legal accountability and therefore the judiciary must revisit the concept of insanity and bring back the soul of the law.

Although the mechanism is doing efficient work to determine the illness of an individual, there are certain instances where an actual criminal gets acquittal and an insane person gets imprisonment. Therefore, these errors must be rectified and prevented. 

The tests applied to determine insanity are very lenient and so obsolete that it often relieves a violent criminal from the punishment of crime he committed and places an actual insane person under detention and sometimes under imprisonment for a long duration of time. 

The current mechanism instead of placing an insane person under medical assistance places such a person under police or judicial custody, which is a human rights violation of the ill person. Since the Indian courts often take much time in reaching a decision, an innocent person stays in prison for no reason except for his mental illness. 

The responsibility to administer mentally challenged persons shall be made mandatory by professionals belonging to the medical field since numerous persons may act as a threat to society and therefore such persons must be kept under observation until they recover. 

When a person pleads the defence of insanity, the courts must, after determining the gravity of the offence, send a person under medical supervision for some time, and the court shall ask the medical fraternity to determine if such person is insane. 

The need for psychiatrist hospitals must be encouraged, or a separate hospital for persons who plead the defence of insanity must be established where the doctors must be well versed with determining the actual mental capability of the accused. The medical assistance at such hospitals must be free of cost or nominal charges must be charged with the main aim of assisting the patient. 


The defence of insanity is a serious issue in contemporary times since the defence is used as a tool by hardened criminals to get away from criminal liability. The defence of insanity has numerous issues like difficulty in determining the mental incapacity of an individual. The process to determine such insanity is also very slow. Therefore, it creates an issue not only for those who are liable for an offence but also for those who are innocent and have some mental disorder. 

The current test to determine the insanity of a person is not very reliable since the court is concerned with only legal insanity which is determined by the acts of a person before, during, and after committing an act that is contrary to law. 

The laws of insanity need to be amended or abandoned since it has caused many issues in the legal mechanism. The defence of insanity plays a significant responsibility in protecting the human rights of the individual who is suffering from some mental disorder and therefore the task of determining the insanity shall be performed with utmost accountability. 


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