According to Black Law Dictionary, insanity means any mental disorder severe enough that it prevents a person from having legal capacity and excuses the person from criminal or civil responsibility.[1] Medical conception of insanity can be defined as a mental abnormality due to various factors existing in varying degrees. In wider connotation, it includes idiocy, madness, lunacy, mental derangement, mental disorder and every other possible form of mental abnormality known to medical science.

It recognizes sudden and uncontrollable impulse driving a man to kill or to cause injury within the scope of insanity. In law, insanity means a disease of mind which impairs the cognitive faculty i.e., the reasoning capacity of a man to such an extent so as to render him incapable of understanding the nature and consequence of his act. Emotional and volitional factors are excluded from the purview of legal concept of insanity.

Historical background
Since fourteenth century, the defence of insanity has been recognized in English courts, when complete madness was considered as a defense to a criminal charge. By 1518, it was well established that the lack of guilty mind and intellect meant a lack of criminal responsibility. By the eighteenth century, the complete madness definition had evolved into the wild beast test. It was the first test to check insanity that was laid down in the case of Arnold Case in 1724.[2]

Justice Tracy, a 13th century judge in King Edward's court, first formulated the foundation of an insanity defence when he instructed the jury that it must acquit by reason of insanity if it found the defendant to be a madman which he described as a man that is totally deprived of his understanding and memory, and do not know what he is doing, not more than an infant, than a brute, or a wild beast, such a one is never the object of punishment

Later in the year 1800, the landmark trial of Hadfield[3] set a new standard. The test laid down in this case is 'the ability to distinguish between good and evil' (Popularly known as Good and Evil Test or Insane Delusion Test). This decision was a landmark because it rejected two concepts previously held by the court.

First, it is not necessary for acquittal on the ground of insanity that be must be completely deprived of his mental faculties; second, it severed the tie between insanity and ability to distinguish between right and wrong. In Bowler's case[4] the House of Lords formulated the test of capacity to distinguish between right and wrong. However, this position of law was substantially modified by the McNaughton decision which formulates the basis of the present defense of insanity.

McNaughton Rule

The verdict of Daniel McNaughton[5] became a legendary precedent for the law concerning the defence of insanity since it laid down an assertive test for determining the defence of insanity. The facts of the case narrate that Daniel McNaughton was charged for the murder of Edmond Drummond, Private Secretary of Sir Robert Peel, the then Prime Minister. McNaughton was suffering under an insane delusion that Prime Minister Sir Robert Peel was the only reason for all his problems.

He mistook Drummond for Sir Robert and accordingly, shot and killed him. During the trial, the accused pleaded not guilty on the grounds of insanity. The court after conducting due trial and upon the jury's report acquitted McNaughton on the ground of insanity.

The test prescribed that:
the accused in order to get exemption from criminal responsibility on the ground of insanity, must prove that, owing to a defect of reason due to a disease of mind, he did not know the nature and quality of his act, if he did know this, that he did not know that he was doing wrong.

The public outrage after his acquittal prompted the creation of a strict definition of legal insanity which is known as the McNaghten Rules. The wrath generated and criticism leveled against the judgment compelled for a debate in Parliament. Consequently it was decided to take the opinion of the judges of the House of Lords with a view of getting the law clarified on the point.

Thus, accordingly on 19th June 1843 the judges were requested to give their opinion to the five questions put to them.

The extraction of the five questions is summarized as follows:

1. The first question was: What is the law respecting alleged crimes committed by person afflicted with insane delusion in respect of one or more particular subjects or persons; as, for instance, where at the time of the commission of the alleged crime, the accused knew he was acting contrary to law, but did the act complained of with a view, under the influence of insane delusion, of redressing or revenging some supposed grievance or injury, or of producing some supposed public benefit?
   
   
2. The second question was: What are the proper question to be submitted to the jury, where a person alleged to be afflicted with insane delusion respecting one or more particular subjects or person is charged with the commission of a crime, and insanity is set up as a defence?
   
   
3. The third question was: In what terms ought the question to be left to the jury as to the prisoner's state of mind at the time when the act was committed?
   
   
4. The fourth question is: If a person under an insane delusion as to existing facts commits an offence inconsequence thereof, is he thereby excused?
   
   
5. The fifth question was: Can a medical man conversant with the disease of insanity, who never saw the prisoner previously to the trial, but who was present during the whole trial and the examination of all the witnesses, be asked his opinion as to the state of the prisoner's mind at the time of the commission of the alleged crime, or his opinion whether the prisoner was conscious at the time of doing the act that he was acting contrary to law, or whether he was labouring under any and what delusion at the time?

The following proposition may be drawn from the answers given by the judges:

1. Every man is presumed to be sane and to possess sufficient degree of reason to be responsible for his crimes, until contrary be proved to the satisfaction of the jury or the court.
2. To establish defence on ground of insanity it must be clearly shown that at the time of committing the act, the accused was labouring under such a defect of reason from disease of mind that he did not know the nature and quality of the act he was doing was wrong.
3. If the accused was conscious that the act was one which he ought not to do and if that act was at the same time contrary to the law, he would be punishable.
4. A medical witness who has not seen the accused previous to the trial should not be asked his opinion whether on evidence he thinks that the accused was insane.
5. Where the criminal act is committed by a man under some insane delusion as to the surrounding facts, which conceals from him the true nature of the act he is doing, he will be under the same degree of responsibility as he would have been on the facts as he imagined them to be.

Irresistible impulse

This is a peculiar form of insanity. Its commonest form is impulsive homicidal mania. Cases of this kind are very numerous, their chief characteristic being an entire absence of motive. The victims are usually those who are nearest and dearest to the person who is assailed with this violent temptation to say, who in many cases knows that the temptation is coming on and begs those around him to have him confined until the impulse has passed away. An impulse to be irresistible must be one which cannot be resisted, not merely one which is not resisted.

The answers given by the judges in McNaghten Case have been the subject of much consideration and criticism by legal and medical writers ever since their birth. One of the common criticisms levelled against them is that they make no allowances for irresistible impulse, a species of insanity according to medical experts, which affects the will. According to them, insanity affects not only a man's belief but also, and indeed, more frequently his emotion and will. In such cases, according to them, although he was aware of the nature and quality of his act and knew it to be wrong, if he is irresistibly impelled to do what he did, he should be exempted from criminal responsibility.

Durham Rule

In Durhum v. United State[6] Durhum was charged of house breaking and he pleaded insanity in his defense. The Circuit Court of Appeals declared that the existing tests of criminal responsibility are obsolete and should be superseded. The existing tests included both the McNaughton Rule and the Irresistible Impulse test.

In this case the court evolved a new test, namely, simply that an accused is not criminally responsible if his unlawful act was the product of mental disease or mental defect. Mental disease and mental defect were defined. Only because the accused was suffering from a mental disease or mental defect at the time he committed the act in issue would not suffice. He would still be responsible for his unlawful act if there was no casual connection between such mental abnormality and the act.

Indian laws on insanity

The law relating to insanity is laid down in the Indian Penal Code (IPC), which in substance is the same as McNaughton Rule. But, section 84 uses a more comprehensible term unsoundness of mind instead of insanity.

Section 84 of IPC states:

Nothing is an offence which is done by a person who at the time of doing it, by reason of unsoundness of mind, is incapable of knowing the nature of the act that he was doing or that it was wrong or contrary to the law.

To be exempted under this section only proof of insanity is not enough. It should be clearly proved that:

1. The accused was of unsound mind
2. He was of unsound mind at the time of the commission of the act, not before or after and,
3. He, by reason of insanity, was incapable of knowing the act and that what he was doing was wrong and contrary to the law. It is not sufficient to prove merely the presence of mental derangement or psychotic illness. The accused must prove that his cognitive faculties were so impaired that he was deprived of understanding the nature of the act or distinguish right from wrong; wrong here means moral and not legal wrong.[7]

For want in this section, unsoundness of mind is used to describe only those conditions that affect the cognitive capacity of an individual. So, every person who is mentally ill is not relieved from his responsibilities. Here the law makes distinction between medical and legal insanity. Another requirement under law is that this unsoundness of mind should exist at the time of commission of the act. It is only the presence of insanity at the time of the act which matters and' not before or after that.

If insanity exists at the time of trial it can only lead to postponement of trial but not to acquittal of the accused. Lastly if accused did not know the nature of the act he was committing then he is not responsible for it. Similarly, if he knew the nature of the act but did not know whether it was wrong or contrary to the law he is not liable. On the other hand if the person did not know the nature of the act but knew that it is wrong as contrary to law he is held responsible.

This section does not confer immunity from criminal liability in every case of insanity of the accused. Coupled with the insanity of the accused there must be the additional fact that at the time of the commission of the act, he is in consequence of the insanity, incapable of knowing the nature of the act or that he is doing what is either wrong or contrary to law. It is settled principle that every person is sane unless contrary is proved and the onus of proving insanity is upon who is pleads it as a defence.

However, this requirement of proof is not heavy as on the prosecution to prove the offence and is based on balance of probabilities. Thus the section not only recognizes the unsoundness of mind that makes the person incapable of knowing the nature of the act, or that the act was contrary to law or that the act was wrong but emphasis is laid on the fact that such incapacity must exist at the point of time when the alleged act was committed.

Previous conduct and conduct at the time of committing the offence and subsequent conduct are relevant under section 84. Prior and subsequent incapacity will not be taken into consideration while judging the defence of insanity but however such prior and subsequent incapacity would form part of relevant facts in recording of evidence.

The procedure for the trial of insane person is laid down in Chapter XXV of the Code of Criminal Procedure, 1973. Sections 328 to 339 of the Code of Criminal Procedure deal with the examination of an insane person by a medical officer, postponement of the trial of the case, released on bail, detaining in safe custody, resume the inquiry after the person concerned ceases to be of unsound mind or having capable of making his defence, acquittal on the ground of unsoundness of mind at the time of committing the offence and sending to a public lunatic asylum.

Burden of proof
According to 105 of the Indian Evidence Act, 1872, the burden of proof in a case where insanity is set up as a defence in a criminal charge is said to rest upon the accused person. In respect of criminal cases, it is an accepted principle of criminal jurisprudence that the burden is always on the prosecution and never shifts.

This flows from the cardinal principle that the accused is presumed to be innocent unless proved guilty by the prosecution and accused is entitled to the benefit of every reasonable doubt.

Section 84 requires that if the plea of insanity put up by the accused is to be sustained, the accused has to establish by positive evidence that not only was he insane generally, but the fact that insanity existed at the crucial point of time when the offence was committed.

In the case of State of Madhya Pradesh v. Ahamadullah[8], it was observed that burden of proof is on the accused to prove that he was suffering from unsoundness of mind at the time when he did the act.

The Supreme Court also upheld the principle in the case of S.W. Mohammed v. State of Maharastra[9] and said that the accused have to prove that he is insane. However, this requirement of proof is not heavy as on the prosecution to prove the offence and is based on balance of probabilities.

The apex court in Shrikant Anandrao Bhosale v. State of Maharashtra (2002)7 SCC 748, The burden of proving the existence of circumstances bringing the case within the purview of Section 84 lies upon the accused under Section 105 of the Indian Evidence Act. Under the said section, the Court shall presume the absence of such circumstances. Illustration (a) to Section 105 is as follows:
(a) A, accused of murder, alleges that, by reason of unsoundness of mind, he did not know the nature of the act. The burden of proof is on A.

The apex court in Sudhakaran v. State of Kerala (2010) 10 SCC 582, while referring to Dahyabhai v. State of Gujarat AIR 1964 SC 1563 held as follows:
Thereafter, upon further consideration, this Court defined the doctrine of burden of proof in the context of the plea of insanity in the following propositions:

1. The prosecution must prove beyond reasonable doubt that the appellant 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 appellant was not insane, when he committed the crime, in the sense laid down by Section 84 of the Indian Penal Code: the appellant 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.

The Madras High Court in R. Maruthu v. State (2013) 2 MWN (cri)447(DB) observed that,

The Judgments, commencing from Bhikari v. State of UP. (supra), have been followed consistently by the Hon'ble Supreme Court and the law stands well settled on the following aspects:

1. The burden of proving commission of an offence is always on the prosecution and that the same never shifts. Equally well settled is the proposition that if intention is an essential ingredient of the offence alleged against the accused, the prosecution must establish that ingredient also.
   
   
2. The burden of proving that he was incapable of knowing the nature of the act or of knowing that what he was doing was either wrong or contrary to law is upon the accused.
   
   
3. The standard of proof, which the accused has to satisfy for the discharge of the burden cast upon him under section 105 of the Indian evidence act, 1872, is not of the same rigour as the burden of the prosecution to prove the charge beyond a reasonable doubt. It is enough for the accused to show, as in a civil case, that the preponderance of probabilities is in his favour.

The Madras High Court in Chellathurai v. state 2012 SCC Online Mad 891, observed that the burden of proof rests on an accused to prove his insanity, which arises by virtue of Section 105 of the Indian Evidence Act, 1872 and is not so onerous as that upon the prosecution to prove that the accused committed the act with which he is charged. The burden on the accused is no higher than that resting upon a plaintiff or a defendant in a civil proceeding

The apex court in Hari Singh Gond v. State of Madhya Pradesh, (2008) 16 SCC 109, AIR 2009 SC 31 held as follows:
The onus of proving unsoundness of mind is on the accused. But where during the investigation previous history of insanity is revealed, it is the duty of an honest investigator to subject the accused to a medical examination and place that evidence before the Court and if this is not done, it creates a serious infirmity in the prosecution case and the benefit of doubt has to be given to the accused.

The onus, however, has to be discharged by producing evidence as to the conduct of the accused shortly prior to the offence and his conduct at the time or immediately afterwards, also by evidence of his mental condition and other relevant factors. Every person is presumed to know the natural consequences of his act

Critical analysis of laws on insanity in India

To invoke the benefit of section 84, it must be proved that at the time of commission of the offence, the accused was insane was of such a degree as to fulfill one of the tests laid down in section 84. These two tests are:

1. The accused was incapable of knowing the nature of the act,
2. The accused was incapable of knowing that the act was wrong or contrary to law.

The insanity should be of such a nature that it destroys the cognitive faculty of the mind to such an extent that a person is incapable of knowing the nature of his act or what he is doing is wrong or contrary to law. The Calcutta High Court in Geron Ali v. King[10] recognized the twin test of insanity under section 84. The court held that the accused gets the defence if he was incapable of knowing the nature of the act or when he did not know that what he was doing was either wrong or it was contrary to law.

He, however, does not get the defence if he knew that what he was doing was wrong. Again the Calcutta High Court in Ashiruddin v. King[11] allowed the defence of insanity though the accused had sacrificed his son of five years while acting under the delusion of a dream, believing it to be right, though he knew what he did was contrary to law in as much as he tried to conceal his act from the watchman.

Later the Allahabad High Court in Laxmi v. State[12] did not agree with the view of Calcutta High Court and held that if the cognition and reason are found to be still alive and vibrant, it will not avail a man to say that at the crucial moment he had been befogged by an overwhelming cloud of intuition which cast deep dark shadows over his mental faculties.

In Hazara Singh v. State of Punjab[13], the Punjab High Court observed that In order to earn immunity from criminal liability the disease, disorder or disturbances of mind must of degree, which should obliterate perceptual or volitional capacity. A person may be a fit subject for confinement in a mental hospital, but that fact alone will not permit him to enjoy exemption from punishment.

Crotchetiness of cranks, feeble mindedness, any mental irresponsibility, mere frenzy, emotional imbalance, heat of passion, uncontrollable anger or jealously, fits of insensate hatred, or revenge , moral depravity, dethroning , reason , incurable perversions, hypersensitive excitability, ungovernable fits of temper, stupidity, obtuseness, lack of self-control, gross eccentricity and idiosyncrasy and other similar manifestations, evidencing derangement of mental functions, by themselves, do not offer relief from criminal responsibility.

The Supreme Court in Dayabhai Chhaganbhai Thakkar v. State of Gujarat[14] held that the crucial point of time for ascertaining the state of mind of the accused is the time when the offence was committed. Whether the accused was in such a state of mind as to be entitled to the benefit of section 84 of IPC can only be established from the circumstances which preceded, attended and followed the crime.

In Sheralli Wali Mohammed v State of Maharastra[15] the Supreme Court held that the law presumes every person of the age of discretion to be sane unless the contrary is proved. The mere fact that no motive has been proved why the accused committed an offence, would not indicate that he was insane, or that he did not have the necessary mens rea for the commission of the offence.

The Supreme Court in Shrikant Anandrao Bhosale v. State of Maharashtra[16] held that when a plea of legal insanity is set up, the crucial point of time for ascertaining the state of mind of the accused is the time when the offence was committed. Whether the accused was in such a state of mind as to be entitled to the benefit of section 84 of the IPC can only be established from the circumstances which preceded, attended and followed the crime. Undoubtedly, the state of mind of the accused at the time of commission of the offence is to be proved so as to get the benefit of the exception.

Crucial Point Of Time:
The Supreme Court in Shrikant Anandrao Bhosale v. State of Maharashtra (2002)7 SCC 748 held that:
when a plea of legal insanity is set up, the crucial point of time for ascertaining the state of mind of the accused is the time when the offence was committed. Whether the accused was in such a state of mind as to be entitled to the benefit of section 84 of the IPC can only be established from the circumstances which preceded, attended and followed the crime. Undoubtedly, the state of mind of the accused at the time of commission of the offence is to be proved so as to get the benefit of the exception.

The Hon'ble Madras High Court in Velan v. State 2016 SCConline Mad 11707 observed:
When a plea of legal insanity is set up, the court has to consider whether at the time of commission of the offence the accused, by reason of unsoundness of mind, was incapable of knowing the nature of the act or that he was doing what was either wrong or contrary to law.

The apex court in Mariappan v. State of Tamil Nadu CDJ 2013 SC 232, observed that it is now well settled that the crucial point of time at which unsoundness of mind should be established is the time when the crime is actually committed and the burden of proving this lies on the [appellant].
As concluded, we also reiterate that at the time of commission of offence, the physical and mental condition of the person concerned is paramount for bringing the case within the purview of Section 84.

Medical Insanity V/s Legal Insanity

The apex court in Hari Singh Gond v. State of Madhya Pradesh, (2008) 16 SCC 109mAIR 2009 SC 31 held as follows:
Section 84 lays down the legal test of responsibility in cases of alleged unsoundness of mind. There is no definition of unsoundness of mind in IPC. The courts have, however, mainly treated this expression as equivalent to insanity.

But the term insanity itself has no precise definition. It is a term used to describe varying degrees of mental disorder. So, every person, who is mentally diseased, is not ipso facto exempted from criminal responsibility. A distinction is to be made between legal insanity and medical insanity. A court is concerned with legal insanity, and not with medical insanity.

The apex court in Surendra Mishra v. State of Jharkhand (2011) 3 SCC(Cri.) 232, opined that an accused who seeks exoneration from liability of an act under Section 84 of the Indian Penal Code is to prove legal insanity and not medical insanity.

Expression unsoundness of mind has not been defined in the Indian Penal Code and it has mainly been treated as equivalent to insanity. But the term insanity carries different meaning in different contexts and describes varying degrees of mental disorder. Every person who is suffering from mental disease is not ipso facto exempted from criminal liability.

The mere fact that the accused is conceited, odd, irascible and his brain is not quite all right, or that the physical and mental ailments from which he suffered had rendered his intellect weak and affected his emotions or indulges in certain unusual acts, or had fits of insanity at short intervals or that he was subject to epileptic fits and there was abnormal behaviour or the behaviour is queer are not sufficient to attract the application of Section 84 of the Indian Penal Code.

As observed by the apex court in in Sudhakaran v. State of Kerala (2010) 10 SCC 582, Insanity in medical term is distinguishable from legal insanity. Where the offender is suffering from the disease of schizophrenia, The medical profession would undoubtedly treat the appellant herein as a mentally sick person (mentally insane). However, for the purposes of claiming the benefit of the defence of insanity in law, the appellant would have to prove that his cognitive faculties were so impaired, at the time when the crime was committed, as not to know the nature of the act (legally insane).

The legal concept of insanity widely differs from that of the medical concept. Every legal insanity is medical insanity but every medical insanity may not be legal insanity. The concept of legal insanity differs considerably from the concept of medical insanity and it is not every form of insanity or madness that is recognized by law as a sufficient excuse. The distinction between medical insanity and the legal insanity lies in the cognitive faculty of a man that affecting the will or emotions.

It is only the legal insanity that comes within the purview of section 84 of IPC. There are several types of mental ailments, but none is recognized in law, unless the elements of section 84 are satisfied. When a person is not insane but is imbalanced and excited, and is probably labeling under some kind of obsession or hallucination, section 84 cannot be of any help to him.

References:

1. Garner, B. A. (2008). Black's Law Dictionary. 8th Ed. p. 810
2. R. v. Arnold, (1724) 16 St. Tr. 695
3. R v Hadfield, (1800) 27 St. Tr. 128
4. (1812) 1 Collinson Lunacy 673
5. R v. Daniel M'Naughten (1843) Revised Reports Vol 59:8ER 718 (HL)
6. Durham v. United States, (1954) 214 F.2d.862
7. Luvana Vaghumal Kherajmal v. State, 1955 CriLJ 63 (Gujarat)
8. AIR 1961 SC 998
9. AIR 1972 SC 216
10. AIR 1941 Cal 129
11. AIR 1949 Cal 182
12. AIR 1959 All 534
13. AIR 1954 Punj. 104
14. AIR 1964 SC 1563
15. AIR 1972 SC 2443
16. (2002)7 SCC 748