Insanity is a defense and exemption that have been mentioned in chapter IV of the Criminal Procedure Code. But in reality claiming the defense of insanity is harder than it seems on paper due to multiple reasons and complication plus taking into concern the fact the onus/burden on proof lies on the one who claims such insanity. For multiple reasons insanity has been divided into two types of insanity medical and legal insanity, before getting into what these types of insanity mean or how are they distinguished we have to understand the basic definition of insanity.

The definition of insanity has two types one is in the terms of a layman and the other in aspect and regards to law, the definitions are given below:

Dated: a severely disordered state of the mind usually occurring as a specific disorder
Law: unsoundness of mind or lack of the ability to understand that prevents one from having the mental capacity required by law to enter into a particular relationship, status, or transaction or that releases one from criminal or civil responsibility.

These are the two basic definitions of insanity, in simple understated words insanity should mean the mental incapacity to make decision or a mental illness or disorder preventing one from enjoying a normal social life.

Now we will be taking a look into what is medical and legal insanity and then go over the fine points and case laws regarding both medical as well as legal insanity, the definitions are given below:

Medical insanity

Medical insanity doesn�t mean a person is mad or crazy. It most of the time means that the person is on medicines or under consultation with a psychiatrist or therapist but are able to make informed decisions and can do for them and lead a normal life.

Legal insanity

It is a situation in which a person has to be placed under direct supervision having no decision making abilities in things related to finance or else and another person has to take their responsibility and do their bidding.

Insanity is mostly considered a mental thing but in certain cases it can be due to something physical like Alzheimer or senile dementia etc. A person maybe mentally ill and not legally insane small things like stress anxiety are also mental illness. But to prove legal insanity it takes 3 psychiatrists to declare a person to be legally insane and then the judge of the court declares the person to be insane and not fit to function in society worst case scenario is when they are sent to psych ward. In short in case of legal insanity one looses his/her recognition of juristic persona and also creates incapacity.

After seeing the basic difference between medical and legal insanity it is time that we look into more legal terms to define or characterize legal insanity.

Mental illness of such a severe nature that a person cannot distinguish fantasy from reality, cannot conduct her/his affairs due to psychosis, or is subject to uncontrollable impulsive behavior. Insanity is distinguished from low intelligence or mental deficiency due to age or injury. If a complaint is made to law enforcement, to the district attorney, or to medical personnel that a person is evidencing psychotic behavior, he/she may be confined to a medical facility long enough (typically 72 hours) to be examined by psychiatrists who submit written reports to the local superior/county/district court.

A hearing is then held before a judge, with the person in question entitled to legal representation, to determine if she/he should be placed in an institution or special facility. The traditional test of insanity in criminal cases is whether the accused knew the difference between right and wrong, following the M'Naughten Rule from 19th Century England. Most states require more sophisticated tests based on psychiatric and/or psychological testimony evaluated by a jury of laypersons or a judge without psychiatric training.

The law that relates itself to unsoundness/insanity of mind has been discussed thoroughly in current judgments of the Supreme Court in the case of Surendra Mishra vs. State of Jharkhand AIR 2011 SC 627.

The things those were highlighted in this are elaborated below:

1. The accused has to prove legal insanity and not the medical insanity
2. Every person who is suffering from mental disease is not ipso facto exempted from criminal liability.
3. The onus of proving insanity or unsoundness of mind which is one of the exceptions mentioned in Chapter IV of the CrPC, lies on the accused on preponderance of probabilities. To discharge the onus, the accused must prove his conduct prior to offence, at the time or immediately after the offence, with reference to his medical condition. Whether the accused knew that what he was doing was wrong or it was contrary to law is of great importance and may attract culpability despite mental unsoundness having been established.
4. The accused has to prove legal insanity beyond all reasonable doubt.

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 burden of proof rests on an accused to prove his insanity, which arises by virtue of Section 105 of the Indian Evidence Act, 1872 (in short the �Evidence Act�) and is not so onerous as that upon the prosecution to prove that the accused committed the act with which he is charged.

Origin Of The Rules On The Plea Of Insanity

The insanity law as a defense has been in existence from many centuries. But, it took a legal status from the last three centuries. The history of the law of insanity can be traced back to the 1700s.

The first case which dealt with the law of insanity was R v. Arnold (1724), in which Edward Arnold attempted to kill and even wound Lord Onslow and was tried for the same. The evidence clearly showed that the accused was suffering from a mental disorder. Tracy, J. observed:
�If he was under the visitation of God and could not distinguish between good and evil, and did not know what he did, though he committed the greatest offence, yet he could not be guilty of any offence against any law whatsoever.�

As stated in the aforementioned case, a person can demand immunity if, due to his unsoundness of mind, he was incapable of distinguishing between good and evil and did not know the nature of the act committed by him. This test is known as the �Wild Beast Test.�

The second test evolved in Hadfield�s case (1800). Hadfield was discharged from the army on the ground of insanity and was tried for high treason in attempting to assassinate King George III. The counsel of the accused, Lord Thomas Erskine, defended him and proved in front of the judge that Hadfield only pretended to kill the King and is not guilty, on the ground of insane delusion from which the accused was suffering.

Erskine stated that insanity was to be determined by the fact of fixed insane delusion and that such delusion under which the defendant acted is the main reason for his crime. This test was known as the �Insane Delusion Test.�

Finally, the third test was formulated in Bowler�s case (1812). In this case, Le Blanc, J. stated that the jury has to decide when the accused committed the offence, whether he was capable of distinguishing right from wrong or under the control of an illusion. After the Bowler�s case, the courts have placed more emphasis on the capacity of the accused to distinguish right from wrong, though the test was not that clear.

Mc�naughten�s Rule

There have been several tests from time to time, like the Wild Beast Test, Insane Delusion Test, etc. But the most important is the �Right and Wrong Test� formulated in M�Naughten�s case.

The hearing of M�Naughten and his release was a topic of discussion in House of Lords, and as a consequence, they called upon fifteen judges to decide on the question of criminal liability in the cases where the accused is incapable of understanding the nature of the act and also answered the questions advanced. Fourteen judges had the same answers. The view of the majority was given by Tindal C.J., these answers to the questions are known as M�Naughten�s Rule.

The following principles were cited:

1. If the person knew what he was doing or was only under a partial delusion, then he is punishable
2. There is an assumption that every man is prudent or sane and knows what he is doing and is responsible for the same.
3. To establish a defense based on insanity, it must be ascertained, at the time of perpetrating the act, the accused was in such a state of mind as was unable to know the nature of the act committed by him.
4. A person who has sufficient medical knowledge, or is a medical man and is familiar with the disease of insanity cannot be asked to give his opinion because it is for the jury to determine, and decide upon the questions.

Indian Law On The Defence Of Insanity

Insanity is provided in accordance with Section 84 of the Indian Penal Code as a defense under Indian Law. However, the term �insanity� is not used under this provision. The Indian Penal Code uses the sentence �mental soundness.� In accordance with the code, the defense of insanity, or that can also be called defense of mental insanity, comes from M�Naughten�s rule.

In Section 84 of the Indian Penal Code, a person of an unsound mind shall act:
Nothing is an offence committed by someone who is currently unable to know the nature of the act or does what is wrong or contrary to legislation due to a lack of a sound mind.

Nevertheless, it should be noted that the framers of the IPC preferred to use the expression �insanity of mind� instead of the term �insanity.� Insanity�s scope is very limited, while the mind�s insanity covers a large area.

For this defense, the following elements are to be established:

1. The accused was in a state of unsoundness of mind at the time of the act.
2. He was unable to know the nature of the act or do what was either wrong or contrary to the law. The term wrong is different from the term contrary to the law.

If anything is wrong, it is not necessary that it would also be �contrary to the law.� The legal conception of insanity differs significantly from medical conception. Not every form of insanity or madness is recognized as a sufficient excuse by law.

Characteristics Of Legal Insanity

1. Incapacity To Know The Nature Of The Act

   The word �incapacity to know the nature of the act� embodied in Section 84 of the Indian Penal Code refers to that state of mind when the accused was unable to appreciate the effects of his conduct. It would mean that the accused is insane in every possible sense of the word, and such insanity must sweep away his ability to appreciate the physical effects of his acts
    

2. Incapacity To Know Right Or Wrong

   In order to use the defence of insanity under the latter part of Section 84, namely �or to do what is either wrong or contrary to the law,� it is not necessary that the accused should be completely insane, his reason should not be completely insane, his reason should not be completely extinguished. What is required, is to establish that although the accused knew the physical effects of his act, he was unable to know that he was doing what was either �wrong� or �contrary to the law.�
   
   This part of Section 84 has made a new contribution to criminal law by introducing the concept of partial insanity as a defence against criminal insanity. However, as a practical matter, there would probably be very few cases in which insanity is pleaded in defence of a crime in which the distinction between �moral� and �legal� error would be necessary. In any crime, insanity can undoubtedly be pleaded as a defence, yet it is rarely pleaded except in murder cases. Therefore, in a case, this fine distinction may not be very useful for the decision. The Indian penal code has advisably used either �wrong or contrary to the law� in Section 84, perhaps anticipating the controversy.
    

3. Irresistible Impulse As Defense

   Irresistible impulse is a sort of insanity where the person is unable to control his actions even if he has the understanding that the act is wrong. In some cases, the Irresistible Impulse Test was considered to be a variation of Mc�Naughten�s rule; in others, it was recognized to be a separate test. Though the Irresistible Impulse Test was deemed to be an essential corrective on Mc�Naughten�s selective perception, it still had some criticisms of its own.

Conclusion
It is suggested that there should be a well-defined definition of the term �mental insanity� to avoid the various controversies and confusions that arise in understanding and differentiating between the �mental disease� and the actual insanity of mind sought by the Code or the so-called �legal insanity� in order to make the defence available to the accused.

Section 84 of the Code should be amended to incorporate the partial defence of diminished responsibility for murdering insane persons. This change shall be made on an equal footing with the defence of diminished responsibility as accepted under the defence of insanity as specified by English criminal law.

The scope of Section 84 should be expanded to incorporate the defence of automatism under the defence of an unhealthy mind, just as it is recognized by the English criminal law system.

Bibliography
Web links

• https://advocatetanmoy.com/2018/03/02/distinction-between-legal-insanity-and-medical-insanity/
• https://www.merriam-webster.com/dictionary/insanity
• https://www.lawyersclubindia.com/experts/What-is-the-difference-between-medical-insanity-and-legal-insanity--227176.asp
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4676201/
• https://www.topsecretwriters.com/2013/05/the-legal-system-insanity-vs-mental-illness/
• https://www.psychologytoday.com/us/blog/in-therapy/200907/the-definition-insanity

Journals

• Morse SJ, Bonnie RJ. Abolition of the insanity defense violates due process. J Am Acad Psychiatry Law. 2013;41:488�95
• Gostin LO, Larry OG. A Human Condition: The law relating to mentally Abnormal Offenders. Vol. 2. MIND; 1977.
• Neville K. The Insanity Defense: A Comparative Analysis Senior Honors Theses. Paper 244. 2010.

Books

• Gaur KD. Textbook on the Indian Penal Code. New Delhi: Universal Law Publishing; 2009.

Reference readings

• https://www.psychologytoday.com/us/blog/in-therapy/200907/the-definition-insanity