Insanity and the Law: How a 19th Century Test is Used to Prove Insanity Under Criminal Law

By Sanchali Bhowmik

Part IV of the Indian Penal Code (“IPC”) ranges from Section 76 to Section 106 IPC and
comprises the various general exceptions: from the acts of a minor to the unsoundness of the
mind of the persons. Section 84 IPC specifically discusses Insanity, or in a broader manner, the
unsound mind of an individual while committing a crime. This section explains that any act
committed by a person of an unsound mind will not be actionable and they won’t be held liable
for any offense while being in the state of insanity. The burden to prove the insanity would rest
upon the defendant (one who claims this defense) to prove that they weren’t able to understand
the consequences of their act and couldn’t distinguish between right or wrong owing to lack of a
sound mind. Hence, the presumption under this defense would be that the person was sane or of
a sound mind while committing the offense and the contrary would need to be proved by
Though the word or the meaning of ‘Insanity’ has not been explicitly stated in this section of the
IPC, it focuses on its aspects in a broader term by describing the exception of the ‘Unsoundness
of Mind.’ The concept of Insanity has been long known to the world and came into prominence
from the 1700s with the various tests that emergedHowever, in this article, we shall be
discussing the test that the Indian jurisprudence follows i.e. the Mc’Naughton’s test. The test laid
down in the case of R v Mc’Naughton (1843), is currently followed under Section 84 of IPC in
India. Apart from the Mc’Naughton’s Test, there are several other tests as well. The Wild Beast
Test and Insane Delusion Test is another. 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 and this test is called the the wild beast test.
However, the Mc’Naughton’s Test has several important points of the other tests and hence is the
most efficient with respect to determining the state of mind of an individual. This test has been
the guiding light for determining the liability of a person of an ‘Unsound Mind’ and hasn’t been
modified since the time it was incorporated.
Mc’Naughton’s Rules:

The test laid down in the case of R v Mc’Naughton is the most extensive and the most accurate
test to determine whether the defense of insanity applies or not. In this case, Daniel
Mc’Naughton was under the insane delusion that the Prime Minister at that time Sir Robert Peel
was the sole reason for all his problems. Hence, he decided to kill the Prime Minister. However,
he mistook the Personal Secretary of the PM Mr. Edmond Drummond to be the Prime Minister
and subsequently killed him.
He tried to plead the defense of Insanity as he didn’t have the knowledge of the adverse
consequences of his actions and also couldn’t distinguish between right and wrong. The Fifteen
Judge Bench was constituted in the House of Lords to decide upon this case and while giving the
judgment they laid down some rules that came to be known as the Mc’Naughton Rules which
were as follows:
a. If a person has partial delusion and could understand to a reasonable extent what is right
or wrong, he/she won’t be able to plead the defense of insanity.
b. There is a presumption that the person committing the criminal offense is sane or prudent
and knows what he is doing.
c. To establish the defense of Insanity, Defendant must prove that at the time of the offense,
the state of mind of Defendant was such that he/she wasn’t capable of determining the
consequences of their acts.
d. If the person has sufficient medical knowledge and is familiar with the state of Insanity,
he/she isn’t allowed to give their opinion and it’s upon the jury to decide and determine
the various questions of law.

This test is currently followed in India and also in several other countries as it is very
comprehensive in itself and gives a strict definition of Insanity in Legal terms. Though efforts
were made to change these rules with time, these have not been modified in India till yet and are
followed just like they were from the very beginning.
Irresistible Impulse Test
This test was laid down in the 19th Century. It was based on the concept of moral insanity which
meant that a person can act with an unsound mind even for temporary periods and are otherwise
sane persons. This conduct is involuntary on the part of Defendant and generally arises
spontaneously in a given situation. As a result, they can’t be held liable even if they are generally
able to comprehend what is right and what is wrong.
The liability can also vary as per different facts and circumstances of the case. It is seen to be a
variation to the Mc’Naughton Rules but had several criticisms of its own due to which more
importance is given to Mc’Naughton’s Rules worldwide.
In the case of Parsons v State, the court held that though Defendant was prudent and generally
had the ability to distinguish between right and wrong, he lost his power to choose the same

under the duress of mental disease at the time of the incident. These were the general tests that
have been laid down over the years. From all these, while some aren’t followed currently, the
rules laid in Mc’Naughton’s case still hold a lot of relevance and are widely followed.

Position in India:
India follows the Mc’Naughton Rules as stated in the general exception of Insanity under Section
84 of the Indian Penal Code. The term ‘Insanity’ ,though, has not been defined in the section, yet
all provisions have been stated under the concept of the ‘Unsoundness of Mind’ that is a broader
term with Insanity only being a component of it.
It has been stated under this section that a person who committed a wrongful act won’t be held
liable if he didn’t have the knowledge of the nature of his act or couldn’t distinguish between
right and wrong due to the unsound mind. The elements under this section are as follows:

  • The act must be done by a person of unsound mind
  • The person must also be unsound at the time of committing the offense.
  • The person must not be capable of distinguishing between right and wrong
  • The person should not be aware of the nature of his actions only because of the
    unsoundness of mind
    The burden of proving Insanity is always on the accused and the presumption is that the accused
    is a sane and prudent person. Even a mentally ill person ipso facto ( might not be exempted from
    criminal liability because he might be insane in medical terms but not in legal terms. This further
    led to the distinction between medical insanity and legal insanity of a person.
    As seen in the case of Hari Singh Gond v State of Madhya Pradesh, the Court has only given
    impoThe person should also have an unsound mind at the time of the commission of the crime
    which becomes necessary to determine their liability. However, the insanity before and after the
    commission of the crime is also very important to determine the liability of the person.
    In the case Ratan Lal v State of Madhya Pradesh, the defendant had put the grass in the land of
    the plaintiff Nemichand to fire. He didn’t have any malicious intention as such and was proved
    to be a Lunatic under the Indian Lunacy Act, of 1912. As a result, he wasn’t held liable in this
    case and availed the defense of Insanity in the trial court. However, the same case was appealed
    to the High Court that reversed the trial court’s decision and held the Defendant guilty. On
    appeal to the Supreme Court, it observed that a lunatic person would come under the purview of
    section 84 as they are also facing ‘Unsoundness of Mind.’ Further, it was also stated that the
    mental condition of the person should be directly related to the offense and should also not be
    remote in time. Therefore, the court gave its reasoning on the basis of:
  • Medical evidence provided for proving insanity
  • Unsoundness of mind of Defendant on the day of the accident caused
    The Irresistible Impulse Test as given earlier is not followed in India because it doesn’t fall
    within the ambit of Section 84 of the Indian Penal Code. A person won’t be absolved from
    his/her liability if they only had an irresistible impulse to commit an offense but could
    distinguish between right and wrong.
    The essentials to legal insanity:
  • Incapacity to know the Nature of the Act
  • Incapacity to Distinguish between Right and Wrong
  • Damage to the Person
  • ​​Insanity as a defense plays a very important role in protecting the interests of those who
    don’t have the ability at the right time to determine what is right and wrong. However, at the
    same time, it has a possibility of being misused by the people, as unsoundness of mind can
    also have several aspects related to it. It becomes a very subjective defense at times and
    depends largely upon the discretion of the jury. In some cases, they might exempt a person
    despite his soundness to such an extent that the nature of the act can’t be deciphered.
    Whereas, in others, a person may be held liable even when he/she was genuinely facing
    mental illness leading to unsound mind at that time.
    There is a need to ensure that some scope or extent is defined for the use of discretion by the
    Jury for which reasonable standards are required to be established. Therefore, there is a need
    to modify the Mc’Naughton Rules as the existing essentials or provisions keep it open to a
    lot many interpretations and personal discretion enters as a result.
    Further, there is also a need to clearly define certain terms so that there is no ambiguity with
    respect to the provisions relating to them. There might be some cases covering certain aspects
    of insanity that till then have not been included in Section 84 IPC such as Somnambulism or
    Sleepwalking as observed in the case of Pappathi Ammal v Unknown. The reasoning or the
    judgment of the courts, in such cases, should be based on the purpose for which the Section or
    that provision is introduced.
    Therefore, it can be concluded that on one hand, the laws/rules of Insanity have been very
    beneficial to the citizens with unsound minds, but on the other, there is a need to ensure that this is not misused by the people to escape their punishments by plugging all the gaps that exist in
    these laws.

Sanchali Bhowmik, a 3rd -year law student (L.L.B Hons.) at Jindal Global Law School

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s