Distinguish between ' mistake of law' and 'mistake of fact' in the light of the
maxims ignorantia facit doth excusat and ignorantia juris non excusat.
A. Introduction
In criminal law, the concepts of “mistake of fact” and “mistake of law” play crucial roles in
determining the liability of individuals. These doctrines are rooted in the principle that an individual
should not be held criminally responsible if their actions were based on a misunderstanding that
negates the criminal intent. This post will discuss the definitions, provisions, illustrations, and case
laws related to mistake of fact and mistake of law.
B. Mistake of Fact
Mistake of fact arises when the accused misunderstands some fact that invalidates an element of
crime. This legal weapon can be used, where the accused is successful in proving that he/she was
mistaken for the existence/being of certain facts or ignorant of the existence of those facts. It is a
condition that such a mistake must concern a fact and not law and must also be reasonable. Section
14 and 17 of BNS accommodates the provision of mistake of fact.
The legal maxim, “ignorantia facti excusati ignorantia juris non excusat” which means ignorance of
fact is an excuse, but ignorance of the law is no excuse.
The Bhartiya Nyaya Sanhita, 2023, under Section 14 and Section 17, provides for the defense of
mistake of fact.
Section 14: “Act done by a person bound, or by mistake of fact believing himself bound, by law”:
This section exempts a person from criminal liability if they commit an act under the belief that they
are legally bound to do so, provided this belief is due to a mistake of fact.
For a crime to be committed, there must typically be a mens rea, or a guilty mind. Mistake of fact can
negate mens rea if it shows that the defendant did not have the intent required to commit the crime.
For example, if a person takes someone else‟s property believing it to be their own, they lack the
intent to steal.
In certain offences, known as strict liability offenses, the defense of mistake of fact is not available.
These offenses do not require proof of mens rea. For instance, statutory rape laws often impose
strict liability, meaning that a mistake regarding the victim‟s age is not a defense.
Illustration :
A soldier, ordered by his superior officer to fire at an enemy during combat, shoots
and kills a civilian mistaking him for the enemy. If the soldier genuinely believed
the civilian was an enemy combatant, he may claim a defense under Section 14 of
the BNS.
CASE LAW:
R v. Tolson involved Mrs. Tolson, who was charged with bigamy after remarrying under the belief that
her first husband, who had deserted her and been absent for several years, was dead. She had
received information leading her to believe in good faith that he had died. The legal issue was
whether this genuine and reasonable belief could serve as a defense to the charge of bigamy. The
court held that Mrs. Tolson‟s honest and reasonable mistake of fact regarding her husband‟s death
negated the mens rea required for the offense. Consequently, the court acquitted her, establishing
that a reasonable mistake of fact can be a valid defense in criminal law.
C. Mistake of Law
Section 17: “Act done by a person justified, or by mistake of fact believing himself justified, by
law”:
This section protects a person from criminal liability if they commit an act under the belief that it is
justified by law, provided this belief is due to a mistake of fact.
A person sees another individual breaking into a house at night and, believing it to be a burglar,
apprehends them. If it turns out the person was the homeowner who lost their keys, the apprehender
may claim a defense under Section 17, provided the belief was reasonable.
A mistake of law occurs when a person misunderstands or is ignorant of the law as it exists. Unlike a
mistake of fact, ignorance of the law is generally not a defense in criminal law. The maxim
“ignorantia juris non excusat” (ignorance of the law excuses not) applies, meaning that everyone is
presumed to know the law and cannot escape liability due to ignorance.
The Indian Penal Code does not provide a defense for mistake of law. The principle is captured in the
maxim itself, which is widely recognized and applied in Indian jurisprudence.
Illustration1: a person constructs a building on land, believing that they have the legal right
to do so, only to discover that the land is protected under environmental laws. The person
cannot claim a defense based on ignorance of environmental protection laws.
Illustration 2: A, a foreigner, kills a wild buffalo in India. He believes that killing a wild buffalo
to be lawful in India. „A‟ is guilty of killing the wild buffalo. He can’t take the defence that he
was unaware of the law.
Illustration 3: If a man is caught by a ticket conductor for travelling on a train without a
ticket. He cannot claim that he was not aware that a ticket is required while travelling on the
train and shall be punished under Section 138 of The Indian Railways Act, 1989.
D. Conclusion
The doctrines of mistake of fact and mistake of law serve to differentiate between errors that can
excuse criminal liability and those that cannot. While the BNS recognizes mistake of fact as a
potential defense under certain conditions, it firmly adheres to the principle that ignorance of the
law is no excuse.
