Mistake of Fact and Mistake of Law


Author: Nikita Anand, ChanakyaNational Law University, Patna

*This article has been written by the author while pursuing Certificate Course on Research Methodology with us.


Before understanding what is the mistake of facts and mistakes of law. Let’s get into some basic concepts, i.e. what is the General Defence?

General Defence is a set of excuses, which can be used or are used by the defendant to escape his liability in tort when the plaintiff brings an action against him, providing the essentials of the tort. The defendant can plead the defense only if his actions fall under the specified set of conditions, that goes attached to these defenses and failing to prove the reason for his actions, he can not escape from the liability arising out of it.

General defences are :[1]

  • Volenti non fit injuria, or the defence of  ‘consent’
  • Plaintiff, the wrongdoer
  • Inevitable accident
  • Act of  God.
  • Private Defence
  • Mistake
  • Necessity
  • Statutory Authority.

Mistake, falling under the defence of Torts, it can be classified into two sub-heads.

  1. Mistake of facts
  2. Mistake of  Law

Where the mistake of facts can be treated as a defence to reduce the liability, taking the plea of absence of mens rea; the mistake of law is no defence, assuming that apart from certain exceptions, everyone is well versed with the laws.


In general, a mistake of fact generally refers to a mistaken understanding by someone as to facts of a situation the mistake results in the person committing an illegal act.[2]

As the mistake of the fact can be used as a defence and is excusable, that mistake has to he reasonable and honest.


Mr. A and Mr. B were studying Contract Law, authored by XYZ in the library together . after some time Mr. B received a call from his home directing him to come home as soon as possible, in that case, he rushed back to his home and in a hurry, by mistake he took away the book of Mr. A with him. Here, in this case, Mr. B will not be held liable because of the mistake of facts.


Miss X , used to get her Pomeranian dog to walk every morning. On one fine morning, while talking on the phone with her friend Miss X lost hold of her dog. While looking for her dog, she found another dog of the same breed, assuming it to be her own dog, she took it home. While later she noticed that, the mark her dog had was not there and she mistakenly took another’s dog. Here, Miss X will not be liable as it was a mistake of facts.

At the same time, the mistake of fact can not be used as a defence when it has been done knowingly, despite knowledge.


A visited B’s house with two boxes of sweets, giving it to B, A specifically mentioned, that blue box is for him, whereas the red one is for C, his elder son. Afterward, B consumed both boxes of sweets, here B can not take the defence of mistake of fact stating that as both boxes were handed over to him, he assumed it to be his only. As, at the time of delivering the sweets itself, the conditions were specifically mentioned.

In the case of Morrison V. Ritchie & Co., a statement was published by the defendant that the plaintiff had given birth to twins, even if the defendant had done it in good faith, he was held liable, on the ground that the plaintiff was married 2 months ago only and the defendant was held liable for the offense of defamation and element of good faith was held immaterial in that case

Mistake as to a matter of fact essential to the agreement is dealt with under the Law of Contracts. Where section 20 of the law talks about the agreement to be void when both parties of the contract are under mistake as to the matter of fact.


A agreed to sell his house to B for 5 lakhs. Later it turns out that particular house had already been sold to Z by A’s father as both the parties were ignorant of this fact, the agreement is void.

Where Section 20 talks about both the parties being ignorant, sec 22 talks about that the contract is not voidable merely because it was caused by one of the parties to it being under a mistake as to the matter of fact.[3]

In  AyekamAngahal Singh v. TheUnion of India, an auction was held for the sale of fishery rights, where the plaintiff made the highest bid of Rs 40,000. The rent was 40,000 per year and the plaintiff sought to avoid the contract on the ground that he under mistake thought of Rs40,000 being the rent for 3 years . in this case,it washeld that since the mistake was unilateral, the contract was not affected thereby the same could not be avoided.[4]


Ignorantia Juris neminem excusat,i.e. ignorance of the law is no excuse.[5]

The mistake of law is the legal principle that refers to one or more mistakes that are made by an individual in understanding how applicable law is applied to their past activities which are under analysis by the court.[6]


Mr.S at crossing did not stop his car at a red signal. Traffic police charged him for breaking the traffic rules, here Mr. S can not plead that he was not aware of the law.

Generally, the mistake of law can not be taken as defence and is  not excusable as it is assumed that other than minor, lunatics and insane know the law of the country, where he/she resides but to some extent acting in good faith, can be the exception for the same

Specifically, the mistake of law can be used as a defense in four limited circumstances :[7]

  • When the law has not been published;
  • When the defendant relied on up a law or statute that was later overturned or deemed unconstitutional
  • When the defendant relied upon a judicial decision that was later overruled; or
  • When the defendant relied upon an interpretation by an applicable official.[8]

The maxim that ignorance of the law is no excuse for breaking it, has been developed from the ancient Roman Law. In the good old days, where the number of laws were less and were numbered, it was easy to remember and understand them, and it was justified that one should know all the laws.

In the time, where all our actions are regulated by law, if the mistake of law is allowed to be taken as the defence, everyone will start pleading the same and this will lead to the end of the purpose of justice. But there is more to it, we have so many forms of law,  and most of the Judgment delivered is in either English or Hindi language, what if a person knows neither English or Hindi? Also, there is overruling of judgments of one court by other higher court..sometimes apex court overruling its own judgment. In such cases, how a layman is supposed to know the laws and keep himself updated with the same.

Likewise, Article 35A of our Constitution was unknown to everyone except for the last year or so. One can’t find the Article printed in any of the Bare Acts of the Constitution or in the latest textbooks written by famous authors. Article 35A was added by the Constitution (Application to J&K) Order, 1954, by President of India on May 14, 1954, exercising the powers conferred by Article 370(1) of the Constitution and with the concurrence of the government of J&K. The absence of this article in statute books is proof of its non-publicity and non-promulgation.[9]

Also, in Martindale v Falkner, it was observed: “there is no presumption in this country that every person knows the law and it would be contrary to common sense and reasons if it was so.”[10]

As per section 21 of the Indian Contract Act,1872, the validity of the contract is not affected by the mistake of law and does not make the contract voidable on the same ground.


“Ignorance of the Law is no excuse “,[11]butwhere the motive is an important ingredient, it can be used as a defence. Section 76 and 79 of the IPC deals with the general exceptions under chapter IV.

Section 79: Act done by a person justified, or by mistake of fact believ­ing himself justified, by law.—Nothing is an offence which is done by any person who is justified by law, or who by reason of a mistake of fact and not by reason of a mistake of law in good faith, believes himself to be justified by law, in doing it.[12]

Illustration :

A police officer, being ordered by the court to arrest X, and after due inquiry he arrests Z  believing him to be X. Here, he has committed no offence.

Section 79: Act is done by a person justified, or by mistake of fact believ­ing himself justified, by law.—Nothing is an offence which is done by any person who is justified by law, or who by reason of a mistake of fact and not by reason of a mistake of law in good faith, believes himself to be justified by law, in doing it.[13]

In the State of Orissa v. Khora Ghasi, the accused while he was guarding his field, shot an arrow on the moving object, in good faith that it was bear but the shot results in the death of the person. Here, immunity under a mistake of fact can be availed.


In general, the mistake of fact can be used as a defence to escape the liabilities, taking the absence of mensrea as one of the important essentials; it must have to be honest, reasonable and bonafide in nature. On the other hand, the Mistake of law is no excuse, keeping in mind its repercussions and the onus falling on individuals to know the laws except minors, lunatics, and insane. However, there are few rare exceptions to this rule which gives exemptions from the liability arising out of Mistake of Law.

[1] Dr. R.K. Bangia,Law of Torts, page no. 29,2018.

[2]John Mcccurley, Is the mistake of fact ‘A defence to criminal charge’, available at http://www.nolo.com ( last seen 20th April’ 2020, 7:05 pm)

[3]DR. R.K. BANGIA, Contract – I, page no.89,2018.


[5]SivadasChettoor, Ignorance of law : can it be an excuse ?available at indiainfoline.com.(last seen 20th April’2020, 9:50 pm)

[6]Adv John, Mistake of fact vs Mistake of Law in Indian IPC,22nd September ‘2020.

[7]Mistake of Fact or Mistake of Law as a Defense in a Criminal Case, available at http://www.justia.com ( last seen 20th April’2020, 11:00 pm)


[9]Justice Bhanwar Singh & Dr. NK Bahl, Ignorance is not a bliss but…, May 26th 2019, available at www.in,dialegallive.com ( last seen, 21st April’2020, 8:00am)

[10] Id.

[11] Supra note 5.

[12]Http://www.indiankanoon.org>doc. ( last seen 21st April’2020,9:50 am)

[13] Id.