Mistake in Contract: Fact vs Law

📑 On this page

⚡ The short answer

An agreement is void when both parties are mistaken about a fact essential to it, such as whether the goods exist. A mistake by only one party lets nobody escape. Nor does a mistake about Indian law, though a mistake about foreign law counts as fact. A wrong guess about value never counts.

🎬 The 30-second story

One name, two cars

“Rohan's Swift. ₹3 lakh. Final.”

🚗

Kabir

Two customers called Rohan traded in Swifts.

“Done! Here's ₹20,000 advance.”

🤝

Zoya

Zoya means the 2023 Swift. Kabir means the 2016 one.

“That's not the car I drove!”

🔑

Zoya

Delivery day. The old Swift rolls out.

“Take it or I keep the advance.”

⚖️

Kabir

Neither lied. Who wins?

Tara's ruling: Nobody gets the car. They never agreed on the same thing in the same sense. Both were honestly mistaken about an essential fact, so the agreement is void and Kabir returns the ₹20,000.

What counts as a ‘mistake’ in contract law?

A contract needs a meeting of minds (consensus ad idem): agreement on the same thing in the same sense. A mistake is an honest wrong belief that breaks this, either because each side meant a different thing, or because both shared a false assumption. Nobody lied or threatened; that separates mistake from fraud and coercion.

🧮 The formula

What real consent needs

📦

Same thing

🧠

Same sense

🌍

Real facts

✅

Real consent

When does a mistake make an agreement void?

🧭 Decision flow

Does the mistake kill the deal?

❓ Is the mistake about a law or a fact?

Law →

❓ Is it a law in force in India?

Foreign law is treated as fact.

Yes →

Not voidable. No escape.

No ↓

❓ Were both parties mistaken?

Yes →

❓ Is the fact essential, not just an opinion on value?

Yes →

Void from the start.

Benefits go back.

No →

Valid. A side point changes nothing.

No →

❓ Did the other side cause it by fraud or misrepresentation?

Yes →

Voidable by the misled party, for fraud or misrepresentation.

No →

Binding. Your mistake, your risk.

📌 What CLAT actually expects

The passage hands you the conditions. Tick each against the facts: both mistaken? About a fact? Essential? One missing tick and the deal survives.

Which facts are ‘essential’ to an agreement?

Essential means the mistake goes to the root: without that fact, the deal is about something different, or nothing.

🧩 At a glance

Mistakes that go to the root

🔥Existence

The thing was already gone: cargo lost, horse dead.

🚢Identity of the thing

Each side meant a different item.

📐Quantity or area

48 units of one measure vs 48 of another.

🏷️Title

Both thought the seller owned it.

📜Nature of the deal

Both thought it a lease; it was a gift deed.

💰Value: not essential

Thinking it's worth ₹2 lakh is opinion, not fact.

Quality is the grey zone. If both think a sculpture is antique and it's a modern copy, they still bought the sculpture they saw. That binds unless the missing quality makes it essentially different.

🕒 Timeline

Timing decides the doctrine

1
Before signing

The bike burns; nobody knows

Shared mistake: void for mistake.
2
Before signing

The bike burns; only the seller knows

No shared mistake. The seller must compensate the buyer.
3
After signing

The bike burns later

Valid contract becomes void by impossibility.

Why doesn't a one-sided mistake let you escape?

Because the other side did nothing wrong. If Zoya buys a guitar privately believing a rock star once played it, and Kabir never said so, that belief is her risk. A contract is not voidable merely because one party was mistaken.

⚔️ Side by side

Bilateral vs unilateral mistake

👥Bilateral

Both wrong about an essential fact

•Agreement is void
•Neither can enforce it
•Advances go back

👤Unilateral

Only one side wrong

•Contract binds
•Mistaken party bears the risk
•Narrow exceptions only

Test	Bilateral	Unilateral
Effect	Void	Valid, not voidable
If the other side caused it	n/a	Voidable for fraud or misrepresentation

⚠️ One-sided mistake plus a lie isn't ‘mistake’

If Kabir told Zoya the star played it, he caused her mistake. The contract is voidable at her option for fraud or misrepresentation, not void for mistake.

The exceptions: identity and the nature of the document

Two one-sided mistakes can still destroy consent. One is identity: the seller meant to deal only with a particular person and an impostor stepped in. The other is the nature of the document: someone who, without carelessness, signs a gift deed believing it a lease (non est factum, ‘not my deed’).

⚔️ Side by side

Mistaken identity: letter vs face to face

✉️At a distance

The seller knows only a name

•Impostor borrows a real firm's identity
•Seller meant to deal with that firm alone
•No contract: void

🧍Face to face

The seller deals with whoever is present

•Impostor lies about who he is
•Seller meant to sell to the person there
•Voidable for fraud

Test	At a distance	Face to face
Innocent buyer from the impostor	Must return the goods	Usually keeps them

Is a mistake of law treated differently from a mistake of fact?

Yes. Everyone is presumed to know the law of the land (ignorantia juris non excusat). If Aarav and Zoya sign a deal believing an Indian rule allows what it forbids, neither can plead mistake.

🎚️ The scale

How the law treats a legal mistake

← No excuseCounts like a fact →

Indian law

Contract not voidable.

e.g. a wrongly assumed tax exemption

Foreign law

Treated as fact: void if shared and essential.

e.g. a misread import rule abroad

Private right

Who owns what is a fact.

e.g. who holds title

Nobody here can be expected to know Dubai's law, so it's handled like a fact. And the Indian-law rule only stops you escaping the contract: money paid by mistake, even of law, is usually recoverable.

What happens to money paid under a void agreement?

It goes back. Whoever got an advantage under an agreement discovered to be void must restore it, and a forfeiture clause dies with the deal. So Kabir can't keep Zoya's ₹20,000.

Which cases built the rule?

🌽

Landmark case · 1856 · House of Lords

Couturier v Hastie

📋

What happened

A cargo of corn was sold as if at sea. Unknown to both sides, it had begun to rot and the master had already sold it off en route.

❓

The question

Must the buyer pay for a cargo that no longer existed?

🔨

What the court held

No. The deal assumed the corn existed; it did not, so there was nothing to buy.

What CLAT takes from it: A shared mistake about existence is the classic void agreement.

🚢

Landmark case · 1864 · Court of Exchequer

Raffles v Wichelhaus

📋

What happened

Cotton was sold ‘to arrive ex Peerless from Bombay’. Two ships called Peerless sailed, in October and December. Each side meant a different one.

❓

The question

Was there a contract?

🔨

What the court held

No. The parties never agreed on the same thing in the same sense, so the buyer was not bound.

What CLAT takes from it: Same words, different subject matter: no consensus, no contract.

✉️

Landmark case · 1878 · House of Lords

Cundy v Lindsay

📋

What happened

A rogue, Blenkarn, ordered linen by letter, signing to look like Blenkiron & Co, a respected firm. He resold the goods to Cundy, an innocent buyer.

❓

The question

Did the rogue get ownership he could pass on?

🔨

What the court held

No. Lindsay meant to deal only with Blenkiron & Co, so no contract arose; Cundy had to answer for the goods.

What CLAT takes from it: Where identity matters, the deal is void and innocent buyers lose.

📐

Landmark case · 1998 · Supreme Court of India

Tarsem Singh v Sukhminder Singh

📋

What happened

In a land sale with ₹77,000 earnest, the seller meant 48 kanals; the buyer meant 48 bighas, a different area and price.

❓

The question

Was the agreement void, and could the earnest be forfeited?

🔨

What the court held

A mutual mistake about area, as essential as price. Void; the forfeiture clause fell and the money was refunded.

What CLAT takes from it: Area and price are essential; void means restitution.

How has CLAT asked it?

📝 Asked in CLAT 2022 · Q101 Existence of subject matter

When parties to a contract are under a ‘mistake’ regarding an important fact related to such contract, it may affect the contract in two ways. It may, firstly, defeat the consent altogether … Two or more persons are said to consent when they agree upon the same thing in the same sense. Secondly, the mistake may mislead the parties as to the purpose which they had contemplated … Thus, agreement is void when: (1) both the parties to an agreement are mistaken, (2) their mistake is as to a matter of fact, and (3) the fact about which they are mistaken is essential to the agreement … a mistake, in order to invalidate a contract, should be a mistake of fact and not a mistake of law …

Mr. A entered into an agreement to sell his bicycle, kept unused in his attic for a year, to Mr. B at an agreed price. Neither party was aware that, at the time of the agreement, the bicycle had already been destroyed by a fire in the attic. Which statement is true?

AThe agreement is void as both parties were under a mistake as to a matter of fact essential to the agreement.

BThe agreement is void as both parties were under a mistake as to a law in force in India.

CThe agreement is not voidable as only one of the parties was under a mistake as to a matter of fact.

DThe agreement is not voidable as the promise made under the agreement had not been performed.

Reveal answer + reasoning

Answer: A

Three ticks. Both unaware. The bike's existence is a fact. You can't sell ash, so it's essential. Void: Couturier v Hastie with a bicycle.

Why the others fail

B — No law is involved.
C — Neither knew; the mistake was shared.
D — Performance is irrelevant to whether it was void from the start.

📝 Asked in CLAT 2022 · Q102 Mistake of law

(Same passage.) … a mistake, in order to invalidate a contract, should be a mistake of fact and not a mistake of law …

Ms. X and Ms. Y entered into a contract of sale of an article, under the erroneous belief that its sale was permitted by the law in force in India. Which statement is true?

AThe contract is valid.

BThe contract is voidable at the option of Ms. X.

CThe contract is voidable at the option of Ms. Y.

DThe contract is not voidable.

Reveal answer + reasoning

Answer: D

Both erred, but about Indian law, which cannot invalidate a contract. Mistake gives no escape: not voidable.

Why the others fail

A — Overreaches: if the law forbids the sale, it may be void for unlawful object, a separate rule.
B — Mistake of law gives no option to cancel.
C — Same flaw as B.

📝 Asked in CLAT 2022 · Q103 Same thing, same sense

(Same passage.) … It may, firstly, defeat the consent altogether … Two or more persons are said to consent when they agree upon the same thing in the same sense. Secondly, the mistake may mislead the parties as to the purpose which they had contemplated …

Mr. J agreed with Mr. K to sell Mr. J’s ‘club’. Mr. J believed he was selling his golf club; Mr. K believed he was buying a clubhouse owned by Mr. J. The agreement is void because:

Amistake of fact defeated the consent of the parties.

Bmistake of fact misled the parties as to the purpose of the contract.

Cmistake of fact was regarding the identity of parties.

Dboth (A) and (B)

Reveal answer + reasoning

Answer: D

Golf club vs clubhouse: one word, two things, so consent was unreal (A). The key also accepts B, each man misled about what the deal was for. Strictly A fits best, but the key says D: when a passage lists two effects and the facts plausibly show both, ‘both’ is live.

Why the others fail

A — Right, but the key treats B as also met.
B — Half the key's answer.
C — Both knew who they were dealing with; the confusion was about the thing.

ℹ️ The other two 2022 questions

Q104: both thought a gift deed was a lease, a shared mistake of fact (key A). Q105: goods came by a different ship but on time; valid, fact not essential (key C).

💥 Myth vs fact

Myth vs fact

🙅 Myth

Any honest mistake lets you cancel.

Tap to bust it →

✅ Fact

Only a shared mistake of fact that is essential.

🙅 Myth

Overpaying is a mistake of fact.

Tap to bust it →

✅ Fact

A wrong opinion about value is not.

🙅 Myth

A mutual mistake makes a contract voidable.

Tap to bust it →

✅ Fact

It is void from the start; nobody holds an option.

🙅 Myth

Mistake of law is never an excuse.

Tap to bust it →

✅ Fact

True for Indian law; foreign law counts as fact.

🎯 Quick quiz

Mistake or no mistake? 5 quick checks

0 / 5

Aarav agrees to sell Zoya his grandfather's watch, which both believe is in his locker. It was stolen a week earlier.

Q1. Status of the agreement?

Zoya pays Kabir ₹50,000 for a lamp she thinks is worth ₹2 lakh. It's worth ₹5,000. Kabir said nothing about it.

Q2. Can Zoya escape for mistake?

Rohan and Kabir sign a supply deal, both wrongly believing an Indian state rule exempts the goods from a levy.

Q3. Can Kabir avoid the contract?

A passage says a mistake about foreign law counts as a mistake of fact. Aarav and Zoya contract to export spices, both wrongly believing Singapore permits their import. It doesn't.

Q4. What follows?

A rogue emails Kabir as ‘Sharma Electronics’, a known dealer, gets 20 TVs on credit and sells them to Rohan, who knows nothing. A passage says that where a seller means to deal only with a specific person and an impostor takes their place, no contract arises.

Q5. Can Kabir recover the TVs from Rohan?

Test the three ticks under the clock

Timed Contracts drills in the real exam screen.

Start a Contracts drill

🎯 In a nutshell

Void: both mistaken, about a fact, essential to the deal.
One-sided: binds, unless caused by the other side (voidable), or about identity or the document's nature.
Value: a wrong opinion never counts.
Law: Indian, no excuse; foreign, treated as fact.
Aftermath: advances go back.

📎 Good to know, not to memorise

Indian Contract Act, 1872: consent s.13; mistake of fact s.20; mistake of law s.21; unilateral mistake s.22; impossibility s.56; restitution s.65; money paid by mistake s.72.
Sale of Goods Act, 1930, s.7: specific goods already perished, unknown to the seller, make the sale void.
Phillips v Brooks (1919): face-to-face impostor, voidable. Sales Tax Officer v Kanhaiya Lal Mukundlal Saraf (SC, 1958): money paid under a mistake of law is recoverable.

Frequently asked questions

Is a contract made under a mistake void or voidable?

It depends who was mistaken. If both parties were wrong about a fact essential to the agreement, it is void from the start. If only one was, the contract binds. It is voidable only if the other side caused the mistake by fraud or misrepresentation.

What is the difference between bilateral and unilateral mistake?

Bilateral means both parties are wrong about the same essential fact, or at cross-purposes over the same words: the agreement is void. Unilateral means only one side is wrong, so the contract binds, except in narrow cases of mistaken identity or the nature of a signed document.

Why is a mistake about foreign law treated as a mistake of fact?

Everyone is presumed to know their own country's law, so a mistake about Indian law gives no escape. Nobody can be expected to know every foreign legal system, so a mistake about a foreign rule is handled like a fact. If shared and essential, the agreement is void.

Is overpaying for something a mistake of fact?

No. A wrong opinion about value is expressly not a mistake of fact. Pay ₹50,000 for a lamp worth ₹5,000 and you still bought the lamp you saw; you misjudged its worth. Unless the seller lied, the bargain stands.

How is mistake in contract different from mistake of fact in criminal law?

In contract, mistake decides whether an agreement exists. In criminal law, a good-faith mistake of fact can remove the guilty mind, as when someone honestly believes they act lawfully. Neither excuses a mistake about the law of the land.