Contract Law: The Doctrine of Mistake

This set covers the types, effects, and key case law regarding the doctrine of mistake in contract law, including common, mutual, and unilateral mistakes, and the plea of non est factum.

According to Amalgamated Investment & Property Ltd. v John Walker [1976], to vitiate a contract, the mistake must have existed at the __________ the contract was concluded.

time

At common law, the effect of an operative mistake is to render the contract __________.

void ab initio

In the case of Addai v PTC Ltd., Francois JSC stated that a successful plea of mistake wipes out any view of __________ and destroys the foundation of an agreement.

consensus

Unlike common law, mistake in __________ has a wider scope and can be a defense for specific performance, a ground for rectification, or rescission.

equity

A __________ mistake occurs when both contracting parties make exactly the same mistake regarding the subject matter.

common

If a common mistake only affects the __________ of the subject matter, such as in Smith v Hughes, the contract is generally not void.

quality

In Leaf v Int'l Galleries, the mistake regarding whether a painting was by the artist __________ was held to be only a mistake of quality.

Constable

For a mistake in quality to render a contract void under the rule in Bell v Lever Bros, it must make the identity of the subject matter __________ from what it was believed to be.

radically different

The term __________ refers to a common mistake where, unknown to the parties, the specific subject matter has ceased to exist at the time of the contract.

res extincta

In the case of __________, a contract for the sale of corn was void because the cargo had been sold by the ship's master before the contract was made.

Couturier v Hastie (1856)

The concept of __________ occurs when a party enters into a contract to buy property that, unknown to both parties, already belongs to the buyer.

res sua

A __________ mistake arises when parties are at cross purposes and unaware of each other's different intentions, meaning there is no consensus ad idem.

mutual

In the case of __________, the contract was void for mutual mistake because the parties were referring to two different ships with the same name sailing at different times.

Raffles v Wichelhaus

A __________ mistake occurs when only one party is mistaken and the other party knows or is deemed to know of that mistake.

unilateral

Under the principle of Boulton v Jones, a party cannot __________ an offer that was not made to them.

accept

A mistake as to __________ arises when one party intends to contract with a specific person but ends up contracting with a rogue through fraud.

identity

The legal principle __________ ("no one gives what they do not have") applies when a contract is void for mistake, meaning a rogue cannot pass title to a third party.

nemo dat quod non habet

The case of __________ established that where parties deal face-to-face (inter praesentes), there is a strong presumption that they intend to contract with the person physically present.

Phillips v Brooks Ltd

The plea of __________ (meaning "it is not my deed") is used when a person is induced by fraud to sign a document fundamentally different from what they intended.

non est factum

To successfully plead non est factum, as seen in Gallie v Lee, the signer must show they were not __________ when they signed the document.

negligent