Question

What is the type of mistake which occurs when only one party to a contract is mistaken as to the terms or subject-matter?

(a) Mutual mistake

(b) Unilateral mistake

(c) Bilateral mistake

(d) Individual mistake

The question was posed to me in exam.

This key question is from Contract System in section P.W.D of Civil Engineering Drawing

Answer 1

The correct answer is (b) Unilateral mistake

For explanation I would say: The courts will uphold such a contract unless it was determined that the non-mistaken party was aware of the mistake and tried to take advantage of the mistake. It is also possible for a contract to be void if there was a mistake in the identity of the contracting party. An example is in Lewis v. Avery where Lord Denning MR held that the contract can only be voided if the plaintiff can show that, at the time of agreement, the plaintiff believed the other party’s identity was of vital importance. A mere mistaken belief as to the credibility of the other party is not sufficient.