- Unilateral mistake: there is some mistake or misunderstanding in the communications between the parties which prevents there being an effective agreement, for instance, one party in an offer states terms which the other party knows the first party does not intend. Only one of the parties is mistaken. The other knows or must be taken to know, of his mistake.
- Mutual mistake: the parties misunderstand each other and are at cross purposes.
- Common mistake: both parties make the same mistake. Each knows the intention of the other and accepts it, but each is mistaken about some underlying and fundamental fact. The parties, e.g. are unaware that the subject matter of their contract has already perished
- Mutual mistake
- Unilateral mistake
The relevant provisions under the CA are S. 21, S.22, and S.23
- S 21: an agreement is void if both the parties to the agreement are under a mistake as to a matter of fact essential to the agreement
- S 23: a mistake caused by one of the parties to an agreement does not render the contract void.
- S. 22: a contact is not voidable because it was caused by a mistake as to any law in force in Malaysia, but a mistake as to any law not in force in Malaysia has the same effect as a mistake of fact
- S 21 covers both mutual and common mistakes
- only a few reported cases where the scope of S.21 has been considered by the Malaysian courts.
- it would appear that the basis for rendering agreements void under S.21 is that, in such situations, either there had been no free consent between the parties, or the consent was nullified (CR S.14(e) ).
- For a mistake to be operative under S.21, it must be one ‘essential to the agreement.’ The circumstances under which a fact may be regarded as ‘essential to an agreement’ are not made clear by the Act.

