Effect of unilateral mistake at common law
- When the mistake of X is known to Y
- Unilateral mistake is void at common law
- Actual knowledge is required to find a unilateral mistake at common law
Effect of unilateral mistake in equity
- On the other hand, the taking advantage of another’s mistake in the procuring of an agreement is more clearly a basis of the equitable jurisdiction to set aside contracts for unilateral mistakes.
- The jurisdiction of equity to deal with unconscionable behaviour is a long-standing one.
- An early eminent writer, Joseph Story, stated:
The fact may be unknown to both parties, or it may be known to one party and unknown to the other. If it is known to one party, and unknown to the other, that will in some cases afford a solid ground for relief, as for instance where it operates as a surprise, or a fraud, upon the ignorant party. But in all such cases the ground of relief is, not the mistake or ignorance of material facts alone, but the unconscientious advantage taken of the party by the concealment of them. For if the parties act fairly, and it is not a case where one is bound to communicate the facts to the other, upon the ground of confidence, or otherwise, there the court will not interfere.
Chwee Kin Keong v. Digilandmall.com Pte. Ltd. (2005)
- Appellants communicated the price of the printers to his friends, they knew that it might be a mistake; from the evidence they suspected there was a mistake in the pricing!
- And the price was exceedingly low at $66 compared to the $3000 over bucks for the actual printer.
- They bought in bulk and together were the biggest purchasers
- When respondents discovered their mistake, they told appellants that they were not honour the orders
- Appellants instituted proceedings to enforce the contract
- Trial judge found that appellants had actual or constructive knowledge of the mistake in...