A **unilateral mistake** occurs when only one party in a contract is mistaken about a material fact or term, while the other party is aware of the mistake but does not correct it. This can sometimes lead to the contract being voidable, depending on the situation.
### Example:
Imagine you are selling a rare painting online. You mistakenly list the price as $100, thinking it's a small replica. A buyer sees the listing and immediately agrees to purchase it for that price, not knowing that you made a mistake.
In this case, you, as the seller, are the one making the unilateral mistake. The buyer isn't mistaken about the price—they simply took advantage of your error. The seller might have a right to cancel or correct the contract, depending on the legal circumstances, because of the mistake made by one party.
In some situations, the contract could still be enforced if the mistake was not obvious to the buyer, or if the other party acted in good faith. However, the buyer might also argue that they should be entitled to the item at the mistaken price.
So, a unilateral mistake typically involves one party being unaware of a misrepresentation, and the other party knowing or not correcting the error.