A unilateral mistake occurs when only one party in a contract is mistaken about a material fact. Here’s a simple example:
Imagine Alice is selling a painting and tells Bob that it is an original work by a famous artist, thinking it is genuine. Bob, believing Alice's claim, buys the painting for a high price. Later, Bob discovers that the painting is actually a replica and not an original work by the famous artist.
In this case:
- **Alice** made a mistake about the authenticity of the painting.
- **Bob** was unaware of Alice’s mistake and based his decision on her false statement.
Here, Alice's mistake is unilateral because only she was mistaken about the fact (the painting's authenticity), while Bob was not aware of this mistake. If Alice had known that the painting was a replica and still claimed it was original to deceive Bob, that would involve fraud, but a unilateral mistake involves just one party's incorrect belief.