Contract disputes sometimes arise when one party enters into an agreement based on a significant mistake that the other party does not share. Unlike a mutual mistake, a unilateral mistake involves an error made by only one side of the transaction.
Under California law, a unilateral mistake does not automatically allow a party to avoid a contract. Courts may examine the nature of the mistake, its effect on the agreement, the conduct of the other party, and the consequences of enforcing or rescinding the contract.
How Courts Identify the Mistake
Courts may first examine what the mistaken party believed when entering into the agreement and how that belief differed from the actual circumstances. The mistake generally must concern a matter that significantly affected the transaction.
The source and nature of the error can also become relevant. Courts may distinguish a substantial mistake affecting the agreement from a minor miscalculation or unfavorable assumption that does not materially alter the transaction.
How the Other Party’s Knowledge Matters
A unilateral mistake can receive greater scrutiny when the other party knew or had reason to know that a significant error had occurred. The circumstances surrounding negotiations and formation of the agreement may therefore become important.
Courts may examine communications, documents, pricing, and other information available when the contract was formed. These circumstances can help determine whether the nonmistaken party recognized or should have recognized the error.
How the Mistake Affected the Agreement
Courts may consider whether the mistake had a substantial effect on the exchange contemplated by the parties. An error involving an important price, quantity, obligation, or other contractual matter may have greater significance than an incidental mistake.
The analysis can include what the agreement would require if enforced according to its written terms. Courts may consider the relationship between the mistake and the obligations the mistaken party would otherwise be required to perform.
How Courts Examine the Mistaken Party’s Conduct
The circumstances that produced the mistake can also become relevant. Courts may examine whether the error resulted from ordinary inadvertence or from conduct that involved a more serious failure to exercise reasonable care.
A party’s responsibility for an error does not necessarily resolve the entire dispute by itself. The surrounding circumstances, including the conduct of both parties and the effect of the mistake, can influence how the issue is evaluated.
How Rescission Can Become Relevant
A party affected by a unilateral mistake may seek rescission in circumstances recognized by California law. Rescission is intended to extinguish the contract rather than simply change an unfavorable contractual term.
When rescission is sought, additional issues may involve notice and the restoration of benefits received under the agreement. Courts may therefore consider both the underlying mistake and the steps taken after the mistake was discovered.
Why Unilateral Mistake Matters
Unilateral mistake disputes demonstrate that an error by one contracting party does not necessarily have the same consequences as a mistake shared by both sides. The specific circumstances surrounding formation and performance can become important.
These cases may involve the significance of the error, the other party’s knowledge, the parties’ conduct, and the consequences of enforcing the agreement. Examining those factors helps courts determine the legal effect of a mistake made by only one party.
