Legal Definitions - preexisting-duty rule

The preexisting-duty rule is a legal principle that applies to contracts. It states that if a party is already legally obligated to do something or refrain from doing something, then doing or refraining from that action cannot be considered as consideration for a new promise.

For example, if a builder agrees to construct a building for a specified price but later demands more money to complete the job, the owner's promise to pay the additional amount is not enforceable because the builder is already legally obligated to complete the construction for the agreed-upon price. The builder is not providing any new consideration for the owner's promise.

The preexisting-duty rule ensures that parties cannot use threats or coercion to extract additional benefits from a contract that they are already obligated to fulfill. It promotes fairness and prevents parties from taking advantage of each other.