Final answer:
The consideration rule for contract modification under common law is the pre-existing duty rule, which states that if a party is already obligated to perform a duty, doing so does not constitute valid consideration for a contract modification. Article 2 of the UCC provides a more flexible approach to contract modification without the need for additional consideration if both parties act in good faith.
Step-by-step explanation:
The consideration rule for contract modification under common law differs from Article 2. Under common law, there is a legal principle called the 'pre-existing duty rule', which states that if a party is already obligated to perform a duty, doing so does not constitute valid consideration for a contract modification. This means that if one party is already legally obligated to do something, such as providing goods or services under the original contract, they cannot demand additional consideration for a modification.
For example, let's say Party A and Party B enter into a contract for Party A to build a house for $100,000. Midway through the construction, Party A encounters unexpected difficulties but is still required to complete the project. Under the common law pre-existing duty rule, Party A cannot demand additional payment for overcoming these difficulties since they were already obligated to complete the project for the agreed-upon price.
On the other hand, Article 2 of the Uniform Commercial Code (UCC) provides a more flexible approach to contract modification. Article 2 recognizes that commercial transactions often require modifications due to changing circumstances. It allows modification without the need for additional consideration if both parties act in good faith. This means that as long as the modification is fair and reasonable and there is no evidence of bad faith or unfair dealing, the modification will be enforceable.