This chapter explains how contractual duties may be altered or discharged through later agreement, good-faith modification, or substitute performance. The strategic recalibration in The Black Gate offers a fitting parallel to the law’s treatment of changed plans under changed conditions.
Doctrinal map
Common law applies the pre-existing-duty rule: a promise to pay more for the same performance is unenforceable (Alaska Packers v. Domenico). The Restatement softens the rule in R2d § 89: modifications without new consideration are enforceable where made before full performance, fair and equitable, and prompted by unanticipated circumstances (Angel v. Murray). The UCC drops the consideration requirement entirely and imposes a good-faith standard (§ 2-209).
Key Sources
Key Rules
- R2d § 89: Modification without consideration may be enforceable if fair and equitable
- UCC § 2-209: Good faith modification without consideration
- Accord and satisfaction: substitute agreement
Cases
- Alaska Packers' Association v. Domenico 117 F. 99 (9th Cir. 1902) A modification of an existing contract demanding additional compensation for the same performance is unenforceable for lack of consideration (pre-existing duty rule) and, where coerced by the obligor's leverage over a counterparty with no realistic alternative, is also voidable as the product of duress.
- Angel v. Murray 113 R.I. 482, 322 A.2d 630 (1974) A modification of an executory contract is enforceable without new consideration where (1) the modification was made before performance was complete on either side, (2) the parties voluntarily agreed, (3) the modification is fair and equitable in view of unanticipated circumstances, and (4) it does not run against statute or public policy. (Restatement (Second) § 89.)