Promissory Restitution (Material Benefit Rule)

Promissory restitution, also known as the material benefit rule, is a doctrine that makes enforceable a promise given in recognition of a benefit previously conferred on the promisor. Traditional contract doctrine holds that past consideration is not consideration — a promise made after the benefit has been received lacks the bargained-for exchange required for an enforceable contract. The material benefit rule is a recognized exception to this principle.

The Restatement (Second) of Contracts Section 86 provides the modern formulation: a promise made in recognition of a benefit previously received by the promisor is binding to the extent necessary to prevent injustice. The promise is not binding if the benefit was conferred as a gift or if the promisor was not unjustly enriched. Courts assess whether the value of the benefit was disproportionate to the promise and whether enforcement is necessary to prevent injustice.

The leading case is Webb v. McGowin, in which a worker was severely injured while saving his employer's life, and the employer subsequently promised to pay the worker a pension for life. The court enforced the promise, reasoning that the employer had received a material benefit (the saving of his life) and that his subsequent promise to pay was morally and legally binding. This result stands in contrast to Mills v. Wyman, where a father's promise to pay for care previously provided to his adult son was held unenforceable because the father had not personally received the benefit.

The doctrine is narrower than promissory estoppel, which does not require a prior benefit, and broader than traditional consideration doctrine, which would not recognize a post-benefit promise as supported by consideration. It occupies a middle ground, enforcing promises where the combination of a material benefit actually received and a subsequent express promise creates a sufficient basis for legal obligation.