Restatement Second of Contracts § 86
- A promise made in recognition of a benefit previously received by the promisor from the promisee is binding to the extent necessary to prevent injustice.
- A promise is not binding under Subsection (1)
- if the promisee conferred the benefit as a gift or for other reasons the promisor has not been unjustly enriched; or
- to the extent that its value is disproportionate to the benefit.