Promissory estoppel is an equitable theory of recovery that permits enforcement of a promise when one or more elements necessary to create an enforceable contract are missing.
The elements of promissory estoppel are generally: (1) a promise; (2) foreseeability of reliance by the promisor; (3) substantial and reasonable reliance by the promisee to its detriment; and (4) enforcing the promise is necessary to avoid injustice.
In California, promissory estoppel serves as a legal remedy that allows a party to enforce a promise even when a formal contract does not exist or when certain elements of a contract are missing. The doctrine is based on principles of equity and fairness, aiming to prevent injustice that would result from the promisor's failure to fulfill a promise that the promisee reasonably and detrimentally relied upon. The essential elements required to establish promissory estoppel in California are: (1) a clear and unambiguous promise by the promisor; (2) reasonable and foreseeable reliance by the promisee on the promise; (3) actual and substantial reliance by the promisee, which leads to a detriment; and (4) a finding by the court that injustice can only be avoided by enforcing the promise. California courts will assess these factors on a case-by-case basis to determine whether promissory estoppel is applicable.