Development of Promissory Estoppel

Generally, under contract law, if you promise to pay part of a debt and your creditor agrees to release you from the obligation to pay the rest, courts will not enforce this agreement, if there is not further "consideration" (payment or some other quid pro quo). Promissory estoppel , an exception to this rule, is a legal doctrine that says if someone makes a promise and someone else relies on it to their detriment, the promise is legally enforceable (the promisor is stopped, or estopped, from going back on the promise).

Common Law Estoppel

Common law estoppel is similar to promissory estoppel except that its requirements are stricter and it does not arise from a promise of future conduct.

Nineteenth Century

The need for flexibility in contracts in long-term business relationships ran square into the inflexibility of contract law as it existed at the time. Theory lagged behind practice as courts sometimes enforced promises that weren't part of the original agreement, though they failed to give clear explanations why they were doing it.

Williston and the Restatement

Samuel Williston was a strong advocate of promissory estoppel and he fought successfully to have it included in 1932 in the influential "Restatement of Contracts," a legal text. Joel M. Ngugi, a University of Washington law professor, now calls the doctrine "influential" and "successful."

References

• Law Teacher: Part Payment of Debts.
• Bnet: Origins of Promissory Estoppel.
• University of Richmond Law Review; Promissory Estoppel: The Life History of an Ideal Legal Transplant; Joel M. Ngugi; January 2007.

Resources

• Am. Bus. Law Jrnl.; Promissory Estoppel ...; Michael B. Metzger, Michael J. Phillips; Oct. 9 2008.