英美法上 約束的 禁反言의 法理

Promissory estoppel is based on a goal to do justice. But it, in its current form, can not provide sufficient context to deal with social justice, justice in private business dealings, remedial justice, or something else. To make it a more workable and effective doctrine, it should be reigned in and analyzed in terms of contractual promise and more traditional estoppel principles. The promise should be enforced as a contractual promise when the promise can fairly be treated as a kind of offer and the reliance as a kind of acceptance and as some evidence of the consideration for the contract. Estoppel should be the basis for the enforcement only when appropriate under traditional principles, with the only adjustment being that the statement that invites reliance can be a promissory statement. The enforcement, then, is defined by equitable principles, including the nature and extent of the reliance. However, using promissory estoppel to enforce might violates freedom of contract. Because indefinite promises and illusory promises is often quite difficult to draw; and, like illusory promises, indefinite promises have traditionally been regarded as improper subjects for the ministrations of the reliance principle. In addition, this doctrine should be defensively used as a "shield" to estop promisor from asserting revocation of his promise. I expect that comprehension of promissory estoppel would be a way to understand estoppel doctrine in our Civil Law.