Promissory estoppel
There are three exceptions to the rule in Pinnel's case. They are composite agreement, payment of debt by third party and promissory estoppel. The rule in Pinnel's case (1602) 5 CoRep117a is that part payment of debt is not good consideration to forgo the balance. Thus the creditor may sue for the remaining debt unless there is fresh consideration.
Promissory estoppel like proprietary estoppel is popular types of equitable estoppel. The importance of equitable estoppel was stated in Crabb V. Arun DC (1976) 1 Ch 179 that “equity comes in........ to mitigate the rigours of strict law.......... it prevents a person from insisting on his strict legal rights.... when it would be inequitable for him to do so having regards to the dealings which has taken place between the parties”.
An example of promissory estoppel is where A promises B that he would not enforce his legal rights and B acted and relied on it without giving any consideration, equity would not allow A to renege on his promise to B.
The modern concept of promissory estoppel was developed in the cases of Central London Property trust Ltd V. High Tree House Ltd. (1974)1 KB 130 and Total Metal Manufacturing Ltd V. Tungsten Electric Co Ltd. (1955) 1 WLR 761.
Law Essay Marking
Promissory estoppel differs from common law estoppel because it has less strict requirements and it may arise from promise of future conduct or intention. Promissory estoppel is traceable to Hughes V. Metropolitan Railway (1877)2 App Case 439. Here the landlord gave his tenant 6 months to repair the property else risk forfeiture. Within