Estoppel
Equity

An estoppel is a legal principle to prevent or bar some action by party. Essentially there are two statements that present a contradiction and result is that the earlier is taken as the truth. Therefore, estoppel precludes a person from asserting something contrary to what is implied by his or her previous action or statement or by a previous judicial determination concerning that person.

There are a number of forms of estoppel in English law and they include Estoppel by Representation, Promissory Estoppel and estoppel by convention. In respect to res judicata, there are various forms: estoppel by judgment, estoppel per rem judicatam, and estoppel by merger.