We may categories estoppels as follows:
1. Estoppel by Record:
It refers to judgment or public records, which are believed to be true. A person who acts in pursuance of judgment or records cannot be estopped.
2. Estoppel by Deed:
It means stopped by an agreement .When a person enters into an agreement and his/her statement is furnished their in , he/she shall not be permitted to deny his/her statement.
3. Estoppel by Conduct (Estoppel in Pais):
When a person , by acts or words or deeds induces another person to believe the existence of the thing and make him/her to act upon it, he/she is stopped from denying the existence of such facts.
4. Promissory Estoppel:
The rule of “Promissory Estoppel” is recognized by the court of equity in England. It is also known as ‘Requisite Estoppel ‘ or ‘New Estoppel.’ It does not come within the meaning of sec.34 of Evidence Act 2031.It relates with future promise , where a person makes a promise to another thereby induces him/her to do an act to alter his/her position; the person promise is stopped from denying the truth of that promise. In the case of M.P.Sugar Mills vs. State of UP,Indian Supreme Court has Evolved the concept of promissory estoppels in the first time in India.
Estoppel is rule of civil actions. It has no application in criminal proceedings and also does not operate in the question of law, which is where there is law everybody should act as per the law. Ple of estoppel does not count in such situation but admission has close relevance with estoppel. Estoppel is not a piece of evidence rather it is a procedure to stop the other party making contradictions. It is one of the important procedures, which has vital effect in any court proceedings.