On the Doctrine of Estoppel in Common Law

The doctrine of estoppel that stemmed from Equity Law is a very important conception and principle in Englo-American legal system.This paper expounds four types of the doctrine of estoppel,namely,estoppel in evidence law, equitable estoppel,estoppel in contract law and proprietary estoppel, and discusses their applicable conditions.This paper also shows the essence of the doctrine of estoppel that is the party's conduct of breaching his previous promise,which causes damage or loss of other party's right and interests, should be forbidden,in a short word,every party must keep his word in his bond.