Duhaime's Law Dictionary

Equitable Estoppel Definition:

A bar to a party from asserting a legal claim or defense that is contrary or inconsistent with his or her prior action of conduct.

Related Terms: Estoppel, Equity, Promissory Estoppel, Clean Hands

Also known as estoppel en pais.

Lord Alfred Denning, in the 1951 decision of Combe v Combe, wrote:

"The principle, as I understand it, is that where one party has, by his words or conduct, made to the other a promise or assurance which was intended to affect the legal relations between them and to be acted on accordingly, then once the other party has taken him at his word and acted on it, the one who gave the promise or assurance cannot afterwards be allowed to revert to the previous legal relations as if no such promise or assurance had been made by him, but he must accept their legal relations subject to the qualification which he himself has has introduced, even though it is not supported in point of law by any consideration, but only by his word."

In Parker v Sager (1949), Chief Justice Stevens of the United States Court of Appeals, District of Columbia Circuit wrote: 

"The essential elements of equitable estoppel as related to the party estopped are: (1) Conduct which amounts to a false representation or concealment of material facts, or, at least, which is calculated to convey the impression that the facts are otherwise than, and inconsistent with, those which the party subsequently attempts to assert; (2) intention, or at least expectation, that such conduct shall be acted upon by the other party; (3) knowledge, actual or constructive, of the real facts.

"As related to the party claiming the estoppel, they are: (1) Lack of knowledge and of the means of knowledge of the truth as to the facts in question; (2) reliance upon the conduct of the party estopped; and (3) action based thereon of such a character as to change his position prejudicially."

The 2d Edition of American Jurisprudence (Volume 28, 2011), proposes this definition:

"Equitable estoppel is a judicial remedy by which a party may be precluded by its own act or omission from asserting a right to which it otherwise would have been entitled or from pleading or proving an otherwise important fact.

"It is the principle by which a party is precluded from denying any material fact, induced by his or her words or conduct upon which a person relied, whereby the person changed his or her position in such a way that injury would be suffered if such denial or assertion was allowed....

"In its broadest sense, equitable estoppel is a means of preventing a party from asserting a legal claim or defense that is contrary or inconsistent with his or her prior action of conduct."

Justice Frappier of the Quebec Superior Court adopted this definition of equitable estoppel in Gaz Métropolitain inc. c. Bacon America :

"The doctrine by which a person may be precluded by his act or conduct, or silence when it is his duty to speak, from asserting a right which he otherwise would have had.

"The doctrine rests upon principle that when a person by his acts causes another to change his condition to his detriment, person performing such acts is precluded from asserting a right which he otherwise might have had.

In the 1866 English case, Ramsden v. Dyson, Justicer Cranworth gave the example of A. who builds on land which he thinks is his, but is really B.'s and B. knowing of A.'s mistake, encourages A. to build either directly or by abstaining from asserting his legal right. In such a case equity will intervene for the protection of A.

In Fournogerakis v. Barlow, Justice Lowry opined this intriguing suggestion of law:

"Where it applies, res judicata serves as an equitable estoppel. Its purpose is to ensure justice is done, prevent abuse of process, and fulfill the societal interest of finalizing litigation. The court retains a discretion to refuse to apply the principle where in special circumstances a rigid application would frustrate its purpose."


  • Combe v. Combe, [1951] 1 All E.R. 767, at p. 770
  • Fournogerakis v. Barlow, 2008 BCCA 223
  • Gaz Métropolitain inc. c. Bacon America inc., [2001] J.Q. 6154
  • Parker v. Sager, 174 F. 2d 657
  • Ramsden v. Dyson, [1866] L.R. 1 H.L. 129. Cited with approval in R. v. Canadian Pacific Railway, [1931] A.C. 414

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