Estoppel

Estoppel is a legal doctrine that bars a person from asserting a position inconsistent with one previously adopted when another party relied on it. Its forms differ in the conduct required and the legal effect.

Reliance: Dependence on a statement, promise, or course of conduct when deciding how to act. A party’s reliance on another’s position is central to many forms of estoppel.
Promissory estoppel: A doctrine that can make a promise enforceable when reasonable reliance on it makes nonenforcement unjust. It addresses reliance on promises, even when ordinary contract requirements are unmet.
Res judicata: A doctrine that bars relitigation of a claim resolved by a final judgment. It bars repeated claims based on final judgments, rather than relying on inconsistent conduct alone.
Property law: The body of law governing ownership, possession, and use of property. Reliance on a landowner’s assurance can affect whether a later property claim is allowed.
Representation: A statement or conduct conveying a fact, intention, or legal position to another person. Some estoppels begin with a representation that another party treats as true.
Equitable estoppel: A doctrine that prevents a party from contradicting a representation when another reasonably relied on it to their detriment. It is a common form of estoppel based on misleading conduct and detrimental reliance.
Issue preclusion: A doctrine that prevents relitigation of an issue actually decided in a prior proceeding. It is narrower and more rule-bound than estoppel based on representations or promises.
Contract law: The body of law governing agreements and the obligations they create. Promissory estoppel can address reliance where contract formation or consideration is disputed.
Legal right: An entitlement recognized and enforceable under law. Estoppel can restrict how a party exercises or asserts an otherwise available right.
Judicial estoppel: A doctrine that can prevent a party from taking a position in court inconsistent with one successfully asserted earlier. It protects courts from parties changing positions across proceedings.

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Common-law marriageRelated: Estoppel may affect disputes when one partner previously represented that a marriage existed.