What is the legal principle that prevents an individual from asserting something contrary to prior words or deeds?

Estoppel is the legal principle that prevents an individual from asserting something contrary to their prior statements or actions. This concept is grounded in the idea of fairness and the protection of parties who have relied on those prior representations.

When someone makes a representation or commitment, whether through words or conduct, and another person relies on that representation to their detriment, the first person can be "stopped" from changing their position later on. This principle upholds the integrity of dealings and promotes trust in legal and business transactions.

For example, if a property owner verbally agrees to sell their home to a buyer and the buyer takes steps based on that agreement (like expending money on inspections), the seller may be estopped from later saying they are not selling the property—because the buyer has reasonably relied on the seller's original commitment.

Other options like forfeiture, reformation, and liability address different legal concepts. Forfeiture involves losing a right or property due to a failure to fulfill a legal obligation, reformation refers to changing the terms of a contract to reflect what the parties actually intended, and liability generally relates to being legally responsible for an action or omission. None of these directly relate to the principle of preventing contradictory claims based on prior conduct or declarations