What does the concept of estoppel protect?

Estoppel serves to protect parties from changing positions based on prior actions or representations. This legal doctrine is important because it promotes fairness and consistency by preventing a party from asserting a claim or a fact that contradicts their previous conduct, which another party has relied upon. For example, if one party has made a representation or acted in a way that leads another party to believe something to be true, they cannot later claim something contrary to that belief if the other party has acted based on that initial representation. This principle upholds the integrity of agreements and interactions, ensuring that parties act in good faith and can rely on each other's statements and actions.

In contrast, the other options do not accurately capture the essence of estoppel. Changing contract terms at any time does not relate to the concept of estoppel; rather, estoppel is about adherence to previously established positions. Likewise, while vague terms can lead to disputes, estoppel does not directly address their enforceability. Finally, the concept of coercion or duress pertains to whether a contract is valid, which is separate from the idea of estoppel regarding prior conduct and reliance by the parties involved.