What legal doctrine allows an action or practice of the insured party to continue due to the waiver of the insurer's defense?

The legal doctrine that allows an action or practice of the insured party to continue due to the waiver of the insurer's defense is known as estoppel. Estoppel prevents an insurer from asserting a defense that it has previously waived or from denying something that it has previously established by its conduct or statements. In cases where an insurer does not timely assert a defense, or if it acts in a way that suggests it is accepting a claim (such as paying a claim without formally denying it), it may be estopped from later trying to deny coverage or seek other defenses against the insured party. This doctrine is rooted in fairness and the principles of protecting the reasonable expectations of the parties involved, ensuring that one party does not act in a manner that leads the other party to believe they are in compliance with the terms of the contract.