Estoppel

A legal doctrine that prevents an insurance carrier from denying coverage or asserting a policy defense when its prior conduct led the insured to reasonably rely on the existence of coverage. In the law firm insurance context, estoppel may arise when a carrier accepts premiums, issues a binder, or defends a claim without issuing a timely reservation of rights, then later attempts to disclaim coverage. Courts apply estoppel to prevent insurers from taking inconsistent positions that prejudice the insured firm. The doctrine varies significantly by state and is not universally available as a coverage remedy.