An adverse party is an opposing party in a lawsuit under an adversary system of law. In general, an adverse party is a party against whom judgment is sought or "a party interested in sustaining a judgment or decree."[1] For example, the adverse party for a defendant is the plaintiff.[2]
A witness called on behalf of an adverse party is usually an adverse witness.[3] In general, the examination of an adverse party's witness may include leading questions and follows the rules of cross examination.[4]