Adversary System

Definition of Adversary System

Note: See a more comprehensive approach to the Adversary System legal concept in the American Law Encyclopedia

A set of processes intended to allow opposing parties in a dispute to present their arguments. Under the adversary system, formal notice is served on the party against whom an action has been filed to allow that party an opportunity to respond. The adversary system is typically self-initiated although the prosecuting attorney acts on behalf of the victim and the public in criminal matters. The burden of proof falls to the parties under the adversary system. Most often, the judge's role is to preside over the proceeding rather than function as an actual fact-finder. The outcome in an adversary proceeding is almost always all or nothing, and, unlike mediation or conciliation, is zero-sum in character. That means there is seldom a middle-ground outcome, and whatever the successful party wins is necessarily lost by the unsuccessful party. The outcome of such proceedings is authoritative; it is enforced upon the losing party. An adversary proceeding is different from an ex parte proceeding, where only one party appears. An adversary proceeding also differs from a summary proceeding, where no significant fact dispute exists and where the court may hasten and simplify the resolution of an issue.

Commentary on Adversary System

“The term adversary system sometimes characterizes an entire legal process, and sometimes it refers only to criminal procedure. In the latter instance, it is often used interchangeably with an old expression of continental European origin, 'accusatorial procedure,' and is juxtaposed to the 'inquisitorial,' or 'no adversary,' process. There is no precise understanding, however, of the insti? tutions and arrangements denoted by these expressions.” Mirjan Damaska, “Adversary Procedure,” in 1 Encyclopedia of Crime and Justice 24, 24-25 (Sanford H. Kadish ed., 1983).

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