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 "accusatorial procedure," and is juxtaposed to the "inquisitorial," or "non-adversary," process. There is no precise understanding, however, of the institutions and arrangements denoted by these expressions.

Nevertheless, several characteristics are commonly associated by American lawyers with the adversary criminal process. These include a relatively passive tribunal that ideally comprises both judge and jury; the presentation of evidence by the parties through their lawyers, who proceed by direct questioning and cross-examination of witnesses; the representation of state interests by one of the parties, the prosecutor; a presumption that the defendant is innocent until proved guilty; and the principle that he cannot be forced to testify against himself. The contours of the adversary system remain uncertain because the phrase has been used to describe three distinctive, albeit related, meanings.