Adversarial system

The adversarial system or adversary system is a legal system used in the common law countries where two advocates represent their parties' case or position before an impartial person or group of people, usually a jury or judge, who attempt to determine the truth and pass judgment accordingly. It is in contrast to the inquisitorial system used in some civil law systems (i.e. those deriving from Roman law or the Napoleonic code) where a judge investigates the case.

The adversarial system is the two-sided structure under which criminal trial courts operate that pits the prosecution against the defense.

Some writers trace the process to the medieval mode of trial by combat, in which some litigants, notably women, were allowed a champion to represent them. The use of the jury in the common law system seems to have fostered the adversarial system and provides the opportunity for both sides to argue their point of view.

As an accused is not compelled to give evidence in a criminal adversarial proceeding, they may not be questioned by a prosecutor or judge unless they choose to do so. However, should they decide to testify, they are subject to cross-examination and could be found guilty of perjury. As the election to maintain an accused person's right to silence prevents any examination or cross-examination of that person's position, it follows that the decision of counsel as to what evidence will be called is a crucial tactic in any case in the adversarial system and hence it might be said that it is a lawyer's manipulation of the truth. Certainly, it requires the skills of counsel on both sides to be fairly equally pitted and subjected to an impartial judge.

By contrast, while defendants in most civil law systems can be compelled to give a statement, this statement is not subject to cross-examination by the prosecutor and not given under oath. This allows the defendant to explain his side of the case without being subject to cross-examination by a skilled opposition. However, this is mainly because it is not the prosecutor but the judges who question the defendant. The concept of "cross"-examination is entirely due to adversarial structure of the common law.

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