Inquisitorial System

An inquisitorial system is a legal system where the court or a part of the court is actively involved in investigating the facts of the case, as opposed to an adversarial system where the role of the court is primarily that of an impartial referee between the prosecution and the defense. Inquisitorial systems are used in some countries with civil legal systems as opposed to common law systems. Also countries using common law, including the United States, may use an inquisitorial system for summary hearings in the case of misdemeanors such as minor traffic violations. In fact, the distinction between an adversarial and inquisitorial system is theoretically unrelated to the distinction between a civil legal and common law system. Some legal scholars consider "inquisitorial" misleading, and prefer the word "nonadversarial". The function is often vested in the office of public procurator, as in many communist or ex-communist states such as Russia, China, and Ukraine, in addition to non-communist jurisdictions such as Japan and Scotland.

The inquisitorial system applies to questions of criminal procedure as opposed to questions of substantive law; that is, it determines how criminal enquiries and trials are conducted, not the kind of crimes for which one can be prosecuted, nor the sentences that they carry. It is most readily used in some civil legal systems. However, some jurists do not recognize this dichotomy and see procedure and substantive legal relationships as being interconnected and part of a theory of justice as applied differently in various legal cultures.

In some jurisdictions, the trial judge may participate in the fact-finding inquiry by questioning witnesses even in adversarial proceedings. The rules of admissibility of evidence may also allow the judge to act more like an inquisitor than an arbiter of justice.