There are two major systems of criminal procedure in the modern world—the adversarial and the inquisitorial. Both systems were historically preceded by the system of private vengeance in which the victim of a crime fashioned a remedy and administered it privately, either personally or through an agent.
The modern adversarial system is only one historical step removed from the private vengeance system and still retains some of its characteristic features. For example, even though the right to initiate legal action against a criminal has now been extended to all members of society (as represented by the office of the public prosecutor), and even though the police department has effectively assumed the pretrial investigative functions on behalf of the prosecution, the adversarial system still leaves the defendant to conduct his or her own pretrial investigation. The trial is viewed as a forensic duel between two adversaries, presided over by a judge who, at the start, has no knowledge of the investigative background of the case. In the final analysis the adversarial system of criminal procedure symbolizes and regularizes punitive combat.
By contrast, the inquisitorial system begins historically where the adversarial system stopped its development. It is two historical steps removed from the system of private vengeance. From the standpoint of legal anthropology, then, it is historically superior to the adversarial system. Under the inquisitorial system, the public prosecutor has the duty to investigate not just on behalf of society but also on behalf of the defendant. Additionally, the public prosecutor has the duty to present the court not only evidence that would convict the defendant, but also evidence that could prove the defendant’s innocence. The system mandates that both parties permit full pretrial discovery of the evidence in their possession. Finally, an aspect of the system that makes the trial less like a duel between two adversarial parties is that the inquisitorial system mandates that the judge take an active part in the conduct of the trial, with a role that is both directive and protective.
Fact-finding is at the heart of the inquisitorial system. This system operates on the philosophical premise that in a criminal action the crucial factor is the body of facts, not the legal rule (in contrast to the adversarial system), and the goal of the entire procedure is to attempt to recreate, in the mind of the court, the commission of the alleged crime.
Because of the inquisitorial system’s thoroughness in conducting its pretrial investigation, it can be concluded that, if given the choice, a defendant who is innocent would prefer to be tried under the inquisitorial system, whereas a defendant who is guilty would prefer to be tried under the adversarial system