In countries adopting the common law adversarial system or the civil law inquisitorial system, the prosecutor is the chief legal representative of the prosecution. The prosecution is the legal party responsible for presenting the case against an individual suspected of breaking the law in a criminal trial.

Common law countries

Prosecutors are typically lawyers who possess a university degree in law, are recognized as legal professionals by the court in which they intend to represent the state, and, in countries where the distinction is made, are barristers. They usually only become involved in a criminal case once charges need to be laid. They are typically employed by an office of the government with safeguards in place to ensure such an office can successfully pursue the prosecution of government officials. Often multiple offices exist in a single country due to the various legal jurisdictions that exist.

In the United Kingdom, Australia and Canada the director of any such office is typically known as the Director of Public Prosecutions and is appointed (as opposed to elected).

In the United States the director of any such offices may be known by any of several names depending on the legal jurisdiction (e.g. County Attorney, County Prosecutor, State Attorney, State Prosecutor, District Attorney or U.S. Attorney) and may be either appointed or elected.

Because they are backed by the power of the state, prosecutors are usually subject to special professional responsibility rules in addition to those binding all lawyers as a whole. For example, as "ministers of justice," American prosecutors are supposed to act in good faith, and can be disbarred for deliberately hiding evidence that completely exonerates the defendant.

Civil law countries

Prosecutors are typically civil servants who possess a university degree in law and additional training in the administration of justice. In some countries, such as France, they belong to the same corps of civil servants as the judges.

In France, the prosecutor, or procureur (or procureur général in a Appeal Court or the Court of Cassation) is assisted by deputies (substituts). He opens preliminary enquiries , and if necessary asks for the nomination of an investigating magistrate to lead a judiciary information . The prosecutor does not lead the enquiries himself. During a criminal trial , the prosecutor has to lay the case in front of the Court (judges or jury). He generally suggests a certain sentence, which the court has no obligation to follow — the court may decide on a higher or lower sentence. The procureur has also some other duties regarding more generally the administration of justice.