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International Legal Systems - Page 2

This section of the brochure contains some very broad generalizations about the types of legal systems, but they are not specific to a country. DOJ/OVT can help you to identify the type of legal system present in the country where the prosecution is taking place. For more specific country information, please contact DOJ/ OVT.

Common Law Legal Systems

General principles:

  • The laws governing a case are based on both legal precedent, created by judges, and statutory laws, created by legislatures;
  • Usually an adversarial system, where the judge acts as an impartial referee between opposing parties to a case;
  • A jury may determine the facts , and a judge will decide the law to be applied;
  • There is an active role for prosecutors and defense attorneys;
  • Victims have a role as witnesses and may have rights as a victim to receive information and limited participation – however, victims are not a party in criminal cases;
  • The U.S. and the U.K. are examples of common law systems.


Common law was originally developed by judges through case-by-case court decisions, rather than through legislation enacted by a legislature. In this system, much of the law is made by judges’ decisions, called precedent. This means that if a similar case has been resolved by a court in the past, a court is bound to follow the reasoning used in the prior decision. While judges are very important in common law systems, legislatures still have a part to play. Common law systems also rely on statutes that are passed by the legislature or a parliament, and judges have the role of interpreting how the legislature’s laws are applied in individual cases.

In common law legal systems, legal proceedings are mostly adversarial, rather than inquisitorial. This means that for the most part, two opposing parties (adversaries) appear before a judge who moderates. Defendants are entitled to be present and to be represented by a lawyer. The attorneys on both sides generally have an active role in representing their clients throughout the case and in presenting evidence and arguments in court. A jury of people without legal training can decide the facts of the case, and if there is a conviction, then a judge determines the appropriate sentence based on the jury’s verdict.

Key Justice Participants in a Common Law System

Police: Under common law, police officers have significant independent investigative powers, including investigation of a crime, with only indirect oversight from a judge. Police must get warrants from a judge, but the police are responsible for collecting and securing all evidence.

Prosecutor: The prosecutor is responsible for filing criminal charges against the perpetrator if there is sufficient evidence to proceed to trial, and plays a very active role in presenting the prosecution evidence at trial. The prosecutor represents the government, not the victims directly. In many common law systems, the prosecutor has broad discretion as to whether to file charges, which charges to file, and how to present the case.

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Updated May 25, 2023