The adversarial system or adversary system is a legal system used in the common law countries.[1] It is a system where two advocates represent their parties' positions before an impartial person or group of people.[2] This is usually a jury or judge who attempt to determine the truth of the case.[3] 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). This is where a judge or group of judges opens an official inquiry and decides the case.[4]
The adversarial system is the two-part system under which criminal law courts operate.[5] On one side is the prosecution who usually represents the government. The other side is the defense who represents the defendant. Each party may call witnesses and ask questions.[5] Each party may present evidence based on legal ethics and that is approved by the court.[6] For example, legal ethics prevent a lawyer from calling a witness they know will lie on the witness stand.[6] Justice is served when the most effective adversary is able to convince the jury or judge that his or her case is the correct one.[5]