The concept of the plea is one of the major differences between criminal procedure under common law and procedure under civil law. Under common law, a plea of guilty by the defendant causes a jury trial to be waived and the criminal process to proceed to sentencing. This produces a system under American law known as plea bargaining.
Under civil law, there is no concept of a plea. A confession by the defendant is treated like any other piece of evidence, and a full confession does not prevent a full trial from occurring or absolve the prosecution from presenting a case.