In legal terminology, a plea is simply an answer to a claim made by someone in a civil or criminal case under common law using the adversary system. Colloquially, a plea has come to mean the assertion by a criminal defendant, at arraignment or otherwise in response to a criminal charge, whether he is guilty or not guilty.

The concept of the plea is one of the major differences between criminal procedure under common law and procedure under the civil law system. Under common law, a plea of guilty by the defendant waives jury trial of the charged offenses and the defendant may be sentenced immediately. This produces a system under American law known as plea bargaining.

In civil law jurisdictions, there is no concept of a plea of guilty. 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 relieve the prosecution from its duty of presenting a case to the trial court.

United States

A defendant who pleads guilty must do so, in the phraseology of a 1938 Supreme Court case, "knowingly, voluntarily and intelligently". The burden is on the prosecution to prove that all waivers of the defendant's rights complied with due process standards. Accordingly, in cases of all but the most minor offenses, the court or the prosecution (depending upon local custom and the presiding judge's preference) will ask the defendant a series of rote questions about the defendant's knowledge of his rights and the voluntariness of the plea. Typically the hearing on the guilty plea is transcribed by a court reporter and the transcript is made a part of the permanent record of the case in order to preserve the conviction's validity from being challenged at some future time.

Other special pleas used in criminal cases include the plea of mental incompetence, challenging the jurisdiction of the court over the defendant's person, the plea in bar, attacking the jurisdiction of the court over the crime charged, and the plea in abatement, which is used to address procedural errors in bringing the charges against the defendant, not apparent on the "face" of the indictment or other charging instrument. Special pleas in federal criminal cases have been abolished, and defenses formerly raised by special plea are now raised by motion to dismiss.

See also

• Criminal defenses