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 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 generally 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 plaintiff(s) from its duty of presenting a case to the trial court.
These are pleas which claim that a case cannot proceed for some reason. They are so called because, rather than being an answer to the question of guilt or innocence, they are a claim that the matter of guilt or innocence should not be considered.
They are :
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.
In United States v. Binion, malingering or feigning illness during a competency evaluation was held to be obstruction of justice and led to an enhanced sentence. Although the defendant had pled guilty, he was not awarded a reduction in sentence because the feigned illness was considered to mean that he was not accepting responsibility for his illegal behavior.