A more thorough explanation:

A special plea in bar is a type of legal defense that seeks to completely and permanently defeat the plaintiff's or prosecutor's action. It is different from a general plea in bar, which is a criminal defendant's plea of not guilty that denies every fact and circumstance necessary to be convicted of the crime charged.

A special plea in bar, on the other hand, does not address the merits of the case or deny the facts alleged. Instead, it sets up some extrinsic fact that shows why a criminal defendant cannot be tried for the offense charged. Examples of special pleas in bar include:

• Plea of Autrefois Acquit: This plea asserts that the defendant has already been acquitted of the same offense in a previous trial and therefore cannot be tried again for the same crime.
• Plea of Pardon: This plea asserts that the defendant has been granted a pardon for the offense charged and therefore cannot be tried for the same crime.

These examples illustrate how a special plea in bar can be used to prevent a defendant from being tried for a crime. If the court accepts the plea, the case will be dismissed and the defendant will be free from further prosecution for that offense.