A subpoena (or )'s commonly defined as a written command to a person to testify before a court or be punished. More accurately, a subpoena's the conditional threat of punishment made by a governmental authority. It's attached to a command, so that if the recipient doesn't do as commanded then he may be punished. Subpoenas are associated with common law legal systems. There're two common types of subpoenas: A subpoena ad testificandum orders a person to testify before the ordering authority or… (More on Subpoena)