A subpoena is generally understood as written order by a government agency (usually the court), to compel testimony or production of evidence from a party in the case, or a third-party.  The court must have authority to compel in order for this to be a legitimate order.  If the party being compelled does not comply, they can face penalties.

There are two types of commonly-known subpoenas:

  1. subpoena ad testificandum   – orders person to testify
  2. subpoena duces tecum – orders person/organization to produce documentation

In Latin “sub poena” translates to “under penalty”.  Some courts and clerks may spell it as subpena.  This term is a carry over from English common law, of which the US court system is heavily influenced.

Example

During a Guam divorce trial, one party accuses the other of adultery, and they believe that email evidence can prove this.  Their lawyer makes a request, and the Guam court subpoenas the opposing party’s place of employment to turn over emails.  Although, this rarely occurs in small civil cases such as divorce trials, it can happen if the court deems it plausible as a form of evidence in the trial decision process.