A subpoena is a writ by a government agency, most often a court, that has authority to compel testimony by a witness or production of evidence under a penalty for failure. There are two common types of subpoena: The term is from the Middle English suppena and the Latin phrase sub poena meaning 'under penalty'. The term may also be spelled 'subpena'. The subpoena has its source in English common law and it is now used almost with universal application throughout the English common law world. However, for civil proceedings in England and Wales, it is now described as a witness summons, as part of reforms to replace Latin terms with English terms which are easier to understand.
Contributions by Innab, Famspear, and JonathanFreed.