in english common law, a writ is a formal written order issued by a body with administrative or judicial jurisdiction. in modern use this generally is a court. writs are issued by courts directing the person to whom they are addressed to do something or to not do something. writs may also be used to direct other courts or public authorities. the authority for a court to issue a writ is given by the all writs act which is a united states federal statute originally a part of the judiciary act of 1789.