Writ

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.
History.
In its earliest form a writ was simply a written order made by the English king to a specified person to undertake a specified action. For example in the feudal era a military summons by the king to one of his tenants-in-chief to appear dressed for battle with his knights at a certain place and time. An early usage survives in the United Kingdom. Also in Canada in a writ of election. This was is a written order issued on behalf of the monarch (in Canada, the Governor General) to local officials (High Sheriffs of every county in historical UK) to hold a general election. Writs were used by the medieval English kings to summon persons to Parliament.
Types of writs.
There have been a great many kinds of writs. Some of the more common types still in use are: