Mandamus

A writ of mandamus or simply mandamus, which means "we order" in Latin, is the name of one of the prerogative writs and is a court order directing someone to perform a specified act. The act must be one that is "ministerial" rather than "discretionary," which means it must not involve any qualitative judgment to tell whether it has been done (or done right or completely): Signing a document or handing one over to someone is ministerial; providing some service is discretionary, whether it is painting a portrait or removing a gall bladder or cutting hair or typing a letter. (In that sense, "ministerial" has a "binary" meaning—the act is either done or not done.)

In the administrative law context in the United States, the requirement that mandamus can be used only to compel a ministerial act has largely been abandoned. By statute or by judicial expansion of the writ of ''mandamus'\' in most of the U.S. states, acts of administrative agencies are now subject to judicial review for abuse of discretion. Judicial review of agencies of the United States federal government for abuse of discretion is authorized by the Administrative Procedure Act.

In the context of mandamus from a United States Court of Appeals to a United States District Court, the Supreme Court of the United States has ruled that the appellate court has discretion to issue mandamus to control an abuse of discretion by the lower court in unusual circumstances, where there is a compelling reason not to wait for an appeal from a final judgment. This discretion is exercised very sparingly. In some state-court systems, however, mandamus has evolved into a general procedure for discretionary appeals from nonfinal trial-court decisions.

In some U.S. states, including California, the writ is now called mandate instead of mandamus. Others, including New York, have replaced mandamus (as well as the other prerogative writs) with statutory procedures. In New York this is known as an Article 78 review after the civil procedure law provision that created the statutory procedure.