Mandamus means "we order" in Latin; it is the name of one of the
prerogative writs. A
writ of mandamus or simply "mandamus" 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" means "binary" -- the act is either done or not.) In some U.S. states, the writ is now called "mandate" instead of "mandamus."