The legal term writ of mandamus refers to an order by a court to a lesser government official to perform an act required by law, which he has refused or neglected to do.
A writ or order of mandamus is an extraordinary court order because it is made without the benefit of full judicial process, or before a case has concluded. It may be issued by a court at any time that it is appropriate, but it is usually issued in a case that has already begun.