What Is The Plural Of Mandamus?

Here in California, the writ of mandamus may be referred to as a “writ of mandate”.  Cal. Code Civ. Proc. § 1084.  In general, California recognizes two types of mandate proceedings – “ordinary mandate” and “administrative mandate”.  Both types of writs are used to correct administrative agency action, but the types of actions that may be corrected differ.  Section 1085 of the Code of Civil Procedure governs ordinary mandate and it is used to compel agencies to perform ministerial acts.  It is also available to compel the admission of a person to the use and enjoyment of a right or office to which the person is entitled, and from which the person is unlawfully precluded.  A court may issue a write of ordinary mandate against a corporation in the same circumstances.  See Cal. Corp. Code § 2200 ("Any penalty prescribed by Section 2200 or Section 2201 shall be in addition to any remedy by injunction or action for damages or by writ of mandate for the nonperformance of acts and duties enjoined by law upon the corporation or its directors or officers. . . .".   Administrative mandate is governed by Section 1094.5 of the Code of Civil Procedure and is used to review the validity of any final administrative order or decision made as the result of a proceeding in which by law a hearing is required to be given.

"Mandamus" is actually a first person plural present indicative active Latin verb, which can be translated as "we command" or "we order".  Because "mandamus" ends in "us" and is Latin, one might be tempted to assume that it its plural form should end in "i" like "cactus/cacti" or "amicus/amici",  However, "mandamus" is a verb, not a noun, and is already plural.  Therefore, the plural form of "mandamus" in Latin is "mandamus".  In English, however, "mandamus" is used as a noun, not a verb.  Because "mandamus" ends in "s".  Thus, the plural in English would be "mandamuses".  See, e.g., Specialty Healthcare Mgmt., Inc. v. St. Mary Parish Hosp., 220 F.3d 650, 653 (5th Cir. 2000) ("In these cases, Rule 69(a) was not used; mandamuses issued under Rule 70.").