The prohibitive subjunctive is a commonly used construction for it's function as both a warning and a polite command. In this paper Prof. Elmer gives this keystone of Latin grammar a thorough inspection, often directly disagreeing (quite correctly) with Latin grammar reference books still in wide use. For the intermediate to advanced student of the Latin language this paper will provide an illuminating re-evaluation of the prohibitive subjunctive that opens new avenues toward understanding the Latin language.