Abstract Noting that the use of modern instruments of war had unpredictable and revolutionary consequences, Morris Janowitz introduced the concept of a ?constabulary force? to show how a professional military in a liberal democratic state might use modern weapons and yet conserve the existing political order. This article explores the meaning of this concept in three ways. First, it examines the strategic assumptions underlying the concept to explain why Janowitz thought it offered an approach to containing the revolutionary consequences of (...) the use of force that was more promising than alternative concepts of military force. Second, it explores the moral implications of the concept (which Janowitz did not do), identifying key moral commitments a constabulary force must meet to sustain a liberal democratic order as it attempts to resolve dilemmas posed by the use of force. Third, it considers in what way these moral commitments are particular to a constabulary force, while yet preserving an approach to the use of force that could be applied across the spectrum of force by military structures of various kinds. (shrink)