This dissertation argues that reciprocity has been an instrumental component of the state practice of the United States in post-World War II 20 ^th century armed conflict. This contrasts with conventional narratives that argue that the humanitarian emphasis of post-World War II treaties have rendered reciprocity invalid. Despite recent interest in the laws of war, there remain two substantial gaps in the literature that this dissertation has sought to address. Fist, research has yet to thoroughly examine, from the perspective of state practice, the historical role that reciprocity has played in this branch of international law. Second, reciprocity and the laws of war have not been framed within a theoretical model that allows for multiple perspectives of international relations. This dissertation addresses these gaps in two primary ways.

First, this dissertation frames reciprocity and the laws of war within an inclusive theoretical understanding of international relations in the form of The English School tripartite model. This contrasts with much of the literature that has considered this subject from the dichotomous realist/idealist arguments. The English School, by including the international society perspective, provides a powerful explanatory tool with which to conceptually analyze the laws of war and reciprocity.

Second, an historical methodology has been incorporated that emphasizes a comprehensive investigation of primary source material found in key government archives. A methodological model has been developed that examines state practice as a four-stage decision-making process that involves the diplomatic and legislative creation of international treaties, military application of treaty obligations in the form of training doctrine, and executive branch decisions to apply and adhere to the laws of war before and during belligerent conflict. This research seeks to contribute to the historical record of United States practice and to provide the basis for unique contemporary understandings of the laws of war.