This introductory chapter sets out the framework for the subsequent analysis. It delineates the concrete research topic by defining the legal status and the main characteristics of state responsibility in public international law. Furthermore, this chapter clarifies the research objective of this book, which is to develop an economic theory of how the international law of state responsibility accounts for and could better ensure the protection of community interests. Rational choice theory is presented as the research method to reach this objective and its different assumptions, notably the state as a unitary and rational actor, and its application to international law are outlined and justified. The chapter concludes with defining the research question and giving an overview of the structure of the book.