This work approaches international law as more than merely information contained in international legal norms, and does not view international law as a body of objective and binding normative commands. As ""legal knowledge"", international law encompasses rules, practices and the expectations actors derive through legal reasoning from conventional legal rules, customary norms, international adjudication, and international legal theory.;The study is in three parts. Part 1 constructs a framework to analyze the effectiveness of international law to influence decision-making within conflict resolution processes. Drawing on the contending approaches of the New Haven School of International Law and its rivals and applying various devices of linkage theory, the analysis isolates variables and indicators of the impact of legal expectations on actors' perceptions about the normative contents of such rules in a particular bargaining process.;Parts II and III apply the framework of Part I to explain the role of international law in the Central American peace negotiations of the 1980s. Using the framework, Parts II and III identify sources of uncertainty and diverging expectations in the Western Hemisphere that aggravated rather than assuaged in Central American crisis. Parts II and III also explain the normative constraints that affected Central American decision-makers and provided the basis for most of the regional consensus within the Esquipulas meeting.;With the help of heuristic devices from the behavioural sciences, this study of international law proposes an alternative to the traditional views of international legal effectiveness in the modern world.