The tension between power and principle has long been central to international legal discourse. Instrumentalism – the idea that international law can change behaviour, but only by creating constraints and opportunities that affect state interests – straddles this tension. This chapter chronicles the rise, role and contestation of instrumentalism in international legal thought. On its own terms, instrumentalism is a descriptive tool to explain how power and norms interact to shape state behaviour. Critics, however, worry that instrumentalism legitimates power politics by clothing them in the trappings of principled legal arguments. Arguments that international law is not ‘law’ or is widely ineffective – arguments that critics fear are aimed at delegitimizing international law as a normative system – have fuelled these fears. The chapter argues that instrumentalist thinking has largely survived these critiques. Instrumentalism continues to flourish in both academic work and international legal practice, in large part because its usefulness as a descriptive tool has been used to understand how to make international law more effective.
This chapter challenges the role of noncompliance as law-making. It argues that a limited role for law-making through noncompliance is necessary for the international legal system to function effectively. Although noncompliance is frequently seen as mere law-breaking, it can have different ends than cheating on a state's obligations. Moreover, classifying an act as (non)compliance is often a matter of interpretation. It is argued that noncompliance to be an effective law-making technique: 1) must be public; 2) must carry with it a credible threat to continue the violation indefinitely; 3) the normative content of the violation must be acceptable to other states as an alternative rule; and 4) the violator's relative costs of law-making through noncompliance are less than they would be through conventional multilateral law-making channels. Thus, channeling noncompliance into law-making can lead to better compliance outcomes over time and to greater effectiveness for international law.