This chapter assesses why international legal obligations are (or are not) complied with, and how they are (or are not) enforced. It begins by drawing a distinction between laws and norms. The chapter then examines the main explanations for international law compliance put forward by both international law and international relations scholars. These may be broadly grouped into two categories: instrumentalist explanations and normative explanations. The chapter also discusses the concept of state responsibility—that is, the body of rules governing when and how states may be held liable for violations of international law. International law-enforcement is indelibly shaped by the condition of international anarchy. According to the concept of self-help, an injured state may, under certain circumstances, unilaterally take countermeasures against the guilty party. Such measures may include sanctions, though these may also be ordered by the UN Security Council as a collective security measure. The international legal system also increasingly makes use of judicial procedures that approximate those found within states. In this connection, the chapter considers the role of courts and tribunals in adjudicating disputes and promoting compliance with international law.
