The Politics of Legal Diplomacy: Understanding State Support Before International Courts

Under what conditions do states support other states before international courts? Intervening in judicial proceedings on behalf of another state is a type of voluntary yet costly signal to the court and other actors. Adapting alliance theory to the politics of legal diplomacy, we derive testable hypotheses about the dynamics of inter-state support in judicial forums. We argue that bureaucratic politics moderates the influence of macro-level factors on state support in legalist settings. The self-contained regime of the European Union with its powerful judicial institutions, repeated interactions and variety of interests (economic, political) offers a suitable proving ground for our hypotheses. Using data from 6000 judicial disputes, we find that cultural proximity between the supporting and the supported state is a more important driver of state interventions than economic variables.