The Normative Effects of Advisory Opinions of the International Court of Justice: The Uk-Mauritius Chagos Deal

Focusing on the UK-Mauritius Chagos Agreement, this article maps the normative effects of advisory opinions of the International Court of Justice (“ICJ”). At a time when the advisory function of international courts is resorted to more frequently than ever before, a better understanding of the effects of advisory opinions is needed. ICJ advisory opinions are formally non-binding. As this article argues, however, their normative effects cannot be captured by their non-binding character, or the common understanding that they merely constitute “advice” to the requesting body. Rather, their normativity, as judicial pronouncements that state the law, can be felt across the international legal order, within and outwith the UN system, and in different judicial and non-judicial fora.