Acta Sunt Servanda? A Regime for Regulating the Unilateral Acts of States at International Law Camille Goodman* I. Introduction Does a written or verbal declaration, made by a state official without any reciprocal commitment, response or acceptance, outside the context of formal negotiations, and to the world at large, give rise to a binding legal obligation? Since the 1974 judgment of the International Court of Justice (ICJ) in the Nuclear Tests Cases, 1 this question can be answered in the affirmative. Whilst doctrine has long been in conflict over whether or not to assign any legal effect to such 'unilateral acts', they have been in constant usage by states in the conduct of their day-to-day relations, and in the development of customary international law. International law has expanded and developed rapidly since 1945 and continues to do so, particularly as the burgeoning pool of actors recognised as subjects of international law, and modem methods of travel and communication, increase the ties connecting the subjects of the international system. Unilateral acts have expanded and developed accordingly, both as a common means by which states conduct international relations, and as an accepted practice recognised in doctrine and jurisprudence. The International Law Commission (ILC) identified unilateral acts of states as a topic suitable for codification and progressive development at its 48 th session in 1996. The Commission noted that although the topic was well delimited and had been the subject of academic writing, it had never been studied by any official international body; that states had abundant recourse to unilateral acts and there was state practice to draw upon in deducing legal principles in relation to them; that although several judgments of the ICJ had considered unilateral acts, there were uncertainties and questions in the dicta; and that the law of treaties could provide a point of departure for the work. 2 LLB (Hons) BA (Int Studies) (University of Adelaide). An earlier version of this paper was submitted as an honours thesis at the University of Adelaide in 2003 and presented at the Australian & New Zealand Society of International Law Conference in 2005. Nuclear Tests (Australia v France) [1974] ICJ Rep 253 and Nuclear Tests (New Zealand v France) [1974] ICJ Rep 457. The judgments in the two cases are essentially the same, and page references in this paper will be to the Australian case. 2 Yearbook of the International Law Commission (vol II, part two, 1996) [245] and annex II, addend 3.