The International Law Commission's Guiding Principles for Unilateral Declarations and its Guide to Practice on Reservations to Treaties are among the recent developments in international law. These developments support a new assessment on how optional clauses - e.g. Art 62(1) of the American Convention on Human Rights) and, especially, the Optional Clause (Art 36(2) of the Statute of the International Court of Justice (ICJ) - can be characterized and treated. The question is in how far optional clauses and the respective declarations can be considered a multilateral treaty or a bundle of...