This book examines how the United Nations Security Council, in exercising its power to impose binding non-forcible measures (‘sanctions’) under Article 41 of the UN Charter, may violate international law, i.e., limits on its power imposed by the UN Charter itself and by general international law, including human rights guarantees. Such acts may engage the international responsibility of the United Nations, the organization of which the Security Council is an organ. The book then proceeds to examine how (and by whom) the engagement of this responsibility can be determined, i.e., who it is that can find the Council to have acted unlawfully. Most importantly, the book discusses how (and by whom) the responsibility of the UN for unlawful Security Council sanctions can be implemented, i.e., how (and by whom) the UN can be held to account for Security Council excesses. The central thesis is that States can react to unlawful sanctions imposed by the Security Council in a decentralized manner by disobeying the Security Council's command. In international law, this disobedience can be justified as being a countermeasure to the Security Council's unlawful act. Recent practice of States, whether undertaken by executives or, increasingly, by domestic courts, evidences an augmenting tendency to disobey sanctions that are perceived as unlawful. After discussing other possible qualifications of disobedience under international law, the book concludes that this practice can (and should) be qualified as a countermeasure.

This article examines the question of who will be subject to ICC jurisdiction with respect to the crime of aggression. One of the most contentious questions in the negotiations regarding the crime of aggression was whether the Court would have jurisdiction over nationals of a state that does not ratify the aggression amendments, but which is alleged to have committed an act of aggression on the territory of a state has accepted the aggression amendments. The question is examined here against the background of the rules in the law of treaties regarding amendments and treaty interpretation. The article considers the legal effect that the resolution of the ICC Assembly of States Parties (ASP), adopted in New York in December 2017 and activating ICC jurisdiction over aggression, will have in determining this jurisdictional question. A resolution of an international conference adopted by consensus can, in principle, be regarded as subsequent practice or a subsequent agreement of the parties to the Rome Statute that establishes the authentic interpretation of the Statute within the meaning of the Vienna Convention on the Law of Treaties. It is argued however that this particular resolution does not, in itself, provide the definitive answer as to the correct interpretation of the Rome Statute. Despite being adopted by consensus, and despite being highly relevant for the interpretation of the Rome Statute and Kampala Amendments, this resolution does not necessarily amount to a subsequent agreement or subsequent practice that the Court is legally bound to follow. Nevertheless, it is further argued that the position adopted in New York with regard to the jurisdiction of the Court over nationals of states parties that do not ratify the aggression amendments is the correct legal position and the one that the Court, including the Office of the Prosecutor, ought to adopt. The answer to the question over whom the Court will have jurisdiction with respect to aggression is to be found in Rome rather than in Kampala. We argue that the key to addressing this issue is to understand how the amendment provisions of the Rome Statute work in conjunction with basic principles of the law of treaties.