Threats of Force and International Law

Article 2 (4) of the United Nations Charter forbids states to use threats of force, yet the meaning of the prohibition is unclear. It is relatively uncontroversial to say that states have not seen the prohibition of the threat of force in the same light as its weightier counterpart, the prohibition of the use of force. One should first ask if and how the threat of force under certain circumstances can contribute to the primary purpose of international law, i.e., maintaining a minimum world order, and second, if in such a case the threat is accepted by the international community at least as legitimate, if not as legal. This is why the present article will try to examine threats of force by adopting a functionalist approach, i.e., by taking into account their function and consequences, as well as the purposes pursued by the threatener. Thus, the present article will try to explore how the illegality of the threat of force has developed since the 1907 Hague Peace Conference and in particular after the entry into force of the UN Charter. Indeed, no threat of force, not even ultimata issued in conformity with Hague Convention 3, would today be legal unless they comply with the customary and Charter provisions on jus ad bellum. After determining what conduct amounts to a threat of the use of force, the status of its prohibition in the framework of the sources of international law will be investigated. Sections 3 and 4 will then discuss the consequences of the threat of force under the law of treaties, the law of state responsibility and international criminal law, as well as the remedies at the disposal of the victim state.