The themes of this volume, unilateral sanctions and international law, are very important issues of contemporary international relations. These are very much live issues: they are not abstract, and they are certainly not esoteric. When sanctions are imposed, they are intended to have an impact; their purpose is coercive and sometimes punitive. Therefore, the issue of unilateral sanctions is not abstract, although as a concept it may be considered so. It is my presumption that most readers of this volume believe that relations between States must be regulated and must be based on international law. Respect for international law or the principles of international law is the sine qua non for international relations. Unilateral sanctions, on the other hand, involve, as implied, a measure of unilateralism as well as a measure of coercion. Accordingly, tension exists between the concepts of unilateral sanctions and international law. Are these two concepts reconcilable? Can the tension that exists between them be resolved? Unilateral sanctions are coercive measures taken or imposed by one State to punish another State and can take various forms, such as reprisals, retorsion, private justice, self-help, use of force, and third-party justice. I am not suggesting that all these categories are one and the same, but there is, in my view, a common element among them. The common element present in all these different categories is that of coercion or demand for compliance and the act of unilateralism. Unilateral sanctions, at first sight, might seem to challenge the principle of state sovereignty and that of the rule of law. Accordingly, unilateral sanctions could be considered as a challenge to the existing international legal order which is anchored in the UN Charter, according to which sanctions are to be imposed by the UNSC, following a determination that there is a threat to or a breach of international peace and security. As opposed to the multilateral process of UNSC action, unilateral sanctions involve only one State making the determination that there has been a violation of international law or a breach of an international obligation.