Dr James A. Green is lecturer in law at the University of Reading School of Law.
The prohibition of the unilateral use of force, as set out most crucially in Article 2(4) of the UN Charter, is often seen as the archetypal example of a jus cogens norm. Certainly, an overwhelming majority of scholars view the prohibition as having a peremptory character, as does the International Law Commission and the International Court of Justice. It is understandable that a plethora of commentators have perceived the prohibition as a peremptory norm: the use of military force usually involves the systematic killing of human beings, often on a vast scale. An underlying rationale for the entire jus cogens concept is the desire to impose some kind of fundamental standard of common values upon state interaction and to strengthen the effectiveness of international law in certain areas of common concern. On this basis, the prohibition of the use of force is exactly the sort of norm that should be peremptory. Coupled with the fact that jus cogens and the jus ad bellum share common natural law underpinnings, one might view them as a perfect conceptual fit.
In ‘Questioning the Peremptory Status of the Prohibition of the Use of Force’ (2011) 32 Michigan Journal of International Law 215-257, I challenge this widely held view: is the prohibition of the use of force in fact a jus cogens norm? The desirability of peremptory norms, and, indeed, their very existence, has been questioned in the literature, but it was not my aim in the Article to debate the existence of jus cogens norms per se. Without making a value judgment as to the desirability of peremptory norms, the view is taken that there is certainly enough evidence to suggest that states have accepted the general notion of jus cogens flowing from Article 53 of the Vienna Convention on the Law of Treaties.
Based on this starting point, the Article does not argue that the prohibition is necessarily a norm that has failed to achieve peremptory status. Rather, the intention is to demonstrate that there are significant difficulties with such a conclusion and that, as a result, the widespread uncritical acceptance of the prohibition as a jus cogens norm is concerning. The aim is to test the prohibition against the criteria for the establishment of peremptory status—“a norm accepted and recognized by the international community of States as a whole as a norm from which no derogation is permitted and which can be modified only by a subsequent norm of general international law having the same character.”
By way of background, then, the Article sets out in more detail the legal criteria for identifying a peremptory norm of international law, and goes on to consider the majority view—prevalent in the literature—that the prohibition of the use of force is such a norm. A number of problems with the conclusion that the prohibition is jus cogens are then set out. The question of whether the prohibition is suitable, or even capable, of being viewed as a jus cogens norm is examined through various points of focus.