1. P.C. Jessup, The Price of International Justice (New York, Columbia University Press 1971, at p. 82.
2. Briefly stated, the jus ad bellum refers to the rules applicable prior to the outbreak of war and that govern the circumstances under which a State is permitted to initiate force against another State. See also n. 3 infra. As to the relationship between the jus ad bellum and jus in bello, see E. Koppe, ‘Compensation for War Damages under Jus ad Bellum, infra pp. 417–433.
3. Eritrea-Ethiopia Claims Commission, Partial Award, Jus Ad Bellum — Ethiopia’s Claims 1-8 (19 December 2005), 45 ILM (2006) p. 430 (hereinafter ‘Partial Award’). During the Commission’s proceedings concerning this claim; Eritrea and Ethiopia ‘utilized the terminology of jus ad bellum to describe the law governing the initial resort to force between them. At the hearing of this claim in April 2005, Ethiopia confirmed that it meant by this the use of force contrary to the Charter of the United Nations’. Partial Award, at para. 1, n. 1.
4. See, e.g., Y. Dinstein, War, Aggression and Self-defence, 4th edn. (Cambridge, Cambridge University Press 2005) p. 75 (‘the predominant conviction in the nineteenth (and early twentieth) century was that every State had a right — namely, an interest protected by international law — to embark upon war whenever it pleased. The discretion of States in this matter was portrayed as unfettered’). International law did, however, regulate through the jus in bello how warfare, once commenced, should be conducted.
5. P. Heilborn, Grundbegriffe des Völkerrechts (1912) p. 23, quoted in A. Randelzhofer, ‘Use of Force’, in R. Bernhardt, ed., Encyclopedia of Public International Law, Vol. 4 (Amsterdam, Elsevier 2000) p. 1247. Because of this freedom to wage war, the concept of the right to self-defence remained in large part redundant; its invocation being made merely for political purposes and also in respect of incidents occurring during times of peace. See A. Randelzhofer, ‘Article 51’, in Bruno Simma, ed., The Charter of the United Nations: A Commentary, Vol. I (Oxford, Oxford University Press 2002) p. 789.