State responsibility (13) The existence and limits of a plea of necessity have given rise to a long-standing controversy among writers. It was for the most part explicitly accepted by the early writers, subject to strict conditions.394 In the nineteenth century, abuses of necessity associated with the idea of “fundamental rights of States” led to a reaction against the doctrine. During the twentieth century, the number of writers opposed to the concept of state of necessity in international law increased, but the balance of doctrine has continued to favour the existence of the plea.395 (14) On balance, State practice and judicial decisions support the view that necessity may constitute a circumstance precluding wrongfulness under certain very limited conditions, and this view is embodied in article 25. The cases show that necessity has been invoked to preclude the wrongfulness of acts contrary to a broad range of obligations, whether customary or conventional in origin.396 It has been invoked to protect a wide variety of interests, including safeguarding the environment, preserving the very existence of the State and its people in time of public emergency, or ensuring the safety of a civilian population. But stringent conditions are imposed before any such plea is allowed. This is reflected in article 25. In particular, to emphasize the exceptional nature of necessity and concerns about its possible abuse, article 25 is cast in negative language (“Necessity may not be invoked … unless”).397 In this respect it mirrors the language of article 62 of the 1969 Vienna Convention dealing with fundamental change of circumstances. It also mirrors that language in establishing, in paragraph 1, two conditions without which necessity may not be invoked and excluding, in paragraph 2, two situations entirely from the scope of the excuse of necessity.398 servation and Management of Fish Stocks (Brussels, 20 April 1995), ILM, vol. 34, No. 5 (September 1995), p. 1260. See also the Agreement for the Implementation of the Provisions of the United Nations Convention on the Law of the Sea of 10 December 1982 relating to the Conservation and Management of Straddling Fish Stocks and Highly Migratory Fish Stocks. 394 See B. Ayala, De jure et officiis bellicis et disciplina militari, libri tres (1582) (Washington, D.C., Carnegie Institution, 1912), vol. II, p. 135; A. Gentili, De iure belli, libri tres (1612) (Oxford, Clarendon Press, 1933), vol. II, p. 351; H. Grotius, De jure belli ac pacis, libri tres (1646) (Oxford, Clarendon Press, 1925), vol. II, pp. 193 et seq.; S. Pufendorf, De jure naturae et gentium, libri octo (1688) (Oxford, Clarendon Press, 1934), vol. II, pp. 295–296; C. Wolff, Jus gentium methodo scientifica pertractatum (1764) (Oxford, Clarendon Press, 1934), pp. 173–174; and E. de Vattel, The Law of Nations or the Principles of Natural Law (1758) (Washington, D.C., Carnegie Institution, 1916), vol. III, p. 149. 395 For a review of the earlier doctrine, see Yearbook … 1980, vol. II (Part Two), pp. 47–49; see also P. A. Pillitu, Lo stato di necessità nel diritto internazionale (University of Perugia/Editrice Licosa, 1981); J. Barboza, “Necessity (revisited) in international law”, Essays in International Law in Honour of Judge Manfred Lachs, J. Makarczyk, ed. (The Hague, Martinus Nijhoff, 1984), p. 27; and R. Boed, “State of necessity as a justification for internationally wrongful conduct”, Yale Human Rights and Development Law Journal, vol. 3 (2000), p. 1. 396 Generally on the irrelevance of the source of the obligation breached, see article 12 and commentary. 397 This negative formulation was referred to by ICJ in the GabčíkovoNagymaros Project case (see footnote 27 above), p. 40, para. 51. 398 A further exclusion, common to all the circumstances precluding wrongfulness, concerns peremptory norms (see article 26 and commentary). 83 (15) The first condition, set out in paragraph 1 (a), is that necessity may only be invoked to safeguard an essential interest from a grave and imminent peril. The extent to which a given interest is “essential” depends on all the circumstances, and cannot be prejudged. It extends to particular interests of the State and its people, as well as of the international community as a whole. Whatever the interest may be, however, it is only when it is threatened by a grave and imminent peril that this condition is satisfied. The peril has to be objectively established and not merely apprehended as possible. In addition to being grave, the peril has to be imminent in the sense of proximate. However, as the Court in the Gabčíkovo-Nagymaros Project case said: That does not exclude ... that a “peril” appearing in the long term might be held to be “imminent” as soon as it is established, at the relevant point in time, that the realization of that peril, however far off it might be, is not thereby any less certain and inevitable.399 Moreover, the course of action taken must be the “only way” available to safeguard that interest. The plea is excluded if there are other (otherwise lawful) means available, even if they may be more costly or less convenient. Thus, in the Gabčíkovo-Nagymaros Project case, the Court was not convinced that the unilateral suspension and abandonment of the Project was the only course open in the circumstances, having regard in particular to the amount of work already done and the money expended on it, and the possibility of remedying any problems by other means.400 The word “way” in paragraph 1 (a) is not limited to unilateral action but may also comprise other forms of conduct available through cooperative action with other States or through international organizations (for example, conservation measures for a fishery taken through the competent regional fisheries agency). Moreover, the requirement of necessity is inherent in the plea: any conduct going beyond what is strictly necessary for the purpose will not be covered. (16) It is not sufficient for the purposes of paragraph 1 (a) that the peril is merely apprehended or contingent. It is true that in questions relating, for example, to conservation and the environment or to the safety of large structures, there will often be issues of scientific uncertainty and different views may be taken by informed experts on whether there is a peril, how grave or imminent it is and whether the means proposed are the only ones available in the circumstances. By definition, in cases of necessity the peril will not yet have occurred. In the GabčíkovoNagymaros Project case the Court noted that the invoking State could not be the sole judge of the necessity,401 but a measure of uncertainty about the future does not necessarily disqualify a State from invoking necessity, if the peril is clearly established on the basis of the evidence reasonably available at the time. (17) The second condition for invoking necessity, set out in paragraph 1 (b), is that the conduct in question must not seriously impair an essential interest of the other State or States concerned, or of the international community as 399 Gabčíkovo-Nagymaros Project (see footnote 27 above), p. 42, para. 54. 400 Ibid., pp. 42–43, para. 55. 401 Ibid., p. 40, para. 51.