1. 1155 U.N.T.S.331.

2. By 31 Dec. 1996, 81 States were parties to the Convention; see Multilateral Treaties Deposited with the Secretary-General, Status as at 31 December 1996, UN Doc.ST/LEG/ SER.E/15, p.869.Google Scholar

3. See Art.4 of the Convention.

4. Legal Consequences for States of the Continued Presence of South Africa in Namibia (South West Africa) I.C.J. Rep. 1971, 47.Google Scholar

5. For some recent examples see e.g. Opel Austria GmbH v. Council of the European Union [1997] E.C.R. II–43, 70Google Scholar; R. v. Secretary of State for the Home Department, ex p. Flynn, Queen's Bench Division CO/2310/93, The Times, 23 Mar. 1995;Google ScholarSale v. Haitian Centers Council, Inc. 500 US. 155, 191 (1993).Google Scholar

6. See Brierly, , The Law of Nations (6th edn, 1963), pp. 78–80Google Scholar, and, for a recent comprehensive overview on codification in international law, Jennings, and Watts, (Eds), Oppenheim's International Law (9th edn, 1992), Vol.I/1, pp.96–115.Google Scholar

7. (1966) II Y.B.I.L.C. 176–177.Google Scholar

8. Judgment of 27 September 1997 (1998) 37 I.L.M 162.Google Scholar

9. As the emphasis of this article lies on methodological questions, the treatment of substantive issues is not meant to be exhaustive even as regards the law of treaties: in particular, the role of new norms of international environmental law for the interpretation of treaties will be considered only occasionally; the question of State succession, dealt with at paras.117–124 of the judgment, idem, is entirely omitted.

10. For the complete ten of the Treaty see (1993) 32 I.L.M. 1249Google Scholar

11. The minimum distance between the two barrages depends on the drop of the river, which is extremely low on the relevant section of the Danube. This explains why the Nagymaros barrage had to be situated more than 100 km downstream from Gabcïkovo.

12. See Arts.15, 19 and 20 of the Treaty.

13. For the text of the Declaration of 16 May 1992 see (1993) 32 I.L.M. 1260.Google Scholar

14. Both countries had already expressed their aspiration for membership of the EU.

15. On 1 Jan. 1993 the Czech and Slovak Republics had succeeded to former Czechoslovakia as two independent States.

16. For the text of the Special Agreement see (1993) 32 I.L.M. 1294Google Scholar; under Art.2, the ICJ was requested (1) to decide: (a) whether Hungary had been entitled to suspend and later abandon the works at Nagymaros and Dunakiliti; (b) whether Czechoslovakia had been entitled to proceed to and put into operation Variant C; (c) whether the Hungarian notification of termination was effective; and (2) to determine the consequences arising from these legal findings.

17. More precisely, the ICJ based its decision on the assumption that Hungary's pleadings did not meet the standard of environmental necessity, see judgment, supra n.8, at paras.55–56. While this corresponds with a general tendency among judges to avoid contentious findings on the scientific facts, it is all the more understandable if one takes into account that the ICJ is rather used to historical maps and diplomatic documents as means of factual evidence.

18. Judgment, idem, paras.49–57.

19. Idem, paras.101–104, 112; however, it should also be kept in mind that allowing for unilateral termination of the Treaty by Hungary would practically have excluded the possibility of a later settlement and, thus, would have put the entire burden of the conflict on Slovakia.

20. The two States acceded to the Vienna Convention on 19 June 1987 and 29 July 1987 respectively, see Multilateral Treaties, loc. cit. supra n.2.

21. See Art.4 of the Convention.

22. See judgment, supra n. 8, at para.46, referring to the South West Africa case, supra n.4, the Fisheries Jurisdiction case (Jurisdiction of the Court) I.C.J. Rep. 1973, 18Google Scholar, and the WHO and Egypt case, I.C.J. Rep. 1980, 95–96.Google Scholar Nevertheless, the ICJ did not rely exclusively on the concept of codification: instead, it also recalled that “it had not lost sight of the fact” that the Vienna Convention directly applied to the Protocol of 6 Feb. 1989, by which the two governments bad agreed on a new time schedule for the remaining works. Since this peculiarity may, indeed, have justified a more literal approach, one may regret that the ICJ has wrapped the argument into a somewhat nebulous formula which does not allow one to ascertain its exact significance for the judgment However, the remark indicates that a subsequent agreement governed by the Vienna Convention also enhances its authority with regard to the underlying treaty.

23. Judgment, idem, para.47.

24. Idem, para.101; it should be noted that necessity was never universally accepted as a ground for the unilateral termination of treaties by a majority of States; see Vamvoukos, , Termination of Treaties under International Law (1985), p.202Google Scholar, and Visscher, De, Théorie et Réaltiés en Droit International Public (3rd edn, 1960), pp.338–340.Google Scholar

25. Judgment, idem, paras.55–56.

26. Interestingly, the subchapter dealing with necessity as a ground for unilateral termination in the 3rd edition of De Visscher, op. cit. supra n.24, was replaced with the discussion of fundamental change under the Vienna Convention in the 4th edition (1970), pp.297–298.Google Scholar

27. International Law Commission Draft Articles on the International Responsibility of States (1980) II Y.B.I.L.C. 34.Google Scholar

28. See idem, Art.33, para.2(b).

29. For a general discussion of the relationship between the law of treaties and State responsibility see Reuter, , Introduction to the Law of Treaties (1989), pp.150–153.Google Scholar

30. Judgment, supra n.8, at para.47.

31. (1966) II Y.B.I.L.C 256.Google Scholar

32. For similar tendencies in the private law of contract, see Zweigert, and Kötz, , An Introduction to Comparative Law (2nd edn, 1992), pp.559, 566, 570Google Scholar, and Posner, and Rosenfield, , “Impossibility and Related Doctrines in Contract Law: An Economic Analysis” (1977) 6 J.Leg.stud 83.Google Scholar In English law the problem is discussed under the notion of impracticability; see Treitel, , Frustration and Force Majeure (1994), pp.255–265.Google Scholar

33. Hungary had also argued the relevance of the political changes in Eastern Europe, and the diminishing economic viability of the project. According to the ICJ, neither of these changes had radically altered the obligations under the Treaty within the meaning of Art.62, para.1(b) of the Vienna Convention; see judgment, supra n.8, at para.104.

34. Ibid; as the ICJ had already stated in Fisheries Jurisdiction, supra n.22, at p.17Google Scholar, both factual and legal developments may constitute a fundamental change of circumstances within the meaning of Art.62 of the Vienna Convention.

35. See e.g. the Netherlands Ministry of Justice (Ed.), The Netherlands Civil Code, Book 6, The Law of Obligations, Draft Text and Commentary (1977), pp.582–583Google Scholar, referring to Art.6.5.3.11 of the Dutch Civil Code, the German revalorisation case RGZ 100, 130, 133 (1920), and Art 1467 of the Italian Civil Code, under which the other party can avoid termination for fundamental change by an offer to adapt the terms of the contract.

36. See e.g. the ILC Commentary on Draft Article 59 of the Vienna Convention (1966) II Y.B.I.L.C 257, 259.Google Scholar

37. For the text of the Convention that was adopted on 23 Aug. 1978, see (1978) 17 I.L.M. 1488.Google Scholar

38. The need for objective evaluation makes the balancing test almost inoperable without a neutral judicial authority. Although there is no authority to this effect in the travaux prép-aratoires, the objectivity requirement may in part explain the silence of the Vienna Convention on the issue: for, since adjudication is still the exception in international law, the Convention primarily addresses the State parties themselves. These can hardly be expected to balance their own interests objectively against each other, see also (1996) II Y.B.I.L.C. 260.Google Scholar

39. The two other arguments were rejected on the grounds that Variant C was disproportionate as a countermeasure, and that the duty to mitigate damages does not authorise an act that would otherwise be illegal under international law, see judgment, supra n.8, at paras.80, 85.

40. See Admissibility of Hearings of Petitioners by the Committee on South West Africa, separate opinion of Sir Hersch, Lauterpacht, I.C.J. Rep. 1956, 46Google Scholar

41. See e.g. Reuter, op. cit. supra n.29, at pp. 74–75Google Scholar; Interpretation of Peace treaties (Second Phase) I.C.J. Rep. 1950, 229Google Scholar; US Nationals in Morocco I.C.J. Rep. 1952, 196Google Scholar; South Wat Africa (Second Phase) I.C.J. Rep. 1966, 47–48Google Scholar

42. Judgment, supra n.8, at para.77.

43. Idem, para.78.

44. Idem, para.108.

45. See e.g. (1966) II Y.B.I.L.C. 260.Google Scholar

46. Judgment, supra n.8, at para.110.

47. Idem, para. 109.

48. See also idem, para.48, where the ICJ rejected Hungary's argument that the suspension and later abandonment of works in 1989 implied a tacit suspension of the Treaty within the meaning of the Vienna Convention.

49. Idem, paras.151–154.

50. See e.g. the Wimbledon case, where the PCIJ confirmed the right of the Allies to free passage through the Kiel Canal under Art.380 of the Treaty of Versailles, P.C.I.J. Rep., Ser.A, No.1, pp.24–25.Google Scholar Considering sovereignty over natural resources, the award in the Aminoil arbitration (63 I.L.R. 586–591)Google Scholar upheld the stability clause in an oil concession agreement, but gave it a rather restricted meaning.

51. See the BP Exploration Co. (Libya) Ltd arbitration (53 I.L.R. 346–349)Google Scholar, where the sole arbitrator explicitly ruled out a right to specific performance of a concession agreement under international law, and Gray, , Judicial Remedies in International Law (1987), pp.16–17, 95–108.Google Scholar

52. See e.g. Brownlie, , Principles of Public International Law (4th edn, 1990), p.463Google Scholar, and the Temple case, I.C.J. Rep. 1962, 36–37; the fact that the ruling calling for specific performance usually takes the form of a declaratory judgment reflects the default of judicial enforcement procedures in international law.Google Scholar

53. See also Mann, “The Consequences of International Wrong in International and Municipal Courts” (1976–1977) 48 B.Y.B.I.L. 13.Google Scholar

54. Judgment, supra n.8, at para.104.

55. Idem, para. 140.

56. Idem, para. 134.

57. For an account of the relevant international jurisprudence see Vamvoukos, loc. cit. supra n.24.

58. For a comparative overview from the common law perspective see Treitel, , op. cit. supra n.32, at pp.530–537Google Scholar; as the concept is not part of the common law, there is no established terminology in English. Treitel, ibid, uses the terms “adaptation” and “alteration”. The term “adjustment” is used here because it has occasionally been employed to describe the function of clausula rebus sic stantibus under international law, see Lauterpacht, , The Function of Law in the International Community (1933), p.283.Google Scholar

59. See text accompanying supra nn.37, 38.

60. The difference is exemplified by the revalorisation cases that gave rise to the doctrine of judicial adjustment in Continental Europe after the First World War (see e.g. RGZ 100, 130, 133): thus, when faced with the impact of hyperinflation on a life insurance policy in Anderson v. Equitable Assurance Society of United States [1926] All E.R. Rep. 93, 95Google Scholar, Bankes LJ stated: “One cannot help feeling … that one is bound to give a decision which, in this particular case, works great hardship upon the plaintiff. Speaking for myself, I hope… that this rich and powerful company may see its way to do something eventually to mitigate the hardship to plaintiff. That is, of course, by the way, all we have to do is to deal with questions of law which are raised by this appeal.” Half a century later, the Court of Appeal sanctioned unilateral termination of a water supply contract that had become economically unsustainable due to inflation but, again, left adaptation of the terms to the parties: “Rather than force such unequal terms on the parties, the court should hold that the agreement could be and was properly determined in 1975 by the reasonable notice of six months. This does not mean, of course, that on the expiry of the notice the water company can cut off the supply to the hospital. It will be bound to continue it All that will happen is that the parties will have to negotiate fresh terms of payment… The hospital should be entitled to 5,000 gallons a day free of charge and pay for the excess at a rate which is 70 per cent of the current market rate. I would recommend this solution to these two public authorities in the hope that it will settle their difficulties without troubling the courts further”: Staffordshire Area Health Authority v. South Staffordshire Waterworks Co. [1978] 1 W.L.R. 1387, 1397–1398 (per Lord Denning MR).Google Scholar

61. See e.g. the express reservation for the law of State responsibility in Art.73 of the Convention.

62. See e.g. Interpretation of Peace treaties (Second Phase), supra n.41, rejecting the idea that the right of the Secretary-General to appoint the chairman of an arbitral tribunal extends to the case where one of the parties fails to nominate its own arbitrator and US Nationals in Morocco and South West Africa (Second Phase), both supra n.41.

63. See e.g. the North Sea Continental Shelf cases, I.C J. Rep. 1969, 46–52Google Scholar and Fisheries Jurisdiction (Second Phase), I.C J. Rep. 1974, 30–35.Google Scholar

64. As one may recall, the concept of fundamental change originally derives from the assumption of a tacit clausula rebus sic stantibus as pan of the agreement of the parties; see (1966) II Y.B.I.L.C. 258.Google Scholar