1. These constitutive requirements are themselves also rules of treaty law or customary law. They are called “secondary rules” by Walden in the context of customary law. Walden, R.M., “Customary International Law: A Jurisprudential Analysis”, 13 Israel Law Review 1 (1978) p. 86 et seq.Google Scholar

2. Sitting of the European Parliament, 14–18 November 1977, Europa van Morgen 1977 p. 570.

3. I am limiting myself to treaty law and customary law, partly because the third primary source of law mentioned in Art. 38 of the Statute of the International Court of Justice – “the general principles of law recognized by civilised nations” – can, if one so wishes, be reckoned as falling within customary law.

4. See Art. 38(1)(a) of the Statute.

5. Schachter, O., Nawaz, M., Fried, J., Toward wider acceptance of UN Treaties – A Unitar Study (New York 1971).Google Scholar

6. Here, as elsewhere in this lecture, the word “state” is used as pars pro toto for “subjects of international law, in particular states and international organizations”.

7. In 1951, the arbitrator in the Abu Dhabi Case, Lord Asquith, in accordance with the opinion of the International Law Commission (ILC Yearbook 1951, vol. II, p. 142), found that the rule according to which a coastal state has control over the exploitation and exploration of the continental shelf was not “as yet” a rule of customary law (18 International Law Reports pp. 155, 157). In the Continental Shelf Case, the International Court of Justice did admit that, in 1958, it was possible to speak of a rule of law (ICJ Reports 1969, p. 22).

8. The term “conduct model” was used by Tammes, A.J.P. in his recent article “International Law: some themes of discussion”, 19 German Yearbook of International Law (1976) p. 33.Google Scholar

9. An excellent survey of the existing theories, in the context of customary law, is given by Walden, R.M. in “The subjective element in the formation of customary international law”, 12 Israel Law Review (1977) 3, p. 344 et seq.CrossRefGoogle Scholar

10. According to the International Court of Justice in the Continental Shelf Case, ICJ Reports 1969, p. 44.

11. Art. 38(1)(b) of the Statute of the ICJ states that alongside conventions the Court must apply “international custom, as evidence of a general practice accepted as law;”.

12. Convention on the Law of Treaties, 1969 - UN.Doc. A/Conf.39/27. The Convention is concerned only with “international agreements concluded between States in written form …” (Art. 2(1)(a)).

13. See Arts. 1, 2(1)(a) and 3.

14. ILC Yearbook 1969, vol. II, p. 190.

15. This Article is not completely clear since the concept “International conference” is not more closely defined. As a result, it is uncertain in which diplomatic circumstances the term “international conference” should be employed, consequently it will not always be clear in which situations the unanimity rule must be abandoned.

16. See Art. 2(1)(a).

17. Art. 24(2).

18. See Tammes, A.J.P., Hoofdstukken van International Organisaties (The Hague 1951) chapter 1, pp. 3–85CrossRefGoogle Scholar for an extensive analysis of the situation before the Second World War.

19. International Convention for the Prevention of Pollution from Ships, XII International Legal Materials, pp. 1319–1444.

20. Art. 16 says only at what moment a state consents to be bound by the deposit or exchange of instruments of ratification, acceptance, approval or accession. The Article does not say at what moment sufficient states consent, let alone at what moment the consent to be bound of sufficient states has become cognoscible.

21. Art. 77(1)(f).

22. Arts. 10 and 24 allow the parties to agree on what they consider to be appropriate on this point.

23. “Das Vertragsverfahren kan einfach, zusammengesetzt (mehrphasig) oder gemischt sein” (I. Seidl-Hohenveldern), cited approvingly by Verdross, A. in Die Quellen des universellen Völkerrechts (Freiburg 1973) p. 51.Google Scholar

24. The relevant theories were excellently summarized in 1962 by Suy, E. in his book, Les actes juridiques unilatéraux en droit international public (Paris 1962)Google Scholar; see particularly pp. 217–235. Suy himself does not share the confusion, and clearly distinguishes between creation, existence and establishment (by recognition) of customary law.

25. Oppenheim – Lauterpacht call this the “breaking-point”, see p. 15 of Part I of their International Law (7th ed.) (London 1953).Google Scholar

26. That “evidence” (notwithstanding the use of the word “preuve” in the French text) should not be translated in German with the word “Beweismittel” but by the word “Ausdruck” has been made clear by two Austrian authors, S. Verosta and H. Günther – see Verdross, A., Die Quellen des universellen Völkerrechts, at pp. 98, 99.Google Scholar

27. Affaire colombo-péruvienne relative au droit d'asile, CIJ Recueil 1950, p. 276.

28. ICJ Reports, 1969, p. 44.

29. ICJ Reports 1969, p. 43.

30. ICJ Reports 1966, p. 34.

31. See on this, Thirlway, H.W.A., International Customary Law and Codification (Leiden 1972).Google Scholar

32. ICJ Reports 1969, p. 43.

33. CIJ Recueil 1950, p. 276.

34. By passive participation in the rule-forming practice, is understood, inter alia, tolerating the active participation of others in the practice, not resisting the rule-forming acts of other states.

35. ICJ Reports 1969, p. 44. It is noteworthy that in these two sentences the Court distinguishes clearly between, on the one side, habitual conduct of states which fulfils a norm of courtesy, convenience or tradition and, on the other side, habitual conduct (“a settled practice”) that fulfils a legal norm, but that in the first two sentences of the same paragraph the two sorts of norm are not distinguished. Stages 1, 2, and 3 are not only telescoped (which also occurs frequently in treaty law) but are also quite wrongly confused, since the Court states that for the forming of the “opinio juris” … “two conditions must be fulfilled. Not only must the acts concerned [i.e., the acts of states which must be evidence of the custom] amount to a settled practice, but they must also be such, … as to be evidence of a belief that this practice is rendered obligatory by the existence of a rule of law requiring it.” (emphasis added).

It is stated here that all the acts of states which bring about the creation of the rule (“the acts concerned”) must be repeated often enough to “amount to a settled practice”. At the same time, they must evidence the belief that a legal obligation already exists, otherwise there is no law. It is not only the first state which gives evidence of its conviction that it is dealing with a legal rule which is in error; according to this quotation a number of states must first make this error in connection with the legal character of the alleged rule. Moreover, in its other decisions the World Court has never demanded that states had, by their actions, given expression to their opinio juris so frequently and repeatedly. All this is the baleful consequence not only of the failure to distinguish between the creation and the application of law, but also of not distinguishing between stages 1(,2) and 3.

36. Wolfke, K., Custom in Present International Law, (Wroclaw 1964) passim, and in particular pp. 70–76 and 158–166.Google Scholar

37. Perhaps the “Right of Passage over Indian Territory” Case most clearly expresses this. See ICJ Reports 1960, p. 40.

38. The Lotus Case gives an explantory example. See PCIJ Series A No. 10, p. 29.

39. See n. 48.

40. See n. 47.

41. It is submitted that even before the entry into force of the revised (1972) Convention on the international regulations for preventing collisions at sea in July 1977, the obligation to follow the starboard channel in the Dover Straits was an obligation under general international customary law and that, consequently, this obligation cannot now be avoided by non-ratificatiòn of the 1972 Convention. See for some of the relevant IMCO-documents: Churchill, and Nordquist, , New Directions in the Law of the Sea, vol. II p. 508 et seqGoogle Scholar. and vol. IV pp. 235–283.

42. There seems to have been an avoidance of a clear distinction between the creation of rules through “practice” (stage 1) and the creation of law (stage 3) in the formulation of the relevant passage in the “Right of Passage” Case, ICJ Reports 1960, p. 40. At any rate, this is the impression one gets if one compares the Separate Opinion of Judge Wellington Koo and the Dissenting Opinion of Sir Percy Spender with the words of the Court. See ICJ Reports 1960, pp. 63–99.

43. For an example, see n. 35.

44. In two Advisory Opinions, viz., that concerning “La ville libre de Dantzig et l'Organisation International du Travail” (PCIJ Series B, No. 18 at p. 13) and that concerning the “Compétence de la commission européenne du Danube/entre Galatz et Braila (PCIJ Series B, No. 14 at p. 17).

45. In the Asylum Case, the possibility of regional rules of customary law was mentioned, see CIJ Recueil 1950 p. 276. The Court repeated its relevant formulation in 1952 in the “Affaire relative aux droits des ressortissants des Etats—Unis d'Amérique au Moroc”, see CIJ Recueil 1952, p. 200.

46. Bilateral customary law was expressly recognized in the “Right of Passage over Indian Territory” Case, see ICJ Reports 1960, p. 39.

47. See, for example, the leading Soviet writer G.I. Tunkin at p. 130 of his Theory of International Law (London 1974).Google Scholar

48. See, for example, the Course given by Sir Gerald Fitzmaurice (later President of the World Court) in 1957, entitled “The General Principles of International Law Considered from the Standpoint of the Rule of Law”, Hague Recueil (1957) vol. II, at pp. 99–101.Google Scholar

49. CLF Recueil 1951, p. 131. The Court said that even if a ten-mile closing rule for bays already existed, then this rule for establishing the internal waters of a state would be “inopposable à la Norvège celle-ci s'étant toujours élevée contre tout tentative de l'appliquer à la côte norvégienne”.

50. In his Dissenting Opinion in the Continental Shelf Case, ICJ Reports, 1969 p. 230. To the point of view cited in the text is often added that jus cogens can be valid as against a state despite its constant protest. As examples of jus cogens the following are often mentioned: the prohibition on aggression and the prohibition on the infringement of fundamental human rights – the latter incorrectly, in my view. One can possibly include under jus cogens the rules which are fundamental for the legal regime operating in international areas. If the totality of these areas is enlarged or diminished the general interest is directly affected, e.g., no state can avoid, vis à vis other states, the new prohibition on fishing within 200 miles of the coast without the permission of the coastal state, thereby infringing the preferential right of the coastal state.

51. Brierly was contributing to the discussions of the International Law Commission, see ILC Yearbook 1950, vol. I, p. 5. Moreover, as already pointed out, repetition of state acts (a requirement for the passage of stage 1) will take time.

52. ICJ Reports 1969, p. 43.

53. ICJ Reports 1969, p. 42.

54. Fisheries Jurisdiction Case (UK v. Iceland-Merits) ICJ Reports 1974, p. 25.

55. ICJ Reports 1974, p. 25.

56. Idem.

57. Judge Lachs, Dissenting Opinion, ICJ Reports 1969, p. 228.

58. According to Judge Tanaka in his Dissenting Opinion, ICJ Reports 1969, p. 178; Judge Sørensen spoke in the same vein in his Dissenting Opinion, ibid., pp. 245–7.

59. See, Informal Composite Negotiating Text (UN Doc.-A/Conf. 62/WP.10) pp. 13–16.

60. See Art. 38(1)(a) of the Statute of the ICJ.