Skip to main content Accessibility help

‘General principles of law’, ‘soft’ law and the identification of international law*

Published online by Cambridge University Press:  07 July 2009

Get access


Treaties and custom are generally regarded as the major sources of international law. They derive their validity more or less directly from the consent of those subjects of the law which also possess the institutional authority to make law. The perceived limitations of the consensual nature of these two sources have resulted in doctrinal controversy concerning, inter alia, the existence of sources of international law which are not essentially consensual. This is the rationale for the inclusion of general principles of law recognised by civilised nations alongside treaties and customary international law in Article 38 of the Statute of the International Court of Justice, as one of the sources of international law to which the Court may refer. Similarly, the phenomenon of ‘soft’ international law is, by and large, a response to the failure to generate the full measure of State consent required for attributing full legal status to the ‘soft’ norms in question, often in relation to developing fields of international concern. It is often said that these non-consensual sources have an inferior status when compared with the consensual ones. The purpose of this paper is to consider critically the basis and the form of the differentiation between these two apparently non-consensual phenomena (i.e., ‘general principles’ and ‘soft’ law) on the one hand, and the paradigmatic (because consensual) types of international law (i.e., treaties and custom) on the other.

Copyright © T.M.C. Asser Press 1997

Access options

Get access to the full version of this content by using one of the access options below.


1. The following is a representative view of the traditional law-making process: ‘Ever since the beginning of the international community States have spontaneously evolved two methods for creating legally binding rules: treaties and custom. Both were admirably suited to the exigencies of their creators. Both responded to the basic need of not imposing duties on such States as did not wish to be bound by them. No outside “legislator” was tolerated: law was brought into being by the very States which were to be bound by it. Consequently there was complete coincidence of lawmakers and law-addressees. Treaties in particular, being applicable to the contracting parties only, perfectly reflected the substantial individualism of the international community. As to custom, it did admittedly give rise to norms binding on all members of the community, but any member could object to the applicability of a customary rule at the moment of its formation, thereby avoiding being restrained by any rule which was not to its liking. Custom too, ultimately resorted to a consensual basis.’(Cassese, A., International Law in a Divided World (1986) p. 169Google Scholar, para. 93). Even according to less-consensual theories of customary law, there must be consent of at least certain States; in Judge Lachs' words, ‘for to become binding, a rule or principle of international law need not pass the test of universal acceptance… The evidence is to be sought in the behaviour of a great number of States, possibly the great majority of States, in any case the great majority of interested States.’ (see ICJ Rep. (1969) p. 229).

2. Cassese, op. cit. n. 1, at pp. 170–174, para. 94.

3. For a discussion of the problem of ‘soft’ law, see Cassese, A. and Weiler, J., Change and Stability in International Law-Making (1986) pp. 66101.Google Scholar

4. Weil, P., ‘Towards Relative Normativity in International Law?’, 77 AJIL (1983) p. 413, at p. 420CrossRefGoogle Scholar. See also Tunkin, G., A Theory of International Law, translated by Butler, W.E. (1974) Chapter 7Google Scholar; Henkin, L., International Law: Politics and Values (1995) p. 40.Google Scholar

5. See section 2 below.

6. See section 3 below.

7. Schachter, O., International Law in Theory and International Practice (1991) p. 49Google Scholar, has written, in relation to general principles and equity, that ‘[w]hat they have in common is an appeal to reason and moral ideas. Because of that, they can be presented as normatively superior to rules or goals … There is concern, on the one side, that they allow too much room for subjective and unilateral judgments and on the other side, that they introduce standards that may supersede State needs or goals.’

8. Logical differentiation is different from hierarchical differentiation in the sense that the latter, unlike the former, is not concerned with the differences between legal categories; rather, it is concerned with the substance of a given rule. To illustrate, two rules of custom cannot be logically differentiated because they are rules of the same logical form, i.e., custom; but they can be differentiated hierarchically, on the basis that one of them protects a much more important value than the other. Both kinds of differentiation are, however, not mutually exclusive. One rule of custom could be both hierarchically and logically differentiated from another.

9. See for example, Brownlie, I., Principles of Public International Law, 4th edn. (1990) p. 287Google Scholar, who identifies as one of the corollaries of the principle of sovereignty [of States] ‘the dependence of obligations arising from customary law and treaties on the consent of the obligor.’

10. Jerome Frank has written, in the context of municipal law: ‘If one accepts as correct the conventional description of how courts reach their decisions, then any decision of any lawsuit results from the application of a legal rule or rules to the facts of the suit. That sounds rather simple, and apparently renders it fairly easy to prophesy the decision, even of a case not yet commenced or tried, especially when as often happens, the rule is definite and precise … But particularly when pivotal testimony at the trial is oral and conflicting … the trial court's ‘finding’ of the facts involves a multitude of elusive factors. First, the trial judge in a non-jury trial or the jury in a jury trial must learn about the facts from the witnesses; and witnesses being humanly fallible, frequently make mistakes in observation of what they saw or heard … Second, the trial judges or juries, also human, may have prejudices … In that respect, neither judges nor jurors are standardized … The chief obstacle to prophesying a trial-court decision is, then, the inability, thanks to these inscrutable factors, to foresee what a particular trial judge or jury will believe to be the facts … These difficulties have been overlooked by most … who write on the subject of legal certainty or the prediction of decisions’ (Law and the Modern Mind, 6th impression (1949) at pp. xxiGoogle Scholar. On the movement known as ‘fact-skepticism’ in general, see Freeman, M.D.A., Lloyd's Introduction to Jurisprudence, 6th edn. (1994) at pp. 659661 n. 26Google Scholar, especially at p. 660). Frank's views may be applied to the field of international law. See also Henkin's remark that ‘[a]t times whether there is a violation of [international] law may depend on complex, ambiguous, or disputed issues about facts and how they may properly be characterized’ (How Nations Behave: Law and Foreign Policy, 2nd edn. (1979) p. 73Google Scholar. See also Hart, H. L. A., The Concept of Law, 2nd edn. (1994) pp. 124 et seq.Google Scholar, and Lim, C. and Elias, O., ‘The Role of Treaties in the Contemporary International Legal Order’, 66Nordic JIL (Acta Scandinavica Juris Gentium) (1997) Vol. 1, p. 1, at pp. 311Google Scholar section 2.1, entitled ‘The Attraction of Treaties’.

11. The following characterisation of the nature of legal disputes draws on the work of Dworkin, R.. See his Law's Empire (1986)Google Scholar, Chapter One, and Gavison, R. (ed.). Issues in Contemporary Legal Philosophy: Essays in Honour of H.L.A. Hart (1987) pp. 913.Google Scholar

12. ICJ Rep. (1969) p. 4. This case is convenient because it raised questions of both treaty law and customary law.

13. See the Case Concerning Maritime Delimitation and Territorial Questions between Qatar and Bahrain, ICJ Rep. (1994) p. 112Google Scholar, where the issue was whether the Doha Minutes, being the agreed record of a meeting between the States concerned, constituted a treaty in international law. See also the North Sea cases (ibid.), where Denmark and the Netherlands argued that, while the Federal Republic had not ratified the 1958 Geneva Convention on the Continental Shelf, it was nevertheless bound by i t ‘… because by conduct, by public statements and proclamations, and in other ways, the Republic ha[d] unilaterally assumed the obligations of the Convention’ (para. 27 of the Judgment, ibid.). This is an argument about the creation of treaty obligations, to the effect that non-ratification by a State does not preclude the applicability of a treaty against that State. The two Kingdoms may appear to be arguing on the basis of custom or estoppel, rather than treaty; but the fact that the Court dealt with custom (paras. 37–82) and estoppel (paras. 30–32) separately from its response to the treaty argument (paras. 28–30), as well as the fact that the two Kingdoms argued on the basis of custom and estoppel separately from the passage under consideration (see the remainder of para. 27), would suggest that this was a treaty argument, i.e., an argument about the truth-conditions for the existence of treaty obligations.

14. See for example, the Dissenting Opinions of Judges Tanaka (ibid., pp.176–179), Lachs (ibid. pp. 230–232, esp. 231) and Srrensen (pp. 246–247), doubting the need for strict insistence of proof of opinio juris.

15. See e.g., the Court's paraphrasing in the North Sea cases (ibid.) of the argument of the two Kingdoms to the effect that even if Germany was not bound as a matter of treaty, it was bound by the equidistance rule because that rule had passed into the body of customary law, ‘… and, like other rules of general or customary international law, is binding on the Federal Republic automatically and independent of any specific assent, direct or indirect’ on Germany's part (para. 37). The Court did not rule specifically on this point; as it found that there was insufficient evidence of a custom, there was no need to consider whether Germany's specific consent thereto was required.

16. See n. 1 above.

17. See Mendelson, M., ‘Practice, Propaganda and Principle in International Law’, (1989) Current Legal Problems, pp. 89Google Scholar: ‘… if you can present your demand as an existing right, it is the other government who would ostensibly be disturbing the status quo by denying it, and not you by making the demand.’

18. See e.g., the German Memorial and Replies in the North Sea cases, loc. cit. n. 12, at pp. 8–9.

19. See e.g., the Danish and Dutch Counter-Memorials, loc. cit. n. 12, at p. 10.

20. The only answer to these questions is an overly cynical one; i.e., lawyers and judges are conniving to keep the truth from their clients so as not to disillusion them, thereby perpetuating their own profession. This is hardly defensible.

21. See e.g., D'Amato, , The Concept of Custom in International Law (1971) p. 88.Google Scholar

22. The distinction between clear and borderline cases also assumes, by referring to ‘clear’ cases, that the meaning of words and concepts are fixed, precise or exact. But as has been demonstrated in legal and other contexts, this is not the case. See L. Wittgenstein, Philosophical Investigations, translated by G.E.M. Anscombe (1974) paras. 37–42, esp. paras. 39 and 40. See Lim and Elias, loc. cit. n. 10, in text accompanying nn. 28–31.

23. See e.g., Lowe, V., 17 Journal of Law and Society (1990) p. 386CrossRefGoogle Scholar (book review of Koskenniemi's, M.From Apology to Utopia: The Structure of International Legal Argument (1989)) at p. 388Google Scholar, where this point is made.

24. See e.g., Redfem, A. and Hunter, M., International Commercial Arbitration (1986) pp.209216Google Scholar (for arbitrations) and Brownlie, loc. cit. n. 9, at pp. 718–730 (on the World Court) for discussion of the problems of consent to the jurisdiction of third-party decision-makers.

25. Henkin, L. (‘General Course on Public International Law’, 216 Hague Recueil (1989-IV) p. 54)Google Scholar wrote that ‘[t]he norm governing the making of customary law-the requirement of consistent general practice plus opinio juris - is based on the constitutional conceptions of the State system, but developed by custom, by general repeated practice and acceptance’. V. Lowe also wrote that ‘[t]he secondary rule of law creation will itself be a rule of customary international law derived from state practice’ (‘Do General Rules of International Law Exist?’, 9 Review of International Studies (1983) p. 207, at p. 209).Google Scholar

26. It is no answer to these arguments to say that there are normal processes of legal reasoning which decision-makers must apply, and that this is what distinguishes the third-party's enterprise from that which the parties could do themselves. The simple point is that States, in the traditional conception of the international legal system, do serve executive, judicial (i.e., relating to interpretation and application of the law) and legislative functions. See B. Cheng, ‘The Future of General State Practice in a Divided World’, in MacDonald, and Johnston, , The Structure and Processes of International Law: Essays in Legal Philosophy, Doctrine and Theory (1983) p. 523Google Scholar. He points out that what he describes as ‘auto-interpretative’ international law ‘represents the bulk of international law’. States, through the medium of their officials, can and do interpret and apply rules of international law, so that the substantive function of a third-party decision-maker is routinely performed by the subjects of the law themselves. The normal processes of legal reasoning, the inherent discretion involved in the exercise of applying the (general) rule to the (particular) facts, and the implicit processes of defining the scope of the applicable rule and the classification of the facts do not require a third-party decision-maker. All these things can be and are undertaken by States and other subjects of the law in everyday international legal discourse.

27. In the Minquiers and Ecrehos case (ICJ Rep (1953) p. 47)Google Scholar, instead of using the optional clause, the parties submitted their case by special agreement, thereby giving themselves a greater degree of control over the nature of the judgment. Both States wanted a judgment ruling that full sovereignty over the disputed islets and rocks belonged to one or the other State, rather than a declaration that these areas were terra nullius or a condominium. They thus formulated their submissions to guide the Court accordingly. And it worked; the Court found, on p. 52, that ‘[b]y the formulation of Article I the Parties have excluded the status of res nullius as well as that of condominium.’ Similarly, in the North Sea Continental Shelf cases (loc. cit. n. 12, at p. 13, para. 2), the Court recognised that it was ‘requested to … to decide what are the applicable “principles and rules of international law”’, rather than actually delimiting the boundaries itself. See Bowett, D. W., ‘Contemporary Developments in Legal Techniques in the Settlement of Disputes’, Hague Recueil (1983-II) p. 170, at p. 197Google Scholar, for a survey of the different kinds of requests made of third-party adjudicators by the Parties.

28. A well-known example of this is the SS Lotus case (PCIJ Rep., Series A, no 10), the ruling in which was rejected by the International Law Commission in its draft articles on the law of the sea (see ILC Yearbook (1956–11) and by the United Convention on the Law of the Sea (1982) Art. 11(1). See also the views expressed on the Nottebohm judgment (ICJ Rep. (1955) p. 4) in the Flegenheimer case (25 ILR (1958-I) p. 91 at pp. 148–50); the General Assembly's response to the Admissions case (ICJ Rep. 1947–8) p. 65 (see Rosenne, S., ‘On the Non-use of the Advisory Competence of the International Court of Justice’, 39 BYIL (1963) p. 1 at pp. 4043)Google Scholar; the statement by the American Secretary of State concerning the law applied by the Permanent Court of Arbitration in the case concerning the Norwegian Shipowners' Claims (I RIAA (1948) pp. 344–346), stating that ‘My Government finds itself compelled to say that it cannot accept certain apparent bases of the award as being declaratory of [international] law or as hereafter binding on this Government as a precedent.’ The letter containing the statement proceeded to mention the particular rules against which the Government felt obliged to protest. The point of all these examples is to show that it cannot be true, certainly not always, that by referring a case to a third-party, the parties have given that third-party a free hand. For a discussion of the problems caused where third parties may be seen to have gone to far, see Bowett, loc. cit. n. 27, at p. 194–201.

29. See e.g., the N. V. Algemene Transport- en Expeditie Onderneming van Gend en Loos v. Nederlandse Admnistratie der Belastingen case before the European Court of Justice in 1963 (case 26/62 [1963] ECR 1), where the Court ruled that the principle of direct effect was implicit in the EEC Treaty. Strongly worded interventions were made by three of the six Member States of the Community to the effect that they had not intended, when they signed the treaty, to allow immediate enforceability of Treaty provisions by individual applicants in national courts. Of course the Court had compulsory jurisdiction, and the judgment was binding in law. But it is surely paradoxical that a third-party can tell a signatory to a treaty, only five years after that treaty was concluded, that the party had not willed what it said it had willed?

30. See M. Koskenniemi, loc. cit. n. 23, Chapter 1, for an alternative analysis of this problem. However, while Koskenniemi's analysis of the structure of international legal argument shows that there are two dimensions to legal argumentation which reflect a tension between the need for concreteness and the need for normativity, we try to show that concreteness and normativity are intimately related. Participation leads to specificity and normativity force, and lack of participation leads to lack of specificity and lack of normative force. As such, we do not dwell on the tension that Koskenniemi alludes to. But our conclusions are the same. We find that legal decision-making, in so far as it seeks to rely upon doctrine, which itself results from consent, faces the problem of what indeed the object of consent looks like. Now, Koskenniemi portrays a straightforward tension between received doctrine and consent whereas we emphasize how doctrine is the result of consent and therefore faces the problem of what that consent consists of in a particular case where the consent of States are meant to have resolved the problem, and yet cannot. We direct our attention to the problematic notion of consent itself, without talking about any tension that there may be between consent and doctrine. It might be said that Koskenniemi describes a problem which we try to locate in the notion of consent itself. But our conclusions are, naturally, similar. Koskenniemi's explanation is contextual in the sense that it looks towards the political environment in which the law resides, but ours is formalistic and conceptual, and looks merely towards the internal coherence of our received doctrine.

The foregoing should not be taken, because it focuses on disputes, to rest on the assumption that dispute resolution is the central function that the law serves. The reason why disputes are the basis of the foregoing arguments is that they are the most illuminating setting in which the assumptions and claims of the participants in the system can be scrutinised, since they are most explicitly discussed in that setting. Hard cases, which are the subject of dispute, test the limits of legal rules and concepts explicitly, and are thus by far the most worthwhile setting for an analysis of the process of law-identification.

31. The point is that any legal philosophy which subscribes to any form of ‘pedigree’ test must face this problem. In other words, if any kind of law is to be derived from a particular source (be it explicit legislation through consentor otherwise, morality orsocial necessity), legaldisputes should not arise because that source should stipulate the law.

32. Schachter, loc. cit. n. 7, provides a convenient taxonomy of the different meanings that have been attached to the phrase ‘general principles’, and the following discussion uses his categories as a basis. He identified five meanings, which shall be examined along with some other suggestions as to the meaning of the phrase. See also Vitanyi, B., ‘Les positions doctrinales concernant le sens de la notion de ‘principes généraux reconnus par les nations civilisées86 RGIDP (1982) p. 48Google Scholar. For a useful bibliography on the subject of general principles, see Lammers, J.G., ‘General Principles of Law Recognised by Civilized Nations’, in Essays on the Development of the International Legal Order (Mélanges Panhuys) (1980) p. 3, at n. 1.Google Scholar

33. The aim of this discussion of general principles is not to provide an exhaustive list of the kinds of general principles that there are, nor is it to provide exhaustive analyses of each kind of general principle identified. The purpose is to consider the problems raised in how to determine that a given principle is one which exists independent of treaties and custom, and to compare those problems with those raised in the process of identifying a treaty or customary rule.

34. Cassese, loc. cit. n. 1, at p. 171.

35. Permanent Court of International Justice, Advisory Committee of Jurists, Procès-Verbaux of the Proceedings of the Committee (1922) pp. 286 et seq.

36. Cassese, loc. cit. n. 1, at p. 172. In Lord Phillimore's often-quoted words, ‘the general principles referred to … were those which were accepted by all nations in foro domestico, such as certain principles of procedure, the principle of good faith, and the principle of res judicata, etc.’ (Procès-verbaux, idem., n. 30, at p. 335).

37. See e.g., Tunkin, loc. cit. n. 4, at pp. 184–185; Kelsen, H., in Principles of International Law, Tucker, A., ed., 2nd edn., (1966) pp. 539540Google Scholar; Guggenheim, P., Traité de droit international public, Vol. 1 (1953) pp. 152,162Google Scholar; Rousseau, C., Droit international public, 5th edn., Vol. 1 (1970) p. 371.Google Scholar

38. Tunkin, loc. cit. n. 4, at p. 191.

39. Ibid., at pp. 197–198; see also Kelsen, loc. cit. n. 37, at p. 540.

40. See Lammers, loc. cit. n. 32, at p. 56, especially n. 11 (for the argument that the drafting history of Article 38 does not bear the interpretation suggested by Tunkin and Kelsen).

41. Tunkin. loc. cit. n. 4, at pp. 199–200.

42. This is particularly odd in the case of Kelsen, an avowed monist. See e.g., loc. cit. n. 37, at pp. 553–88, and his General Theory of Law and State (1945) at pp. 363-80.Google Scholar

43. In the SS Lotus case (loc. cit. n. 28), the search for a rule of customary law compelling States not to prosecute offenders in M. Demons' circumstances involved an examination of domestic laws of the States. One can only speculate whether States enacted these laws with international law in mind, or whether they were simply focusing on regulating their own rules of domestic criminal procedure. The point is that it is not always possible to distinguish between practice which is purely municipal and practice which is supposed to have international legal significance.

44. See e.g., Lauterpacht, H., Private Law Sources and Analogies of International Law (1929) Chapters III-VIIIGoogle Scholar; Brownlie, loc. cit. n. 9, pp. 17–18; SirJennings, R. and Watts, A., Oppenheim's International Law, 9th edn., Vol. 1 (1992) pp. 3640Google Scholar, for detailed lists of the application of general principles of municipal law in international cases, both before the World Court and other tribunals. In particular, see p. 39 of the latter, regarding tribunals other than the World Court:‘… a number of international tribunals, although not bound by the Statute, have treated that paragraph of Article 38 as declaratory of existing law and have relied on “general principles of law” in reaching their decision.’ See further, Ibid. p. 40: ‘General principles of law, however, do not have just a supplementary role, but may give rise to rules of independent legal force; and it is to be noted that general principles of law are included in Article 38 of the Statute of the Court in the same manner as are treaties and custom, rather than as one of the “subsidiary means” referred to in Article 38(1)(d).’

45. Thirlway, H.W.A., ‘The Law and Procedure of the International Court of Justice: Part Two’, 61 BYIL (1990)p. 11. at p. 113.Google Scholar

46. For similar views, see Jennings and Watts, loc. cit. n. 44, at p. 37, and Judge Sir Arnold McNair's much-quoted statement in the International Status of South-West Africa case, ICJ Rep. (1950) p. 120, at p. 132: ‘The way in which international law borrows from [municipal law] is not by means of importing private law institutions “lock, stock and barrel”, ready made and fully equipped with a set of rules … In my opinion the true view of the duty of international tribunals in this matter is to regard any features or terminology which are reminiscent of the rules and institutions of private law as an indication of policies and principles rather than as directly importing these rules and institutions.’

47. See e.g., the North Atlantic Fisheries case, 1 Hague Court Reports (1910) p. 141Google Scholar, where the tribunal refused to apply the concept of servitude; the International Court's Advisory Opinion on the International Status of South-West Africa, idem., p. 120, at p. 132, esp. Judge McNair's Separate Opinion, at pp. 148–153 (on the applicability of the private law concepts of mandate, trust and agency); the Right of Passage case, ICJ Rep. (1960) p. 6, where the Court effectively distinguished between ‘the universal practice of States’ whose municipal laws recognised that ‘the holder of enclaved land has a right, for purposes of access to it, to pass through adjoining land’ (Portuguese submission, pp. 11–12) on the one hand, and intentional law rights of transit over State territory on the other (see Thirlway, loc. cit. n. 45, at p. 119). Brownlie, loc. cit. n. 9, at p. 16, also mentions the differences between the international law on acquisition of territory and the effect of duress on treaties on the one hand and their domestic counterparts on the other.

48. The term is taken from Brownlie, idem., who underscores the importance of the consideration that the widespread recognition of a given principle is not sufficient; the principle must be suitable otherwise than on grounds of widespread recognition for application at the international level.

49. For analysis of the differences between Socialist and bourgeois legal systems, see David, R. and Brierly, J.E.C., Major Legal Systems in the World Today, 3rd edn. (1985) pp. 155306Google Scholar. The reluctance of Socialist countries to submit disputes to third-party settlement means that there have not been cases where the applicability of a general principle not found in the legal systems of such countries was in dispute. The Russian Indemnity case (Russia v. Turkey, Hague Court Reports (1912) p. 297) was decided before the Russian Revolution.

50. See Henkin, loc. cit. n. 4, at p. 40. See also Lauterpacht, loc. cit. n. 44, at pp. 69–70 (the principle must be ‘a principle not belonging to the system of law prevalent in one country, but expressing a rule of uniform application in all or in the main systems of private jurisprudence.’).

51. ICJ Rep. (1962) p. 4.

52. Ibid., p. 49.

53. ICJ Rep. (1966) p. 5, at p. 47, para. 88.

54. ICJ Rep. (1970) p. 2, at p. 37, para. 50.

55. Ibid., p. 277, para. 16.

56. 1 ICLQ (1952) p. 247, at pp. 250–251.

57. Texaco Overseas Petroleum Co. and California Asiatic Oil Co. v. Libya, 53 ILR (1977) p. 389, at pp. 467–468.

58. 6 Iran-USCTR (1984) p. 149, at pp. 168–169.

59. Akehurst, M., ‘Equity and General Principles of Law’, 25 ICLQ (1976) p. 824CrossRefGoogle Scholar. See also Lammers, loc. cit. n. 32, at pp. 62–64, and 69, for the view that there is nothing to stop the application of principles recognised by States within a limited region only, in the same way as the wording of sub-paragraph (b) on customary has not prevented the application of regional and bilateral customary law. For the argument that no meaningful distinction can be drawn between general and non-general custom, see Elias, O., ‘The Relationship Between General and Particular Customary International Law’, 8 African Journal of International and Comparative Law (1996) p. 67.Google Scholar

60. The same applies whether one adopts a narrow consensual view of custom (i.e., that no State can be bound without its consent) or a broad one (i.e., that only widespread or general practice is required, not a universal one), or whether one is dealing with general custom or custom of more limited scope.

61. See section above.

62. Lauterpacht, loc. cit. n. 44, at p. 63.

63. See e.g., Cassese, loc. cit. n. 1.

64. Schachter, loc. cit. n. 7, p. 51. See also Mosler, H., The International Society as a Legal Community (1980) pp. 134 et seq.Google Scholar. The principle of good faith may also be included in this category.

65. Henkin, loc. cit. n. 4.

66. Henkin's list includes ‘the concepts of state and government, territory, population; the equality of states; state autonomy and its implications, notably the requirement of state consent and the effectiveness of consent to bind the state; territorial integrity and inviolability and the impermeability of the state as an entity; the principle of pacta sum servanda; the concept of nationality; perhaps also established norms of diplomatic intercourse’; Henkin, loc. cit. n. 4, at p. 31.

67. The distinction between the mode of creation of customary law when compared with treaties is, in Henkin's terms, ‘[t]reaty law is made; customary law results. Treaties are made by an act of will, purposefully; custom develops. Treaties are prospective; custom is realised retrospectively’ (Henkin, loc. cit. n. 4, at pp. 27–28.). This is not, in traditional terms, a controversial view, although there is compelling evidence to suggest that custom is now being made purposefully; see Stein, T., ‘The Approach of the Different Drummer: The Principle of the Persistent Objector in International Law’, 26 Harvard ILJ (1985) p. 457, at p. 463 et seq.Google Scholar

68. Some of these constitutional norms have been changed over the years; for example, ‘the effectiveness of consent to bind the state’ is now subject to the concept of jus cogens. Similarly, as to the meaning of the principle of non-intervention in the domestic affairs of States, see also the Nationality Decrees Issued in Tunis and Morocco (PCIJ Rep. (1923), Series B, No. 4), where the Court stated that ‘[t]he question whether a certain matter is or is not within the jurisdiction of a state is an essentially relative question; it depends upon the development of international relations … it may well happen that … in a matter which … is not, in principle, regulated by international law, the right of a state to use its discretion is nevertheless limited by obligations it may have assumed towards other States.’ See also Goodrich, L.M., Hambro, E. and Simon, A.P., The Charter of the United Nations, 3rd edn. (1969) pp. 6667Google Scholar; Mosler, loc. cit. n. 64, at pp. 136 et seq.; Conforti, B., ‘The Principle of Non-Intervention’, in Bedpoui, M., ed., International Law: Achievements and Prospects (1991) p. 467.Google Scholar

69. See for the ascription of a similar role to general principles, Lammers (loc. cit n. 32, at pp. 68–69, and 72), who draws a distinction between these ‘principles resting on expressed general legal conviction or principles obtained through induction’ and ‘customary international law proper’. However, for reasons similar to those given here, he concedes that the conflation of the two categories ‘is not incomprehensible’. See also Cassese, loc. cit. n. 1, at p. 174, and Brownlie, loc. cit. n. 9, at p. 19 for a similar characterisation. Brownlie actually treats the category ‘general principles of law’ separately from the category ‘general principles of international law’. The latter category, he says, ‘may refer to customary law, general principles of law as in Art. 38 (1)(c), or to logical propositions resulting from judicial reasoning on the basis of existing pieces of international law and municipal analogies. What is clear is the inappropriateness of a rigid categorization of the sources.’

70. Schachter, loc. cit. n. 7, at pp. 53–54. See also Mosler, loc. cit. n. 64, at p. 134.

71. See similarly, Brownlie, loc. cit. n. 9, at p. 16: ‘… it is impossible, or at least difficult, for state practice to evolve the rules of procedure and evidence which tribunals must employ.’

72. Lloyds & Scottish Finance Ltd v. Williamson [1965] 1 WLR p. 404.

73. Sale of Goods Act (1979), section 22(1), abolished by Sale of Goods (Amendment) Act, section 1.

74. Sale of Goods Act (1979), section 23.

75. See Guisan, F., La Protection de l'Acquéreur de Bonne Foi (1970), esp. Chap. 1 and 2.Google Scholar

76. [1949] 1 KB 322, at pp. 336–337.

77. See Jennings and Watts, loc. cit. n. 44, at pp. 1284–1309, for a discussion of the practice regarding the discharge of treaty obligations. Quite distinct from the scope of the rule is the question of its basis. Jennings and Watts state that ‘[t]he question why international treaties have binding force has been much disputed. The correct answer is probably that treaties are legally binding because there exists a customary rule of international law that treaties are binding …’ (at p. 1206; our emphasis); so much for the ‘logical’ basis of the principle.

78. The constitutional question of the ability of the United Kingdom Parliament to bind future Parliaments provides an illustration of this point. The rule chosen by the English courts is that of ‘implied repeal’, namely that a later Act of Parliament prevails over an earlier one because it is the implicit intention of Parliament in the later Act to repeal the earlier one (Ellen Street Estates Ltd v. Minister of Health [1934] KB 590, at p. 597), which is a reflection of the principles under consideration. But the fact that this is only a legal rule rather than a logical rule is to be seen when the applicability of the EEC Treaty has been in issue. In Litster v. Forth Dry Dock Co Ltd [1990] 1 AC 546, the House of Lords was prepared to construe the words of a contrary domestic statute to conform with EEC law, whereas in Duke v. GEC Reliance Ltd [1988] AC 618, Lord Templeman held that die words of a statute passed in 1975 before the conflicting relevant EEC Council Directive of 1976 could not be construed so as to conform with the Directive, so that the intention of Parliament cannot have been that the EEC rule prevail over the domestic Act. There is nothing which stops the English courts, however, from choosing to apply the European law on the basis that sections 2 and 3 of the European Communities Act 1972, another, earlier Act of Parliament, could be read as having expressed Parliament's will that European law should prevail over domestic Acts. That this is so is confirmed by the House of Lords decision in Webb v. EMO ([1995] 4 All ER 577), where, in circumstances identical to those in the Duke case, the House of Lords read the domestic Act to conform with the meaning of the European law as construed by the European Court of Justice. In sum, the reference to the ‘logical’ lex posterior and lex specialis rules were not a solution to this problem, as different judges in three different cases reached these different results on the same legal question. A legal rule, be it ‘logical’ or otherwise, applies only after the characterisation of the factual circumstances. No ‘logic’ can guarantee, in advance, the applicability of a legal rule.

79. Schachter, loc. cit. n. 7, p. 54. See also Tunkin, loc. cit. n. 4, at p. 200 et seq., and Virally, M., ‘Le rôle des “principes” dans le développement du droit international’, Recueil en hommage á Paul Guggenheim (1968) p. 531.Google Scholar

80. ICJ Rep. (1986) p. 554.

81. Ibid., at p. 566, para. 23.

82. Thirlway, H., ‘The Law and Procedure of the International Court of Justice: Part One’, 60 BYIL (1989) p. 106Google Scholar. See also Judge Bedjaoui's Dissenting Opinion in the Guinea Bissau-Senegal case, 83 ILR(1992), p. 1.Google Scholar

83. See pp. 566–567 of the judgment.

84. Organisation of African Unity, AGH/ Res. 16 (I), 1964.

85. See Brownlie, loc. cit. n. 9, giving several examples, states at p. 135 that it must be emphasised that the principle ‘is by no means mandatory and the states concerned are free to adopt other principles as the basis of the settlement. However, the general principle … is in accordance with good policy [i.e., not logic] and has been adopted by governments and tribunals concerned with boundaries in Asia and Africa.’ See also the North Sea Continental Shelf cases, loc. cit. n. 12, at pp. 28–37, paras. 37–59, where the Court found that the argument that the notion of equidistance ‘as being logically necessary, in the sense of being an inescapable a priori accompaniment of basic continental shelf doctrine, was incorrect’, contrary to the views of the two Kingdoms and Judge Tanaka (at p. 181).

86. See the celebrated paper by Dewey, J., ‘Logical Method and Law’, 10 Cornell LQ (1924) pp. 1727.Google Scholar

87. Schachter, loc. cit. n. 7, p. 54. The same argument can be applied to Fitzmaurice's often quoted statement that ‘A rule answers the question “what”: a principle in effect answers the question “why” (‘The General Principles of International Law Considered from the Standpoint of the Rule of Law’, 92 Hague Recueil (1957-II), p. 1 at p. 7Google Scholar; a principle, however described, and whether it is distinguishable from a rule in this manner or not, must be a well-recognised principle.

88. Szasz, P., ‘General Law-Making Processes’, in United Nations Legal Order, Schachter, O. and Joyner, C., eds., Vol. 1 (1995) p. 35 at pp. 4445Google Scholar. See also Simma, B. and Alston, P., ‘The Sources of Human Rights Law: Custom, Jus Cogens, and General Principles’, 12 Australian YIL (1992) p. 82Google Scholar; Lammers, loc. cit. n. 32, at p. 58 (discussing the views of Verdross and Simma), and p. 72 (referring to principles of international law which are not customary because they do not enjoy the support of actual State practice); Cassese, loc. cit. n. 1, at p. 174, para. 94.

89. See e.g., Szasz and Simma and Alston, loc. cit. n. 88, who argue for this approach as a way of protecting human rights.

90. Szasz, loc. cit. n. 88, at p. 43.

91. See Akehurst, M., ‘Custom as a Source of International Law’, 47 BYIL (1974-1975) p. 1 at pp. 18Google Scholar, for devastating criticism of views which limit state practice to physical acts and not claims. The main proponents of such views are A. D'Amato, loc. cit. n 21, Judge Read in the Anglo-Norwegian Fisheries case, ICJ Rep. (1951) p. 116 at p. 191Google Scholar, and, less extremely, Thirlway, H.W.A., International Customary Law and Codification (1972) p. 58.Google Scholar

92. ICJ Rep. (1986) p. 14, e.g. at p. 102–3 (para. 193), pp. 106–108 (para. 202–5). See also the Court's Advisory Opinion on the Legality of the Threat or Use of Nuclear Weapons, ICJ Rep. (1996) especially the Opinions of Judge Schwebel (at p. 6 thereof) and Judge Oda (at. pp. 15–42).

93. See Higgins, R., Problems and Process: International and How We Use It (1994) pp. 1828Google Scholar, especially p. 20; her argument proceeds on the assumption that torture is prohibited under customary law.

94. Akehurst, loc. cit. n. 91, pp. 12–15, at p. 14.

95. See text accompanying nn. 34–36 above, and accompanying text. The International Court stated in the South-West Africa cases (ICJ Rep. (1966) p. 5, at p. 34Google Scholar, para. 49, that: ‘Throughout this case it has been suggested, directly or indirectly, that humanitarian considerations are sufficient in themselves to generate legal rights and obligations, and that the Court can and should proceed accordingly. The Court does not think so. It is a court of law, and can take account of moral principles only in so far as these are given sufficient expression in legal form. Law exists, it is said, to serve a social need; but precisely for that reason, it can do so only through and within the limits of its own discipline. Otherwise, it would not be a legal service that would be rendered.’

96. See e.g., Judge Wellington Koo's Separate Opinion in the Right of Passage case (ICJ Rep. (1960) pp. 66–7), where he stated that the basis upon which municipal law could be adapted for use in international law was ‘the principle of justice founded on reason’; Judge Tanaka's Dissenting Opinion in the South-West Africa cases (idem., at p. 296 et seq.), where he refers to the jus rationale.

97. See Schachter, loc. cit. n. 7, at p. 55.

98. See e.g., Tesón, F., Humanitarian Intervention: An Inquiry Into Law and Morality (1988)Google Scholar and Henkin, loc. cit. n. 4, Part Two.

99. See Waluchow, W. J., Inclusive Legal Positivism (1994)Google Scholar, and the review of this book by Lim, C. L., ‘A Re-Appraisal of the Limits of Legal Positivism; The Case for Morals of Pedigree’, 14 Legal Studies (1994) p. 446CrossRefGoogle Scholar. An example of this ‘value-inclusive’ positivism is provided by Arts. 5 and 6 of the International Law Commission's Draft Articles on the Law of Non-Navigational Uses of International Watercourses, which set out (a non-exhaustive list of) the factors to be taken into account in ensuring the equitable utilization of watercourses (see 24 EPL (1994) p. 335 et seq.). Other examples of the positive laws requiring the application of equity abound, and are further examples; see, e.g., Article 59, 74 and 140 of the 1982 United Nations Law of the Sea Convention (UN Doc. A/CONF. 62/122; 21 ILM (1982) p. 1261); and see the Gulf of Maine case, ICJ Rep. (1984) p. 244, at pp. 288295Google Scholar, paras. 79–96.

100. See further Finnis, J.M., Natural Law and Natural Rights (1980) at pp. 3642 and 63Google Scholar, and McCormick, N., ‘Natural Law Revisited’, 1 Oxford Journal of Legal Studies (1981) p. 99.CrossRefGoogle Scholar

101. Loc. cit. n. 12, at p. 50.

102. Lowe, V., ‘The Role of Equity in International Law’, 12 Australian YIL (1992) p. 54, pp. 7073, at p. 72.Google Scholar

103. See the often-cited judgment of Judge Hudson in the Diversion of Water from the River Meuse case (PCIJ Rep. Series A/B, No. 70, pp. 76–77 (‘Article 38(1)(c) expressly directs the application of “general principles of law recognised by civilised nations,” and in more than one nation, principles of equity have an established place in the legal system.’ See also Judge Ammoun's Separate Opinion in the North Sea cases, loc. cit. n. 12, e.g., at p. 136 et seq. These suggest general principles of municipal law as the basis of equity, and these principles have been discussed in subsection 2.1. Also, the point made in the text following n. 95 above suggest that equity may have a role to play in the context of inchoate custom, for which see subsection 2.4. Also, in the Frontier Dispute case, loc. cit. n. 80, where the Republic of Mali urged the application of ‘that form of equity which is inseparable from the application of international law’ (see p. 567, para. 27 of the judgment). This may be taken to mean that equity is a necessary part of law in general or of international law specifically, in which case, see sub-sections. 2.2 and 2.3.

104. See Lowe, loc. cit. n. 102, at pp. 56–67.

105. This is the definition used by the Chamber in the Frontier Dispute case, loc. cit. n. 80, at. pp. 567–568.

106. Judge Gros, in the Gulf of Maine case (ICJ Rep. (1984) p. 244, at p. 384, para. 40)Google Scholar, referring to the Barcelona Traction case (loc. cit. n. 70, at paras. 92–102), stated that ‘the Court again took the traditional prudent approach and, following several considerations relating to the case, ruled out the application of equity, though saying that “as in other fields of international law, it is necessary that the law be applied reasonably” (para. 93), which does not go very far, and more or less amounts to the assimilation of the equitable to the reasonable…’

107. This is the definition used by Akehurst, loc. cit. n. 59, at p. 801.

108. See Judge Fitzmaurice's Separate Opinion in the Barcelona Traction case (loc. cit. n. 70, at pp. 85–86, para. 36), where he quoted the then current edition of Snell's Principles of Equity for the proposition that ‘equity is not distinguishable from law “because it seeks a different end, for both aim at justice…”’.

109. This term is used by Hart, loc. cit. n. 10.

110. Ibid.

111. Lowe, loc. cit. n. 102, at p. 59, uses the Corfu Channel case (ICJ Rep. (1949) at p. 22) as an illustration. In relation to the obligation of Albania to warn British ships of mines in the Channel, the Court chose to refer, inter alia, to ‘elementary considerations of humanity’, which some writers (e.g., Akehurst, loc. cit. n. 59, at p. 806) have taken, rightly or wrongly, to mean a reference to equity, as a basis for the existence of such an obligation. Lowe points out that the Court could have referred to other rules of customary law in order to ground the same obligation; for example, the rules that (a) ‘coastal States may put no obstacles in the way of the innocent passage of foreign vessels in the territorial sea’, or that (b) ‘States are responsible if an injury to an alien results from an act, committed within its territory, which is attributable to another State if it has failed to use due diligence to prevent such injury. Even if such rules had not previously been construed to include an obligation to warn foreign ships, they could legitimately have been construed in such a manner.’ He also uses another illustration of the unlimited nature of the process of inference, taken from the law of jurisdiction: ‘… if state practice contains many instances of uncontested assertions of jurisdiction over aliens in cases of cross-frontier shooting and blackmail cases, is it proper to infer a rule allowing “objective” territorial jurisdiction only in relation to such crimes? or in relation to those and similar crimes such as fraud? or in relation to all generally recognised crimes where physical acts take place in the two jurisdictions? or to any such crime under the law of the State claiming jurisdiction, no matter how idiosyncratic …? or to all crimes which produce an effect within the state …? or to all crimes injuring the interests of the state, or of its nationals? … There is no rational basis upon which any formulation of a rule inferred from State practice can be said to constitute an “improper” inference of a rule from that practice, although there may be considerations of principle orpublic policy external to the process of inference which render one interpretation preferable to another.’

112. As Sir Gerald Fitzmaurice (quoted by Lowe, loc. cit. n. 102, at p. 61, taken from his ‘Judicial Innovation – Its Uses and Perils – As Exemplified in Some of the Work of the International Court of Justice During Lord McNair's Period of Office’, in Cambridge Essays in International Law: Essays in Honour ofLord McNair (1965) p. 24, at pp. 2425)Google Scholar has put it, in practice, ‘courts hardly ever admit a non-liquet. As is well known, they adapt existing principles to meet new facts or situations. If none serves, they in effect propound new ones by appealing to some antecedent or more fundamental concept, or by invoking doctrines in the light of which an essentially innovatory process can be carried out against a background of received legal precepts.’

113. Schachter, loc. cit. n. 7, at p. 59.

114. See the Continental Shelf cast (Libya/Malta) (ICJ Rep. (1985) p. 55, para. 76. Apparently, those principles were listed at pp. 39–40, para. 46.

115. Sir Jennings, R., ‘Equity and Equitable Principles’, 42 ASDI (1986) p. 27, at p. 38.Google Scholar

116. See Nelson, L.D.M., ‘The Roles of Equity in the Delimitation of Maritime Boundaries’, 84 AJIL (1990) p. 837, at pp. 851853.CrossRefGoogle Scholar

117. ICJ Rep. (1982), p. 18, para. 70.

118. See Ibid., the Dissenting Opinions of Judge Gros at pp. 151–153, paras. 16–18;Judge Oda, at p. 157, para. 1, and p. 269, para. 180; Judge ad hoc Evensen, p. 293–296, para. 14.

119. Loc. cit. n. 117, at p. 360 et seq..

120. See Schachter, pp. 55–61, (‘The Diverse Manifestations of Equity’) for a discussion of the use of equity in State practice outside the context of tribunals. He concludes that equity and distributive justice ‘enter into the arrangements and the negotiations because each régime [in which equity is referred] requires an understanding as to the allocation of benefits and burdens and such allocation must take into account the perceptions of the parties as to fairness and equities of the arrangement. This does not mean that all such arrangements are equitable by some objective standard or that they entirely satisfy each participant as to its fair share. What it does mean is that as a minimum, a participant State must not consider that the co-operative arrangement is so inequitable that it cannot be accepted.’ This seems very close to the normal techniques of negotiation and consensus which are familiar to international law-making. Does the content of equity in everyday practice outside third-party fora, then, differ from what States consent to, just like treaties and custom?

121. See the Dissenting Opinion of Judge Gros in the Gulf of Maine case, loc. cit. n. 100, at p. 386, para. 42: ‘… since equity is now a matter of each judge's opinion, I do not maintain that the Chamber's line, or any of the lines presented during this case, is less equitable than the presented by myself…’. The added emphasis is to show that States do have their own perceptions of what equity demands.

122. The literature on the question of ‘soft’ law, again, is extensive. The following is a representative selection: Bothe, M., ‘Legal and Non-legal Norms – A Meaningful Distinction in International Relations?’, 11 NYIL (1980) p. 91CrossRefGoogle Scholar; Cassese and Weiler, loc. cit. n. 3; Gruchalla-Wesierski, T., ‘A Framework for Understanding “Soft Law”’, 30 McGill LJ (1984) p. 37Google Scholar; Wellens, K. C. and Borchardt, G. M., ‘Soft Law in European Community Law’, 14 ELR (1989) p. 267Google Scholar; Chinkin, C., ‘The Challenge of Soft Law: Development and Change in International Law’, 38 ICLQ (1989) p. 850CrossRefGoogle Scholar; Handl, G., ‘Environmental Security and Global Change’, 1 YIEL (1990) p. 3Google Scholar; Koskenniemi, M., ‘Breach of Treaty or Non-Compliance? Reflections on the Enforcement of the Montreal Protocol’, 3 YIEL (1992) p. 123Google Scholar; Fitzmaurice, M. A., ‘International Environmental Law as a Special Field’, 25 NYIL (1994) p. 181, pp. 199201CrossRefGoogle Scholar; Sands, P., ‘International Law in the Field of Sustainable Development: Emerging Legal Principles’, in Lang, W., ed.. Sustainable Development and International Law (1995) p. 53.Google Scholar

123. See e.g., M. Virally's contribution in Cassese and Weiler, loc. cit. n. 3, pp. 72–73 at p. 73.

124. Of course, the same applies even where the norm in question is not one which is concerned with global values, but is simply a norm concerned with State values, but where there is a lack of common ground upon which to base ‘hard’ obligations.

125. See G. Arangio-Ruiz' warning in Cassese and Weiler, loc. cit. n. 3, at pp. 83–84, to the effect that lawyers should be wary and critical of ‘soft’ law because it is often used as a political technique by States to create the impression that something useful had been done to regulate important social issues.

126. Loc. cit. n. 92. For a discussion of the controversial nature of the judgment, see Charlesworth, H., ‘Customary International Law in the Nicaragua Case’, 11 Australian YIL (1991) p. 1.Google Scholar

127. See for criticism of the judgment, D'Amato, A., ‘Trashing Customary International Law’, 81 AJIL(1987) p. 101CrossRefGoogle Scholar, and Mendelson, M., ‘The Nicaragua Case and Customary International Law’, 26 Co-existence (1989) p. 85.Google Scholar

128. See Borchardt and Wellens, loc. cit. n. 122, for analysis of the important role of the intentions of the parties in this context.

Full text views

Full text views reflects PDF downloads, PDFs sent to Google Drive, Dropbox and Kindle and HTML full text views.

Total number of HTML views: 0
Total number of PDF views: 374 *
View data table for this chart

* Views captured on Cambridge Core between September 2016 - 23rd January 2021. This data will be updated every 24 hours.

Hostname: page-component-76cb886bbf-rm8z7 Total loading time: 0.437 Render date: 2021-01-23T05:30:25.036Z Query parameters: { "hasAccess": "0", "openAccess": "0", "isLogged": "0", "lang": "en" } Feature Flags: { "shouldUseShareProductTool": true, "shouldUseHypothesis": true, "isUnsiloEnabled": true, "metricsAbstractViews": false, "figures": false, "newCiteModal": false }

Send article to Kindle

To send this article to your Kindle, first ensure is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle.

Note you can select to send to either the or variations. ‘’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

‘General principles of law’, ‘soft’ law and the identification of international law*
Available formats

Send article to Dropbox

To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Dropbox.

‘General principles of law’, ‘soft’ law and the identification of international law*
Available formats

Send article to Google Drive

To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Google Drive.

‘General principles of law’, ‘soft’ law and the identification of international law*
Available formats

Reply to: Submit a response

Your details

Conflicting interests

Do you have any conflicting interests? *