Sources of International Law - A Reevaluation

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These soft law instruments have, according to Professor Antonio Cassese, three major features in common. First, they are indicative of the modern trends emerging in the world community. Secondly, they deal with matters that reflect new concerns of the international community, to which previously this community was not sensitive or not sufficiently alert. Third, for political, economic, or other reasons, it is, however, hard for States to reach full convergence of views and standards on these matters so as to agree upon legally binding commitments.110

While it may be paradoxical to call something “law” when it is not law, the concept is nonetheless useful to describe instruments that clearly have an impact on international relations and that may later harden into custom111 or become the basis of a treaty.112

6. 3 Equity

Equity is used here in the sense of considerations of ‘fairness’, and ‘reasonableness’. It is the application of rules of international law with due regard to what is fair and reasonable.

In the Diversion of Water from the Meuse case113, the Netherlands claimed that Belgium had violated a treaty by building canals that changed the flow of water in the River Meuse. One of the issues was whether the Netherlands had lost the right to bring the claim because of similar earlier conduct by itself (estoppel). In this connection, the individual opinion of Judge Hudson recognized the principle of ‘equity’ as part of international law. He noticed that there was no express authority in the Statute of the PCIJ to apply equity as distinguished from law. But he pointed to Article 38(1)(c) of the Statute which allowed the application of ‘general principles of law’ and argued that principles of equity are common to all national legal systems.

References to ‘equity’ can be found very often in the judgments of the World Court. Examples include the River Meuse case itself (application of equitable principle of estoppel), the Temple of Preah Vihear case114 (application of acquiescence), Barcelona Traction case115 (reference to “considerations of equity” when seeking to apply the law of diplomatic protection “reasonably”), and the Frontier Dispute case (Burkina Faso v Mali)116 (application of equity infra legem117,that is, that form of equity which constitutes a method of interpretation of the law in force, to territorial delimitation).

Perhaps the most prominent use of equity as part of international law has been in the law of the sea in the context of delimitation of maritime zones. In the Fisheries

110Cassese, Antonio, International Law, Oxford University Press, 2001, 160-1.

111For instance, the University Declaration of Human Rights 1948 was “soft Law” when it was adopted but has since to some extent hardened into custom. See Filartiga v Pena-Irala, 630 F.2d 876 (1980).

112For instance, the United Nations Declaration on Torture 1975, GA Resolution 3452, formed the basis for the later adoption of the Convention Against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment 1984.

113Diversion of Water from the Meuse (Netherlands v Belgium), (1937) PCIJ Series A/B, No. 70.

114Temple of Preah Vihear case, (1962) ICJ Rep. 6.

115Barcelona Traction case (Belgium v Spain), (1970) ICJ Rep. 3, at paras. 93-94.

116Frontier Dispute case (Burkina Faso v Mali), (1986) ICJ Rep. 554.

117See Akehurst, M., “Equity and General Principles of Law”, (1976) 25 ICLQ 801.

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Jurisdiction case118, the Court outlined the elements of an ‘equitable solution’ of the differences over fishing rights and directed the parties to negotiate accordingly. In the North Sea Continental Shelf cases119, the Court had to resort to the formulation of equitable principles concerning the delimitation of adjacent areas of continental shelf, as a consequence of its opinion that no rule of customary or treaty law bound the States parties to the dispute. The Court has increasingly referred to “equity” in its judgments in recent years. For example, in the Gulf of Maine case120, it stated that the concepts of acquiescence and estoppel in international law “follow form the fundamental principles of good faith and equity”.

The conclusion then is that ‘equity’, in the present context, is encompassed by Article 38(1)(c) of the Statute, that is, as a general principle of law, and not by Article 38(2) which empowers the Court to decide a case ex aequo et bono, if the parties agree thereto121.

7 THE HIERARCHY OF THE SOURCES

There is no indication in Article 38 of the Statute of the priority or hierarchy of the sources of international law. Apart from a single reference to ‘subsidiary means’ in Article 38(1)(d), we do not know the order in which the sources of law are to be applied. When drafting the original text of article 38, words of priority were included: “the sources listed should be considered by the Court in the undermentioned order (i.e., the order (a) to (d) in which they now appear)”; but ultimately they were deleted.122 The silence in Article 38 as to a hierarchy of sources reflects accurately the nature of the international legal order in which a hierarchy of sources is an alien concept. Indeed, there is no difficulty if the rules derived from the various sources are complementary. However, in cases of conflict it is vital to determine which source shall prevail. The state of the law relating to the hierarch or priority among the various sources of international law can be summarized as follows:

(1) Jus cogens: the highest in the hierarchy

A rule of jus cogens is a peremptory norm of general international law, which is “a norm accepted and recognized by the international community of States as a whole as a norm from which no derogation is permitted and which can be modified only by a subsequent norm of general international law having the same character”.123 The typical effect of rules of jus cogens is that as States cannot derogate from them

118Fisheries Jurisdiction case (UK v Iceland), (1974) ICJ Rep. 3, at 30-5.

119North Sea Continental Shelf cases, (1969) ICJ Rep. 3, at 46-52.

120Gulf of Maine case, (1984) ICJ Rep. 246, at 305.

121Article 38(2) refers to a decision by the Court where equity overrides all other rules. This is the power of the Court to decide a dispute at the request of the parties without any reference to international law at all. It has never been used by the Court.

122Akehurst, M., “Hierarchy among the Sources of International Law”, (1974-75) 47 BYIL, 273. Professor Harris refers to the oppositions at the meeting of the Advisory Committee of jurists, namely:

(1) if the expression [undermentioned order] only meant that a convention should be considered before, for instance, customary law, it is unnecessary because it is a fundamental principle of law that a special rule goes before general law; (2) This expression also seems to fail to recognise that these various

sources may be applied simultaneously. See Harris, D.J., Cases and Materials on International Law, 5th.ed., 1998, 23.

123See Article 53 of the Vienna Convention on the Law of Treaties 1969.

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through treaties or customary rules (which are not endowed with the same legal force), the treaty or customary rules contrary to them are null and void.124 Therefore, rules having the character of jus cogens are the highest in the hierarchy of the sources of international law.

(2) Treaty versus custom

Our concern here is the interaction between the two major sources of international law: ‘treaty and custom’. They are both necessary components of the international order. Usually, they are quite complementary. A treaty may codify custom or may lead to the development of new customary law through the impetus it gives to State practice. On the other hand, States may abrogate a customary rule by concluding a treaty125; the latter may again be modified by new customary law.126 Therefore, the conclusion is that treaty law and customary law are of equal authority and of equal status (with the exception of the principle of jus cogens).

Difficulties can arise, however, if the treaty and customary law stipulate contradictory or dissimilar obligations. In case of conflict, which law shall prevail? One solution can be found in the principle of lex posterior derogat legi priori (a later law repeals an earlier law). When two rules on the same subject matter differ in their contents, the rule originating later in time shall prevail.127 However, There are some difficulties in the application of this principle: (1) The principle raises the problem of determining the precise moment of the formation of a customary rule; (2) a new particular customary or conventional rule may arise leaving the general one unchanged for the remaining members of the international community or the parties to the multilateral treaty; and (3) in the case of codification of a customary rule, there is no ground for automatic abrogation of an old, well-settled general rule in so far as it does not contradict the codified one.128

In deciding possible conflicts between treaty law and customary law, two other principles must also be observed. The first one is lex specialis derogat legi generalis (A special law prevails over a general law).129 The second one is Lex posterior

124Cassese, Antonio, International Law, 2001, 143.

125One of the main reasons why States make treaties is because they regard the relevant rules of customary law as inadequate. Thus States may derogate from customary law by concluding a treaty with different obligations, the only limitation being rules of jus cogens. See Akehurst’s Modern Introduction to International Law, 1997, 56.

126Treaties can come to an end through ‘desuetude’ –the situation in which the treaty is consistently ignored by one or more parties, with the acquiescence of the other party or parties. Desuetude often takes the form of the emergence of a new rule of customary international law, confliction with the treaty. See Kontou, N., The Termination and Revision of Treaties in the Light of New Customary International Law, 1994.

127Villiger, M.E., Customary International Law and Treaties, Martinus Nijhoff Publishers, Dordrecht, 1985, 36.

128Wolfke, K., Custom in Present International Law, 2nd.rev.ed., Martinus Nijhoff Publishers, Dordrecht, 1993, 114-5.

129Whether a rule is lex specialis or not can be determined ratione personae, that is regarding the number of those that are bound by the rule. In this sense, a rule can be a lex specialis if it binds few States, as opposed to a convention with many parties, or to a general customary rule, which is binding erga omnes. A rule can also be special, ratione materiae, in that it furnishes, in comparison with lex generalis, the deeper, more detailed, perhaps exceptional, regulation on the same subject-matter.

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generalis non derogat legi priori specialis (a later law, general in nature, does not repeal an earlier law which is more special in nature).130

(3) Inconsistent treaties

If there are successive treaties relating to the same subject matter, which treaty shall prevail? The answer can be found in Article 30 of the Vienna Convention on the Law of Treaties 1969, which is to be applied subject to Article 103 of the United Nations Charter.131 The essence of Article 30 is that ‘when all the parties to the earlier treaty are parties also to the later treaty, then the general rule of lex posterior derogat legi priori applies and the later treaty shall prevail over the earlier treaty’.132

Article 103 of the Charter: Clause paramount

Article 103 of the Charter reads: “ In the event of a conflict between the obligations of the Members of the United Nations under the present Charter and their obligations under any other international agreements, their obligations under the present charter shall prevail”. This article is known as ‘clause paramount’ and it clearly acknowledges the supremacy of the UN Charter over any other treaties. In the Lockerbie case (Provisional Measures)133, the International Court of Justice confirms this and held that by virtue of Article 103, obligations of the parties under the UN Charter (that is, the SC Resolution 748) prevail over their obligations under the Montreal Convention.

(4) General Principles of Law and Other sources

Since the main function of general principles of law is to fill gaps in treaty law and customary law, it would appear that treaties and custom prevail over general principles of law in the event of conflict. Judicial decisions and learned writers are described in Article 38(1)(d) as ‘subsidiary means for the determination of rules of law’, which suggests that they are subordinate to the other three sources listed: treaties, custom and general principles of law. Judicial decisions usually carry more weight than learned writers, but there is no hard and fast rule; much depend on the quality of the reasoning which the judge or writer employs.

8 CONCLUSION

Custom and treaties constitute the two most important sources of international law. A distinctive feature of international law making is the absence of any hierarchy between custom and treaties as sources of law. They are of equal rank and status.

130See the comment of Ago in the ILC, Yearbook of the ILC, 1966 vol. 1, Part 2, 167, para 50.

131Article 30(1) of the Vienna Convention on the Law of Treaties 1969.

132Article 30(3), Ibid. However, According to Article 30(4),

“When the parties to the later treaty do not include all the parties to the earlier one:

(a)as between States parties to both treaties the same rule applies as in paragraph 3;

(b)as between a State party to both treaties and a State party to only one of the treaties, the treaty to which both States are parties governs their mutual rights and obligations.”

133Case Concerning Questions of Interpretation and Application of the 1971 Montreal Convention arising from the Aerial Incident at Lockerbie (Libya v UK) (Libya v United States), (1992) ICJ Rep. 3,

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Nevertheless, in recent years, a new category of international rules has come into being: jus cogens or peremptory norms of general international law. States may not derogate from jus cogens through treaties or customary rules. It follows that jus cogens is hierarchically superior to all the other rules of international law.

Having said that, we can now summarise the main points on the application of the sources of international law.

(1)If there is a treaty binding the two parties to a dispute, it is quite logical that the Court will, first of all, look at the treaty, which is a jus scriptum. Even in such a situation, however, we cannot say that customary law is entirely irrelevant. There may be quite a number of legal issues involved in the dispute. The treaty cannot have solutions to all of them. The Court, unavoidably, has to apply customary law to deal with issues in respect of which there are no answers in the treaty. In a number of cases, the Court will need to apply customary law to interpret the provisions of the treaty. Therefore, it appears that the Court in most cases apply both treaty law and customary law simultaneously.

(2)If there is no treaty binding the two parties to a dispute, then the Court has to rely exclusively on customary international law for the determination of the dispute.

(3)If no relevant rule can be found in treaty law and customary law, the Court may apply the general principles of law accepted by most national legal systems. ‘Equity’ is applied by the Court as a general principle of law.

(4)Judicial decisions and writings of publicists are subsidiary means for the determination of the rules of law. Judicial decisions appear to have more weight. Even though in theory there is no doctrine of binding precedent in international law, in practice the Court always refer to its previous decisions and has established its jurisprudence.

(5)Judicial decisions, resolutions of the General Assembly, national legislation, and the like are the material sources of international law and they can be the evidence of customary law.