Sources of International Law - A Reevaluation

SOURCES OF

INTERNATIONAL LAW: A RE-EVALUATION

By

ABDUL GHAFUR HAMID @ KHIN MAUNG SEIN

Associate Professor

Ahmad Ibrahim Kulliyyah of Laws

International Islamic University Malaysia

IIUM Law Journal

Vol. 11, No. 2 (2003) 203-240

2

SOURCES OF INTERNATIONAL LAW:

A RE-EVALUATION

ABDUL GHAFUR HAMID @ KHIN MAUNG SEIN 1

ABSTRACT

The changes in international community since 1945 have led to fundamental disputes on the sources of international law and it must be admitted that they have become an area of considerable4 theoretical controversy. In particular, the two traditional sources, custom and treaty, are now often difficult to distinguish clearly. The present paper attempts to clearly identify the interaction between the two main sources, namely customary law and treaty law, and clarify the controversy relating to the hierarchy among the sources of international law. The writer finds that custom and treaties are still the primary sources of international law and that there is no hierarchy between them: they are of equal status. In recent years, however, a new category of international rules, jus cogens, has come into being, which is hierarchically superior to all the other rules of international law. The writer suggests that between treaty law and customary law, the practice is that if there is a treaty binding the two parties to a dispute, 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. The Court in most cases applies both treaty law and customary law simultaneously so that it can deal with all the legal issues involved in the dispute. 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. If no relevant rule can be found in treaty law and custom, then the court may apply the general principles of law. The other sources are merely secondary or material sources and most of them can be used as evidence of customary law.

1. INTRODUCTION

In every legal system there must be some criteria by which legal norms or ‘laws’ are recognized. It must have reasonably clear ‘sources of law’. Generally speaking, these sources of law are either ‘law creating’ or ‘law identifying’. That is why writers usually distinguish the ‘formal sources’ and the ‘material sources’ of law.2 According to Salmond, “A formal source is that from which a rule of law derives its force and validity…. The material sources, on the other hand, are those from which is derived the matter, not the validity, of the law. The material source supplies the substance of the rule to which the formal source gives the force and nature of law”. 3 Simply put, a

International Islamic University Malaysia. I am greatly indebted to the Research Centre, International Islamic University Malaysia, for funding this research.

2 See, Brownlie, Ian, Principles of Public International Law, 5th.ed., 1998, 1; Schwarzenberger, Georg, International Law, vol. 1, 3rd.ed., 1957, 26-27; Hart, H.L.A., The Concept of Law, 1961, 246-7. However, Professor Brownlie is of the following view: In the context of international relations, the use of the term ‘formal source’ is misleading because there is no constitutional machinery of law-making in the creation of rules of international law. Brownlie, op. cit., 2.

3Salmond, J.W., Jurisprudence, 7th.ed., 1924, para. 24.

3

formal source represents the mechanism through which the law comes into being, whereas a material source indicates where the legal rules come from, that is, where the rules are located. In other words, the function of a formal source is ‘law creating’ whereas the function of a material source is ‘law identifying’.

Where do international lawyers look to find international law? There are, in the context of international law, recognized and accepted methods by which legal rules come into existence (formal sources) as well as several ways in which the precise content of legal rules can be identified (material sources)4. These are the sources of international law.

The most important source of international law for centuries was customary law, evolving from the practice of States.5 The recent attempts to codify international law and the conclusion of multilateral treaties in many important areas have sought to clarify the law and to establish universally accepted norms. But customary law has still retained its predominance over treaty law or other sources in many other areas, such as, for example, State immunity or State responsibility. The changes in international community since 1945 have led to fundamental disputes on the sources of international law and it must be admitted that they have become an area of considerable theoretical controversy. In particular, the two main traditional sources, custom and treaty, are now often difficult to distinguish clearly.6 The main objectives of the present paper, therefore, are to clearly identify the interaction between the two main sources, namely customary law and treaty law, and to clarify the controversy relating to the hierarchy among the sources of international law.

2 STATUTE OF THE INTERNATIONAL COURT OF JUSTICE

Article 38 of the Statute of the International Court of Justice is always the starting point for any study of the sources of international law.

Article 38

1.The Court, whose function is to decide in accordance with international law such disputes as are submitted to it, shall apply:

(a)International conventions, whether general or particular, establishing rules recognized by the contesting States;

(b)International custom, as evidence of a general practice accepted as law;

(c)The general principles of law recognized by civilized nations;

(d)Subject to the provisions of article 59, judicial decisions and the teachings of the most highly qualified publicists of the various nations, as subsidiary means for the determination of the rule of law.

2.This provision shall not prejudice the power of the Court to decide a case ex aequo et bono, if the parties agree thereto.

formal source of international law, and its substance will be indicated by State practice, which is the

there has never been a time when there has been so much confusion and doubt about the tests of the validity – or sources – of international law, than the present”. See Jennings, R., “What is International Law and How Do We Tell When We See It?” (1981) 37 ASDI, 59-88.

4

These provisions are expressed in terms of the function of the Court, but they represent the previous practice of arbitral tribunals, and are generally regarded as an authoritative statement of the sources of international law.7 Some writers have criticized the Article on the ground that it does not list all the sources of international law, or that it includes aspects which are not genuine sources, but none of the alternative lists which have been suggested has won general approval.8 It is therefore proposed to examine the sources listed in the Court’s Statute before considering other possible sources of international law.

3 TREATIES

Article 38 (1) (a) of the Statute of the International Court of Justice requires the Court to apply “international conventions, whether general or particular, establishing rules expressly recognized by the contesting States”. The word ‘convention’ means a treaty and whatever the nomenclature is9, the substance is the same: it is an agreement made between two or more States or other subjects of international law.

3. 1 Treaty as a source of international law

A treaty is based on consent. Such consent may be expressed by one of the accepted methods (signature, ratification, accession, etc.). Once a treaty has entered into force, it is binding on the parties to it. By virtue of the maxim pacta sunt servanda, States parties shall perform the treaty in good faith. In other words, the treaty is the law for the parties. Failure to comply with the terms of a binding treaty will incur international responsibility unless a defence is available.10

Being based on consent, the general principle is that only the parties to a treaty are bound by its terms. As the Permanent Court of International Justice in 1926 put it in

Certain German Interests in Polish Upper Silesia, “a treaty only creates law as between the States which are parties to it’11. Hence, for third States treaties are something devoid of any legal consequence: they are a thing made by others (res inter alios acta). To put it differently, a treaty may not impose obligations or confer rights on a third party. This is often expressed in terms of the Latin maxim pacta tertiis nec nocent nec prosunt. This general principle is now stated in Article 34 of the Vienna Convention on the Law of Treaties, 1969, which reads: “A treaty does not create either obligations or rights for a third State without its consent”.12

7 Akehurst’s Modern Introduction to International Law, 7th. Revised Ed., 1997, 36. Brownlie, Principles of Public International Law, 5th.ed., 1998, 3.

38. On the practice of the Court, see Mendelson, M., “The International Court of Justice and the

10Case Concerning Gabcikovo – Nagymaros Project (Hungary v Slovakia) (1998) 37 ILM 162 (Danube Dam Case).

11Certain German Interests in Polish Upper Silesia, (1926) PCIJ Series A. no. 7. at 29.

12There are a number of exceptions to this general rule:

(1)It is recognized that there is a distinct category of ‘dispositive treaties’ that create an objective legal regime binding upon third States. See Case Concerning Kasikili/Sedudu Island (Boswana v Namibia), ICJ Judgment of 13 December 1999. For s discussion see

5

Law-making treaties and treaty-contracts

Some writers have tried to argue that treaties should be regarded as sources of international law only if they resemble domestic law statutes in content; that is to say, only if they are the so-called ‘law-making treaties’. A law-making treaty has been defined as a treaty concluded by a substantial number of States and stipulates new general rules for future international conduct or abolishes, modifies or codifies existing customary or conventional rules of a general character.13 According to this theory, the so-called ‘treaty-contracts’, on the other hand, are treaties between two or only a few States, dealing with a special matter concerning these States exclusively. These treaties (for instance, a treaty whereby one State agrees to lend a certain sum of money to another State) resemble contracts in domestic law and are not a source of international law but are merely legal transactions.

We cannot accept such an idea. It is too vague and imprecise to justify regarding lawmaking treaties as the only treaties, which are a source of international law. The socalled treaty-contracts may, as between the parties thereto, constitute particular law. That is why the expression ‘general or particular conventions’ is used in Article 38(1) of the Statute. Moreover, even bilateral treaties may provide evidence of customary rules.14 The better view, therefore, is to regard all treaties as a source of law.15

3. 2 Interaction between treaty law and customary law

Customary international law derives from the practice of States. It is by nature slow in its law-making process. There is lack of precision in customary rules, and it is very often quite difficult to ascertain their exact contents. On the other hand, treaty-making process is relatively faster. States may enter into a treaty at any time when they feel that a new rule is required. Treaties are the only way by which international law can be made by a deliberate act of States. In this way treaties are contributing to the rapid expansion of international law.16 Since treaty law is a kind of written law (jus scriptum), it possesses the merit of considerable precision. It is not surprising, therefore, that treaties are fast becoming the most important source of international law.

Treaty as a material source of customary law

North Sea Continental Shelf cases17 are concerned with the role of multilateral treaties as State practice and hence as a material source of customary international law

Shaw, Malcolm, (2000) 49 ICLQ 964.

(2) A multilateral treaty declaratory of existing customary international law will have effect upon non-parties; however, in this instance, the non-party is bound not by the treaty but by the customary rule. See, O’Brien, John, International Law, Cavendish Publishing Ltd., London, 2001, 331.

13See, McNair, The Law of Treaties, Clarendon Press, Oxford, 1961, 5, 124.

14Brownlie, Principles of Public International Law, 5th.ed., 1998, 13.

15Akehurst’s Modern Introduction to International Law, 7th.ed., 1997, 38.

16One of the most significant changes in international law has been the growth in the volume of treaties. The evidence can be seen in the United Nations Treaty Series. Since 1945 over 30,000 treaties have been registered with the United Nations.

17(1969) ICJ Rep. 3.

7

4. INTERNATIONAL CUSTOM

The second source of international law listed in the Statute of the International Court of Justice is ‘international custom’19. Article 38 (1)(b) refers to “international custom, as evidence of a general practice accepted as law”.20 As confirmed by the International Court of Justice in the Nicaragua case21, international custom is constituted by two elements: (1) the objective one of ‘a general practice’; and (2) the subjective one ‘accepted as law’, the so-called opinio juris. In the Continental Shelf (Libya v Malta) case22, the Court stated that the ‘substance of customary international law must be looked for primarily in the actual practice and opinio juris of States’. This is the established doctrine, accepted by States, international tribunals and most writers alike.

4.1 State Practice

The formation of a customary rule requires a general and consistent State practice. Then what acts constitute State practice? Generally speaking, the actual words and actions and omissions of States constitute State practice.

4.1.1 Meaning of State practice: What States do and what States say

It is sometimes suggested that State practice consists only of what States do, not of what they say. For instance, in his dissenting opinion in the Fisheries case, Judge Read argued that claims made to areas of the sea by a State could not create a customary rule unless such claims were enforced against foreign ships.23 But in the later Fisheries Jurisdiction case ten of the fourteen judges inferred the existence of customary rules from such claims, without considering whether they had been enforced.24 The better view therefore appears to be that State practice consists not only of what States do, but also of what they say.

State practice also includes omissions; many rules of international law forbid States to do certain acts.25 Even silence on the part of States is relevant because passiveness and inaction with respect to claims of other States can produce a binding effect creating legal obligations for the silent State under the doctrine of ‘acquiescence’.26

19Although occasionally the terms are used interchangeably, ‘custom’ and ‘usage’ have different meanings. A usage is a general practice, which does not reflect a legal obligation, and examples are ceremonial salutes at sea and the practice of exempting diplomatic vehicles from parking prohibitions.

20On international custom generally see, Akehurst, M., “Custom as a Source of International Law”, (1974-75) 47 BYIL 1; Danilenko, G.M., “The Theory of International Customary Law” (1988) 31 GYIL 9; Kirchner, J., “Thoughts about the Methodology of Customary International Law”, (1992) 43 AJPIL, 215-39; Wolfke, K., “Some Persistent Controversies regarding Customary International Law” (1993)

24NYIL, 1-16; Meron, “The Continuing Role of Custom in the Formation of International Humanitarian Law”, (1996) 90 AJIL, 238-49.

21Military and Paramilitary Activities in and against Nicaragua (Nicaragua v US), (1986) ICJ Rep.

14at 97.

22Continental Shelf (Libya v Malta) case, (1985) ICJ Rep. 29.

23Anglo-Norwegian Fisheries case, (1951) IC J Rep. 116, at 191.

24Fisheries Jurisdiction case (United Kingdom v Iceland) (1974) IC J Rep. 3, at 47

25Article 2, The ILC’s Draft Articles on the Responsibility of States, 2001.

26Akehurst’s Modern Introduction to International Law, 7th.ed., 1997, 43.

8

4.1.2Where to look for evidence of State practice; what are the material sources of custom?

The material sources of custom or evidence of State practice can be found in the following27:

(1)Treaties28;

(2)Judicial decisions29;

(3)National legislation30; (4)Diplomatic correspondence31;

(5)Opinions of national legal advisors;

(6)Resolutions relating to legal questions of the General Assembly

(7)Practice of international organizations.

Evidence of customary law may also be found in the writings of international lawyers, and in judgments of national and international tribunals, which are mentioned as subsidiary means for the determination of rules of law in Article 38(1)(d) of the Statute of the International Court of Justice.

3.1.3 Generality of practice

Article 38(1)(b) talks about the ‘general practice accepted as law’.32 Therefore, generality of practice is a requisite in the formation of customary law. In order for a ‘general custom’ (a rule of general customary international law) to develop (as opposed to a ‘local custom’ binding only a few States), the practice must be fairly general. The element of ‘general practice’ refers to the number of States which have to contribute, actively or passively, towards the customary rule. The term ‘general’ would indicate that common and widespread practice among a significant number of States is required. While universal practice is not necessary, practice should be “representative”, at least of all major political and socio-economic systems. Again, the

27The International Law Commission has suggested a non-exhaustive list of the forms that State

practice may take, Yearbook of the ILC, 1950, vol. II, 368-72. The present list is mainly based on the list of the ILC. See also Brownlie, Principles of Public International Law, 5th.ed., 1998, 5.

28Treaties, being the most easily accessible documents to objective analysis as a manifestation of

conduct and of the view of the contracting parties, belong to the most important evidence of customary law. See Wolfke, K., Custom in Present International Law, 2nd. rev. ed., Martinus Nijhoff Publishers, Dordrecht, 1993, 141.

29Decisions of the ICJ are of decisive importance as evidence of customary rules. Even decisions of national courts can help develop certain area of international law. Similar decisions of national courts from a substantial number of States may be an evidence of international custom.

30The term ‘legislation’ is here employed in a comprehensive sense: it embraces the constitutions of States, the enactments of their legislative organs,and the regulations and declarations promulgated by executive and administrative bodies. Obviously they serve as an important store-house of evidence of State practice.

31The diplomatic correspondence between Governments must supply abundant evidence of customary international law . See Yearbook of the ILC, 1950, vol.2, 371.

32‘General practice’ as mentioned in Article 38(1)(b) stands in contrast to Article 38(1)(a) which specks of “conventions….recognised by the contesting States”. In the Fisheries case, the Court stated that: “Although the ten-mile rule has been adopted by certain States both in their national law and in their treaties and conventions, and although certain arbitral decisions have applied it as between these States, other States have adopted a different limit. Consequently, the ten-mile rule has not acquired the authority of a general rule of law”. Anglo-Norwegian Fisheries case (UK v Norway) (1951) ICJ Rep.

9

degree of generality required will vary with the subject matter, so that an onerous customary law obligation may require a more general practice.

Two implications of the generality of practice may be noted. First, the requirement of general practice (together with opinio juris) appears to be an essential prerequisite for a ‘general customary rule’, which is to be binding erga omnes. The International Court of Justice made this point quite clear in the North Sea Continental Shelf cases: “Customary law rules and obligations,…by their very nature, must have equal force for all members of the international community.”33 Secondly, generality of practice both entails and ensures that only one general customary norm emerges on one issue, The available practice on the matter will have to be so widespread that any remaining inconsistent practice will be marginal and without direct legal effect. If State practice is substantially divided and conforms to two or more differing solutions on one issue, it is not sufficiently widespread and cannot amount to a general customary rule; of course, a number of local, regional, or special customs may arise, each regulating the same question in a different manner for different groups of States.

The concept of the generality of practice is subject to important qualifications inherent in the nature of customary law.

(a) The practice of ‘specially affected’ States

In assessing whether a customary rule has come into existence, State practice must include the practice of those States whose interests are ‘specially affected’ by the subject matter of the rule.34 For example, the practice of major maritime powers will have more significance in the formation of rules on the law of the sea than, for example, that of a landlocked State. It is not that some States are necessarily more ‘important’ or more powerful than others; it is rather that some States will be directly affected by certain rules and thus their practice is more significant.

(b) The effect of acquiescence in the formation of international custom

At a time when a particular practice is developing that may crystallize into a rule of customary international law, a State may react in three possible ways: (i) by doing nothing (that is, complete silence or acquiescence); (ii) by objecting to the practice from the outset (that is, the persistent objector); or (iii) by objecting at a later date when the rule has already established as a custom (that is, the subsequent objector).

It would seem that where there has been a widespread and consistent State practice, then silence by others may be interpreted as ‘acquiescence’ in the development of a rule of customary international law. In such a case acceptance of the rule is established by ‘acquiescence’, It is argued that the effect of the wording of Article 38(1)(b) is to create a presumption that all States whether or not they have participated in the practice are presumed to have assented to the rule unless they can demonstrate that they have the status of a persistent objector.35 Therefore, it is not

33North Sea Continental Shelf cases, (1969) ICJ Rep. 38, para 63.

34North Sea Continental Shelf cases, (1969) ICJ Rep., 3, at para 73: “…a very widespread and representative participation in the (1958 Continental Shelf) Convention might suffice of itself, provided it included that of States whose interests were specially affected”, and para. 74.

35O’Brien, John, International Law, Cavendish Publishing Ltd., London, 2001, 76.

10

surprising that once a rule of general customary international law has been established, the rule is binding upon the international community as a whole36, that is, all States (with the exception of a persistent objector State).

(c) The practice of dissenting States

Not all active practice will adhere to a customary rule. States may wish to dissent from such rule. They can do so expressly in their statements or votes37 or by means of protests,38 or impliedly (in the case of positive conduct) by abstaining from practice or adhering to a different practice. Reservations to a treaty may also represent dissent.

The Persistent objector

As a general rule39, no international obligation may be placed on a State without that State’s consent40; this is inherent in the notion of sovereignty. Again, a distinctive feature of customary international law is that since a State practice does not need to receive universal acceptance to be considered a rule of customary law, a State is unable by its own objection to prevent a customary law from coming into existence.

A State, nevertheless, may contract out of a custom in the process of formation. When a State object to a particular practice carried on by other States or adopts a contrary practice, it may not be bound by any evolving customary law. This is known as the concept of ‘persistent objector’.41 A persistently objecting State is not bound by the eventual customary rule if the State fulfils two conditions. First, the objections must have been maintained from the early stages of the rule onwards, up to its formation, and beyond. Secondly, the objections must be maintained consistently.42 Evidence of objection must be clear and there is probably a presumption of acceptance, which is to be rebutted. Whatever the theoretical underpinnings of the principle43, the concept

36Harris, D.J., Cases and Materials on International Law, 5th.ed., 1998, 25, n. 1.

37They played an important part in the Texaco v Libya Arbitration, (1979) 53 ILR 486.

38MacGibbon, “Some Observations on the Part of Protest in International Law”, (1953) BYIL 310.

39The only exception is the concept of ‘jus cogens’. That is why it has been argued that a persistent objector cannot escape being bound by a new rule of customary international law that has the character of jus cogens. See, e.g., Henkin, Louis, International Law: Politics and Values, 1995, 39.

40This is based on the ‘consensual theory’ of international law. In its pure form, this consensual theory or positivist theory stipulates that no international law can be created without the consent of the State, which is to be bound. This theory recognises that a State’s consent may be given in a variety of ways – express in treaties or implied in custom – but essentially the system of international law is based on voluntary self-restriction.

41Colson, David, “How Persistent Must the Persistent Objector Be?” (1986) 61 Washington L. Rev. 957; Stein, T.L., “The Approach of the Different Drummer: The Principle of the Persistent Objector in International Law”, (1985) Harvard JIL, vol. 26, No. 2, 457-482.

42Villiger, Customary International Law and Treaties, Martinus Nijhoff Publishers, Dordrecht, 1985, 14.

43Charney is of the view that the persistent objector rule has no legitimate basis in international legal system; see Charney, J., “The persistent Objector Rule and the Development of Customary international Law”, (1985) 56 BYIL 1. Charney argues: “The rule has attracted the interest of writers even though it is rarely invoked in practice. For the latter reason, among others, the rule is open to serious doubt….The International Court has referred to the persistent objector rule in two judgments (Fisheries case and Asylum case), but only as dicta, and decided the cases on other grounds. Thus State practice and other evidence do not support the existence of the persistent objector rule”; see Charney, J., “Universal International Law”, (1993) 87 AJIL 529, at 538-39.