Sources of international law


The sources of international law are not the same as those in domestic law. The two major sources creating legally binding rules of international law are treaty and custom. In domestic law the question of the source of a rule or law is seldom controversial. Common law systems rely upon statutes and the decisions to be found in court judgments for evidence of the existence of the rule or law; civil law systems rely upon the appropriate legislation or Codes. It is rarely necessary in either system to inquire whether a legal rule is in fact a legal rule and its existence, if not its interpretation, will be uncontroversial. Exceptionally a further question may arise as to the legitimacy of the rule. If it does it will usually concern the status of the rule that might be affected by procedural defects, or be beyond the power of the body that purported to create it. When such a question does arise there are other rules and procedures that allow for the testing of the validity of the rule in question.1 Various authors have described such domestic systems in terms of primary and secondary rules.

The rules that simply govern conduct are the primary rules, while the ‘rules about the rules’ (that is, those used to determine their legitimacy) are said to be secondary. International law presents different problems, which is why all international law textbooks have a section devoted to the question of sources.2 Thus questions relating to the secondary rules are not only more frequent, but also more difficult to resolve. Uncertainty abounds in international law and customary international law is no exception. Not only is there uncertainty surrounding the exact nature of the two elements considered necessary for custom-formation – state practice and opinio juris. We also do not know how custom-formation works. It is not clear what precisely ‘state practice’ is, nor do we know how we can have a belief that something is already law in order to create it. The particular uncertainties of customary international law point directly to systemic uncertainties at a higher level. Without a dominant legal culture and without a written constitution to blind us to other possibilities, not even a pragmatic outlook can save us from uncertainty. However, even where the law is not disputed, it remains an ideal, not real. Law is based on the fiction that it exists.3 1.1. Research Proposal

The researcher in this project aims to analyse the sources of international law and find out whether there exists a hierarchy among the sources.

1.2. Research Questions Whether there exists a hierarchy among the various sources of international law? Hypothesis – Yes. Even though Article 38 of the Statute of the International Court of Justice does not specify the existence of a hierarchy, in practicality there seems to be a hierarchy of sources.

Whether a treaty provision can give rise to customary law and vice-versa? Hypothesis – Yes. Treaty provisions can give rise to customary law and a custom can give rise to a treaty if certain conditions are fulfilled.

Whether the principles of soft law can be equally influential as treaty rules or custom? Hypothesis – No. They are not an influential source of international as they are not binding. 1.3. Research Methodology

The researcher has used the doctrinal method of research relying on books, journals, articles, case laws and e-sources.

1.4. Chapterisation The second chapter contains an analysis of the various sources of law as mentioned in Article 38(1) of the Statute of the International Court of Justice and other sources. The third chapter explains the hierarchy that exists within these sources and expounds the theory of Jus Cogens. This chapter also elucidates upon the concept of soft law and its influence on international law. The fourth and final chapter contains the conclusion.


2.1. Introduction It is generally accepted that the sources of international law are listed in the Article 38(1) of the Statute of the International Court of Justice, which provides that the Court shall apply: a) International conventions, whether general or particular, establishing rules expressly 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 rules of law.4 Article 38 has been criticized for a number of reasons. For example, it treats judicial decisions and the writings of publicists as being of equal importance, when in practice judicial decisions have more weight. Further, it is worded very generally and thus provides little assistance in resolving the issue of a hierarchy of sources. It does not address the issue of a conflict between different sources of law. Another criticism is that it does not reflect the evolution of international law.

Thus, the reference to international principles ‘recognized by civilized nations’ appears today as at best archaic, and at worst insulting.5 Some scholars have drawn a distinction between formal and material sources of international law. But in the opinion of Salmond, this distinction seems inappropriate. A formal source is that from which a rule 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.6 2.2. Treaties

International conventions are generally referred to as treaties. Treaties are written agreements between States that are governed by international law. Treaties are referred to by different names, including agreements, conventions, covenants, protocols and exchanges of notes. If States want to enter into a written agreement that is not intended to be a treaty, they often refer to it as a Memorandum of Understanding and provide that it is not governed by international law. Treaties can be bilateral, multilateral, regional and global.7 The law of treaties is now set out in the 1969 Vienna Convention on the Law of Treaties which contains the basic principles of treaty law, the procedures for how treaties becoming binding and enter into force, the consequences of a breach of treaty, and principles for interpreting treaties. There are two types of treaties – law-making treaties and treaty contracts. Law-making treaties deal with a wide variety of activities. For example, the Red Cross conventions, suppression of slave trade, control of narcotics etc. These are all matters which called urgently for international statute law and where it would have been impossible to rely on the eventual emergence of customary rules.8 Treaty contracts, unlike law-making treaties, are usually concerned to regulate a narrow area of practice between two states. Such treaties may lead to the formation of general international law.9 The basic principle underlying the law of treaties is pacta sunt servanda which means every treaty in force is binding upon the parties to it and must be performed by them in good faith. The other important principle is that treaties are binding only on States parties. They are not binding on third States without their consent. However, it may be possible for some or even most of the provisions of a multilateral, regional or global treaty to become binding on all States as rules of customary international law. There are now global conventions covering most major topics of international law. They are usually adopted at an international conference and opened for signature.

Treaties are sometimes referred to by the place and year of adoption, e.g. the 1969 Vienna Convention. If a State becomes a signatory to such a treaty, it is not bound by the treaty, but it undertakes an obligation to refrain from acts which would defeat the object and purpose of the treaty. A State expresses its consent to be bound by the provisions of a treaty when it deposits an instrument of accession or ratification to the depository of the treaty. If a State is a signatory to an international convention it sends an instrument of ratification. If a State is not a signatory to an international convention but decides to become a party, it sends an instrument of accession. The legal effect of the two documents is the same. A treaty usually enters into force after a certain number of States have expressed their consent to be bound through accession or ratification. Once a State has expressed its consent to be bound and the treaty is in force, it is referred to as a party to the treaty. The general rule is that a treaty shall be interpreted in good faith in accordance with the ordinary meaning to be given to the terms of the treaty in their context and in light of its object and purpose. The preparatory work of the treaty and the circumstances of its conclusion, often called the travaux preparatoires, are a supplementary means of interpretation in the event of ambiguity. 2.3. Custom

International custom – or customary law – is evidence of a general practice accepted as law through a constant and virtually uniform usage among States over a period of time. Rules of customary international law bind all States. The State alleging the existence of a rule of customary law has the burden of proving its existence by showing a consistent and virtually uniform practice among States, including those States specially affected by the rule or having the greatest interest in the matter.10 For example, to examine the practice of States on military uses of outer space, one would look in particular at the practice of States that have activities in space. The ICJ in the Asylum Case: Colombia v. Peru11 described custom as a constant and uniform usage, accepted as law, i.e. those areas of state practice which arise as a result of a belief by states that they are obliged by law to act in the manner described.12 The Court in this case did not however, describe what degree of uniformity of practice and over what duration would be sufficient for the practice to meet the requirement of constant and uniform. Nor did the Court give any indication as to the evidence that would be required before a constant and uniform practice would become a rule of customary law. 2.3.1. Opinio Juris

Most ICJ cases also require that the States who engage in the alleged customary practice do so out of a sense of legal obligation or opinio juris rather than out of comity or for political reasons. In theory, opinio juris is a serious obstacle to establishing a rule as custom because it is extremely difficult to find evidence of the reason why a State followed a particular practice. In practice, however, if a particular practice or usage is widespread, and there is no contrary State practice proven by the other side, the Court often finds the existence of a rule of customary law. It sometimes seems to assume that opinio juris was satisfied, and it sometimes fails to mention it. Therefore, it would appear that finding consistent State practice, especially among the States with the most interest in the issue, with minimal or no State practice to the contrary, is most important.

In the SS Lotus Case: France v. Turkey13, the distinction between those international rules which create a legal obligation and those which simply permit a state to act in a certain way was given. Undisputed examples of rules of customary law are (a) giving foreign diplomats criminal immunity; (b) treating foreign diplomatic premises as inviolable; (c) recognizing the right of innocent passage of foreign ships in the territorial sea; (d) recognizing the exclusive jurisdiction of the flag State on the high seas; (5) ordering military authorities to respect the territorial boundaries of neighboring States; and (6) protecting non-combatants such as civilians and sick or wounded soldiers during international armed conflict.14 The question arises as to whether opinio juris can be presumed by the general practice of states or must it be strictly proved. In the North Sea Continental Shelf Cases15, it was held that “Not only must the acts concerned amount to a settled practice, but they must also be such, or be carried out in such a way, as to be evidence of a belief that this practice is rendered obligatory by the existence of a rule of law requiring it…The states concerned must therefore feel that they are conforming to what amounts as a legal obligation…”16 2.3.2. Generality of the Practice

The recognition of a particular rule as a rule of international law by a large number of states raises the presumption that the rule is generally recognized. Such a rule will be binding on states generally and an individual state may only oppose its application by showing that it has persistently objected to the rule from the date of its first formulation.17 In the Anglo-Norwegian Fisheries Case: UK v. Norway18, the Court rejecting the argument that the ten-mile closing line for bays was a rule of customary international law, went on to observe that even if it had acquired the status of a rule of customary international law, it would be inapplicable as against Norway, in as much as she has always opposes any attempt to apply it to the Norwegian coast. Universality is not required to create a customary rule and it will be sufficient if the practice has been followed by a small number of states, provided that there is no practice conflicting with that rule. Therefore, rules of customary law can exist which are not binding on all states, as the practice may be limited to a small group of states, as was held in the Asylum Case.19 2.3.3. Relationship between Treaty and Custom

The relationship between the two flows in both directions – treaties may give rise to rules of custom and treaties may reflect pre-existing or evolving rules of custom. In the North Sea Continental Shelf Case20 the argument advanced on behalf of Denmark and Netherlands was that, even though Germany was not party to the Geneva Convention on the Continental Shelf, 1958 and was not therefore bound by Article 6 of the Convention, a rule of customary law of similar content had developed since the adoption of the Convention. The Court in this case laid down a number of conditions to be satisfied before the process of generation of a customary law from a provision in a treaty is satisfied. These are: The provision should be of a fundamentally norm-creating character. While a widespread and representative participation in the Convention would suffice, such participation must include those states whose interests would be specifically affected by the provision in question. A treaty rules would not be binding on third parties as a rule of custom if those parties have not shown their consent to the treaty. Within the period of time since the adoption of the Convention, state practice, including that of states whose interests are specifically affected, must have been both extensive and uniform.21 In the opinion of Judge Arechaga, a treaty may reflect a custom in the following ways: It may be declarative of a custom, i.e. it may codify a pre-existing rule of customary law. It may crystallize a rule of custom in the process of development. It may serve to generate a rule of custom in the future.

In the first case, the process of codification will alter the content of a customary rule. The very act of putting down in words what had before been a flexible, unwritten rule will exert influence on the content of that rule. In the second case – that of crystallization – the act of concluding the treaty may be an important example of state practice. The objective of certainty in the treaty provisions may thus be achieved at the expense of the flexibility of the rule of custom.22 2.4. General Principles of Law

General principles of law recognized by civilized nations are often cited as a third source of law. These are general principles that apply in all major legal systems. An example is the principle that persons who intentionally harm others should have to pay compensation or make reparation. General principles of law are usually used when no treaty provision or clear rule of customary law exists. Oppenheim stated that the intention is to authorise the Court to apply the general principles of municipal jurisprudence, in particular of private law, insofar as they are applicable to relations of state.23 It is difficult to establish the precise extent to which general principles have been used by international tribunals as specific reference to such sources is rarely made in their judgments. However, some references do exist. In the Chorzow Factory Case: Germany v. Poland24, it was held that the Court observes that it is a principle of international law, and even as a general concept of law, that any breach of an engagement involves an obligation to make reparation. An example of municipal principles of law being adopted by international tribunals was seen in the United Nations Administrative Tribunal Case25, where the ICJ recognized the concept of res judicata as a well established principle of law and held that the judgment rendered by a judicial body is res judicata and has binding force between the parties to the dispute. 2.5. Subsidiary means for the determination of rules of law Subsidiary means are not sources of law; instead they are subsidiary means or evidence that can be used to prove the existence of a rule of custom or a general principle of law. Article 38 lists only two subsidiary means – the teaching (writings) of the most highly qualified publicists (international law scholars) and judicial decisions of both international and national tribunals if they are ruling on issues of international law. Resolutions of the UN General Assembly or resolutions adopted at major international conferences are only recommendations and are not legally binding.26 However, in some cases, although not specifically listed in article 38, they may be subsidiary means for determining custom. If the resolution purports to declare a set of legal principles governing a particular area, if it is worded in norm creating language, and if is adopted without any negative votes, it can be evidence of rules of custom, especially if States have in practice acted in compliance with its terms. Examples of UN General Assembly Resolutions which have been treated as strong evidence of rules of customary international law include the following: • GAR 217A Universal Declaration of Human Rights (1948)

• GAR 2131 Declaration on the Inadmissibility of Intervention in the Domestic Affairs of States and the Protection of their Sovereignty (1965) (Declaration on Non-Intervention) • GAR 3314 Resolution on the Definition of Aggression.

Some of these resolutions have also been treated as subsequent agreement or practice of States on how the principles and provisions of the UN Charter should be interpreted. In addition, Article 38 fails to take into account the norm-creating effect of modern global conventions. Once the international community has spent several years drafting a major international convention, States often begin in practice to refer to that convention when a problem arises which is governed by the convention – in effect treating the rules in the Convention as customary. Examples of such conventions would be the 1959 Vienna Convention on Diplomatic Relations and the 1969 Vienna Convention on the Law of Treaties. Under Article 38(1) (d), judicial decisions are a subsidiary means for the determination of rules of law. Also, Article 59 provides that the decision of the Court has no binding force except between parties of that particular case.27 Therefore, judicial decisions are not, strictly speaking, a formal source of law. It can be argued, however, that if an international tribunal is unable to discover an existing treaty or customary rule relevant to the dispute, any rule which the tribunal adopts, will in theory at least, form a new rule of international law. An example of this was seen in the Anglo-Norwegian Fisheries case28. In the Certain German Interests in Polish Upper Silesia Case29, the Court held that the purpose of Article 59 is simply to prevent legal principles accepted by the Court in a particular case from being binding on other states or in other disputes. 2.6. Role of the International Law Commission (ILC)

The ILC was established by the UN in 1948. The 34 members of the ILC are elected by the General Assembly after being nominated by member States. They possess recognized competence and qualifications in both doctrinal and practical aspects of international law and the ILC reflects a broad spectrum of expertise and practical experience. The mandate of the ILC is the progressive development and codification of international law. The ILC usually spends many years studying areas of international law before presenting draft articles to the General Assembly for adoption as a draft convention. The primary written products of the ILC aside from the draft articles themselves are the detailed periodic reports prepared by the Special Rapporteurs on each subject and the official commentary for each draft article. Sometimes the official commentary to an ILC draft article or the Rapporteur’s report will indicate whether that draft article is intended to codify a rule of customary law or is intended to progressively develop the law on that point. When the ILC Draft Articles are approved, they are approved together with the official commentaries. The official commentaries to ILC draft articles and the reports of the ILC and its rapporteurs can be considered for two purposes. First, they are part of the travaux préparatoires when interpreting a treaty related to the subject of the draft article. Second, they are the writings of 34 highly qualified publicists speaking in unanimity and therefore serve as a subsidiary means for determining rules of customary law.30 The number of international conventions and resolutions prepared by the ILC is impressive. It has fulfilled its task of developing and codifying international law with great professionalism and dedication.


3.1. Introduction In theory there is no hierarchy among the three sources of law listed in Article 38 of the ICJ Statute. In practice, however, international lawyers usually look first to any applicable treaty rules, then to custom, and last to general principles. There are two types of norms or rules – not previously discussed – which do have a higher status. First, peremptory norms or principles of jus cogens are norms that have been accepted and recognized by the international community of States as so fundamental and so important that no derogation is permitted from them. Examples of jus cogens principles are the prohibitions against wars of aggression and genocide. A war of aggression is the use of armed force to take over another State or part of its territory. Genocide is the killing or other acts intended to destroy, in whole or in part, of a national, ethnical, racial or religious group. Second, members of the United Nations are bound by Article 103 of the United Nations Charter, which provides that in the event of a conflict between the obligations of members under the Charter – including obligations created by binding decisions of the Security Council – the Charter obligations prevail over conflicting obligations in all other international agreements. General principles are complementary to treaty law and custom. Sources that are of more recent origin are generally accepted as more authoritative and specific rules take precedence over general rules. Jus cogens (Latin: “compelling law”) rules are peremptory norms that cannot be deviated from by states; they possess a higher status than jus dispositivum (Latin: “law subject to the dispensation of the parties”), or normal international rules, and can be altered only by subsequent norms of the same status. Rules in the former category include the prohibitions against genocide, slavery, and piracy and the outlawing of aggression. Other examples of jus cogens rules are more controversial. For a jus cogens norm to be created, the principle must first be established as a rule of international law and then recognized by the international community as a peremptory rule of law from which no derogation is permitted. International law also has established a category of erga omnes (Latin: “toward all”) obligations, which apply to all states. Whereas in ordinary obligations the defaulting state bears responsibility toward particular interested states (e.g., other parties to the treaty that has been breached), in the breach of erga omnes obligations, all states have an interest and may take appropriate actions in response.

3.2. Conflict of Sources When there is a conflict between a rule of treaty and a rule of custom, the question arises as to which would prevail. While it is nevertheless accepted that Article 38 of the Statute of the International Court of Justice does not create a strict hierarchy of sources of law, it is possible to discern a number of principles and propositions relating to the hierarchy of sources: 1. General rules of interpretation apply; eg. The principle of lex posterior – a new treaty replaces an old treaty.31 And lex specialis – a special rule prevails over a general rule – will be relevant in the event of conflicting treaty provisions. 2. The North Atlantic Fisheries Arbitration: U.S. v. Great Britain32 established the principle that developments in customary law will not relieve a state of its obligations under a treaty. 3. Article 103 of the UN Charter provides that the Charter is to prevail over any inconsistent treaty obligations – a number of commentaries have suggested that this provision would apply equally to inconsistent customary law. 4. Perhaps the clearest proposition is that to be found in Articles 53 and 64 of the Vienna Convention on the Law of Treaties 1969 which provides that a treaty which is in conflict with a rule of jus cogens – peremptory rules of international law – will be void. In such circumstances therefore, rules of custom will prevail over inconsistent treaty provisions. Moreover, as stated earlier, general principles of law can only be used if there is no treaty provision and if there is a lack of customary law regarding the subject. The other sources of law mentioned in Article 38 of the Statute of the ICJ, i.e. judicial decisions and opinion of writers are subsidiary sources and are given the least significance in the hierarchy of sources. 3.3. Jus Cogens

Everything said hitherto must be regarded as subject to the rules of international law concerning jus cogens. In the event of a conflict between a rule of jus cogens and a rule of jus dispositivum, the rule of jus cogens must prevail, regardless of the sources of the conflicting rules, regardless of whether the rule of jus dispositivum came into existence before or after the rule of jus cogens, and regardless of whether the rule of jus dispositivum is more specific or less specific than the rule of jus cogens. As regards the sources of international law which can produce rules of jus cogens a wide variety of views has been expressed by writers.' Some say that such rules are derived from custom,' while others say that they can be derived either from custom or from treaties.' A few maintain that they are derived from general principles of law from either custom or general principles of law, or from either custom, treaties or general principles of law. There is one significant constraint upon terms which may be included within a treaty. Article 53 of the Vienna Convention provides that: “A treaty is void if, at the time of its conclusion, it conflicts with a peremptory norm of general international law. For the purposes of the present Convention, a peremptory norm of general international law is a norm accepted and recognised 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.”33 3.3.1. Report of the International Law Council (ILC) on Jus Cogens Judicial dicta speak of rules of jus cogens being derived from treaties or general principles of law without apparently implying that they are limited to those sources. Some authorities have argued that treaties or customs which conflict with basic principles of natural law are void; others reject this view." The travaux preparatoires of the Vienna Convention on the Law of Treaties reveal a more consistent picture. The reports of the International Law Commission said that jus cogens could be established by treaty or by custom. At the Vienna Conference, some States said that jus cogens could be derived from custom," or treaties or both. The view that treaties are one of the possible sources of jus cogens also receives support from speeches by several delegates who listed rules contained in the United Nations Charter or in other treaties as examples of jus cogens, without stating that those rules were also rules of customary law. There was little support at the Conference for the view that jus cogens could be derived from rules other than treaties and custom. The Convention defined a rule of jus cogens, not by reference to subjective notions like morality, but as a 'norm accepted and recognized by the international community of States as a whole as a norm from which no derogation is permitted'. Moreover, the consensus at the conference was apparently that rules of jus cogens could be derived only from treaties and/or custom; in other words, principles of international morality had to take the form of conventional or customary rules of international law in order to have any chance of becoming jus cogens. We have already seen that treaties and custom are normally of equal authority as sources of international law, and override other sources. It would be an anomalous departure from that general pattern if rules of jus cogens could be derived from custom but not from treaties (or vice versa), or if other sources, which are normally inferior to treaties and custom, could produce rules of jus cogens which would override treaties and custom.34 The ILC, in its endeavour to decide as to what should be considered peremptory rules, defined an international crime as an essentially wrongful act which results from the breach by a state of an obligation so essential for the protection of fundamental interests of the international community that its breach is recognized as a crime by the community as a whole.35 The rules recognized by the ICJ as being intransgerssible in character, like some rules of international humanitarian law36 and those which give rise to an obligation to the international community as a whole, like the right to self determination37 should be regarded as peremptory norms.

3.4. Soft Law Sometimes agreements which look orthodox and appear as treaties will come within ‘soft’ law definitions because they conta