Between the various sources of International Law there exists an obvious hierarchy, in which treaty holds undisputed authority. Discuss.

The maxim lex specialis derogate generali provides no reason to automatically favour treaty over customary law. This maxim, which means that the particular or special rule will prevail over the more general one, is one of the recognised ways of resolving conflicts of law.  The use of this maxim suggests to many that treaties prevail over customary norms as they tend to be more specific in content. However, this is not necessarily the case and cannot be used to justify the undisputed authority of treaties amongst the sources of international law. Customary rules can often be specific, between a small number of states or regarding a particular subject matter. One case of note is the Asylum Case, which involved a dispute between Columbia and Peru regarding the possible granting of political asylum to the leader of an anti-government movement. The ICJ, while rejecting its existence in this particular case, expressly accepted the existence of a category of customary norms as being local or special in nature. In such a case, the existence of special (or local) custom may have the character of lex specialis over more general treaties in the same field. This situation can again be seen in the Right of Passage Case involving Portugal’s claim that a customary norm of law existed which allowed the movement of personnel through India’s sovereign territory to allow access to territory under Portuguese sovereignty. Due to the historic particulars of that region, the court found evidence that such a special custom did exist (though it did not allow for military personnel) and upheld Portugal’s claim. It is written in treaties that states remain the sole authority over a specified territory, yet in this particular case, the special custom acted as lex specialis to the treaty’s lex generali. Nevertheless, it would be folly to omit the numerous situations in which specific treaties do prevail over more general customary norms. Indeed, it seems the majority of treaties conform to this characterisation, as can be seen in the Acquisition of Polish Nationality Case and the Eastern Greenland Case. Both of these cases resulted in the application of treaty provisions in conflict with customary norms. However, this is due lex specialis derogat generali and not an automatic preference for treaties.

The other maxim commonly used in the resolution of conflicting rules of international law is lex posterior derogat priori; that the more recent rule will prevail over the earlier one. There are a number of examples which illustrate the lack of an automatic preference for treaty over custom when such a conflict arises. Customary law often necessitates the re-interpretation of an existing treaty provision. This is laid down in Article 31(3) of the Vienna Convention on the Law of Treaties. It states that at the time of interpretation, the interpreter should take into account any relevant rules of international law. Due to another principle, contemporanity, which suggests that treaty provisions should be treated as they were when the treaty was concluded, the scope for interpretation in the light of evolving customary law is “narrow and limited.” Nevertheless, it does occur, as was seen in the ICJ’s advisory opinion on the Legal Consequences for States of the Continued Presence of South Africa in Namibia. In interpreting Article 22 of the Covenant of the League of Nations, the court decided that it had to consider “the changes which have occurred in the supervening half-century” and that such interpretation must be affected the “subsequent development of…customary law.” 

In addition to the interpretation of treaty norms in light of the evolution of law, subsequent development in customary law is often used to clarify ambiguities in previous treaties. An example of such is the practice of some members of international organisations that serve to modify the organisation’s charter (a multilateral treaty). Thus, practice of the United Nations Security Counsel allows for resolutions to be passed even when some permanent members abstain from voting. This contravenes Article 27(3) of the UN Charter, which requires “concurring votes” of the permanent five. Though this may seem to be a mere technicality, it clearly shows how subsequent customary rules can develop to amend treaties. However, it must be noted that some writers consider this a matter of interpretation and not amendment. However, for the purpose of this essay, either understanding is indicative that the lex posterior maxim offers little to support the automatic preference for treaty law that such undisputed hierarchy would suggest.

3. Jus Cogens Norms and Obligations Erga Omnes

Though this essay has stressed the importance of the sovereign equality of states as the basis for the equality of the sources of law emanating from states (treaties and custom), many social developments have been underway since the 1960s that have introduced a shift towards what has been termed “international community.” This, of course, has had had legal implications. Chief among these is the acceptance of the existence of peremptory rules of international law (jus cogens) and obligations towards the whole of humanity (erga omnes obligations). Jus cogens norms cannot be derogated from and can only be amended or replaced by a subsequent rule of the same (i.e. peremptory) characteristic.

Although perhaps similar in outcome to morality-based principles found in natural law theory, jus cogens norms derive their authority from the increasingly interdependent international system alluded to above. In 1969, following the codification work of the International Law Commission, such norms were included as peremptory principles regarding the law of treaties. Article 53 of the Convention on the Law of Treaties states as follows;

        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 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.

Though expressed in terms of only “the present convention”, describing such rules as “peremptory” suggests they have universal application. The existence of jus cogens norms is supported by rulings of the ICJ and the opinions of the most respected theorists.

The ICJ, in its advisory opinion on the Legality of the Use by a State of Nuclear Weapons in an Armed Conflict decided that as such a large number of rules of humanitarian law are so fundamental to the respect for humanity, such rules are binding “on all states whether or not they have ratified conventions that contain them, because they constitute intransgressible principles of international customary law.” Though there is no direct reference to jus cogens, it would seem the description of these customary norms as “intransgressible” means that no derogation would be permitted. Such rules could therefore be described having a jus cogens character.

In the Nicaragua Case the ICJ referred to jus cogens norms in support of their decision to recognise a customary rule of international law against the use of force distinct from Article 2(4) of the UN Charter. The USA contested that, as a particular reservation to that article (The ‘Vandenberg’ Reservation) was in place, the ICJ had no jurisdiction over the matter. The court however, found that the prohibition on the use of force, as well as being in force under Article 2(4), was also in force as a customary rule of international law. Though not directly relying on Art.2(4) being in force as a jus cogens norm, the court refers to various statements made by state officials that the prohibition on the use of force is a jus cogens norm, to support “further confirmation” that it is an independent customary norm. Gordon Christenson suggests that the courts reason for supporting the customary norm independent of the treaty provision may be based on an “overriding concern for international public order” that is embodied in Art.2(4) of the UN Charter. The court’s choice does seem to imply that the prohibition on the use of force (as in Art.2(4)) is a norm of jus cogens, as the preference for the customary norm over the treaty norm (on which there was a reservation) rested on it being a “universal and fundamental principle of world order.”

The Barcelona Tractions Case, provides another reference to the importance of erga omnes obligations and jus cogens norms. Part of the court’s judgement was that states have “obligations…towards the international community as a whole” and that such obligations “derive, for example…from the outlawing of acts of aggression, and of genocide” among others. Another example of erga omnes obligations is to be found in the ICJ’s ruling of 1996 with regard to Convention on the Prevention and Punishment of the Crime of Genocide, determined that “the rights and obligations enshrined by the convention are rights and obligations erga omnes.”

Jus cogens norms thus constitute a crucial part of international law. However, to determine its relation to conventional and customary law, it is now necessary to discuss how jus cogens norms can be formed.

Jus cogens norms can emanate from either conventional law, customary law, or both. Ian Brownlie suggests that this is not the case and that customary law is the basis of jus cogens. However, the majority view suggests that both treaty and custom can provide such norms. This seems to be the more logical approach as treaty and custom tend to be of equal value and superior to the “general principles of law” and it would be anomalous if general principles could provide rules to override those derived from sources superior to them. This is also supported by the positivist doctrine that treats conventional and customary law as equal expressions of the will of states, upon which international law is based. It is this derivation that separates jus cogens norms from morality principles based on natural law theory. As treaty and custom are both expressions of the will of states, jus cogens norms remain applicable in a positivist sense. This is also apparent in Art.53 of the Convention on the Law of Treaties, which states that in order have a jus cogens character, a norm must be “accepted and recognised by the international community of states as a whole.” It is this strict positivist basis, however, that leads to many of the difficulties associated with jus cogens, to which this essay shall now turn.

The provision of Art.53, that in order to have jus cogens character, norms must be accepted as such by the “international community of states as a whole”, severely limits the number of rules that would qualify. It is disputed whether this provision means full unanimity or simply an overwhelming majority of states. Akehurst suggests a compromise; the rule must be accepted by all states as law, and accepted by the overwhelming majority as jus cogens. Very few norms would pass this test however. The prohibition on the use of ‘aggressive’ force as provided by Art.2(4) of the UN Charter would be considered one of the few that do. As all states are parties to the Charter and the majority accept this provision as a jus cogens norm. Alfred Verdross has consistently argued that all humanitarian laws are jus cogens norms. However, it is unclear what norms of a ‘humanitarian’ nature would qualify as jus cogens norms. The Universal Declaration of Human Rights, adopted by the UN in 1948, includes such rights as the right to belong to a trade union, yet it is doubtful whether this provision would have a jus cogens character. In recent years, the prohibition on torture has become increasingly accepted as a jus cogens norm. The ICTY found in 1998 that “torture is prohibited by a peremptory norm of international law.” Also definitely included as jus cogens norms are the prohibitions on slavery, piracy, as well as genocide, as was seen in the Reservations to the Genocide Convention. The ICJ proclaimed in the East Timor Case that the right of peoples to self determination “has an erga omnes character.” However, it is easy to see how these norms rely on much interpretation and thus a clearer definition of jus cogens norms remains difficult. Though there is substantial agreement on the existence of the jus cogens category of norms, the content of this category remains a matter of huge debate.

The existence of jus cogens norms, even though there may be confusion as to what norms have this status, act as a limit on states regarding their freedom to conclude treaties. If treaties are limited in this way and subject to acting in accordance with jus cogens, then they cannot be said to hold “undisputed authority.” In fact, it is the jus cogens category that tops the hierarchy.

4. The General Principles of Law

Article 38(1)(c)  refers to “general principles of law recognised by civilised nations.” Though generally considered to be subsidiary to treaty and customary law, this clause can impact on the formulation of treaties and customary rules and certainly questions the existence of an obvious hierarchy.

Some writers, particularly those of what was known as the Soviet school, such as Tunkin, argue that this provision does not refer to sources of international law at all, but to “non-normative” methods for determining law, referring to those maxims discussed above. Similar views are found in the writing of Kelsen who finds that they are superfluous as they can only be part of international law if they are found in treaties or custom. However, this view is a minority. The view that the provision does indicate a genuine source of international law is split into two camps; one asserts that it refers to general principles of municipal law that may be applicable to the international sphere; the other that it refers to general principles of international law distinct from customary law. Of the former view are Oppenheim, Lauterpacht, Favre, and many others. According to Favre, “the general principles of law are…norms underlying national legal orders.” This view finds some support in some case-law, whereby national law common to both parties, or to states generally, has been applied to an international situation.  In the case of AMCO v. Republic of Indonesia, the international tribunal stated that the awarding of full compensation to the injured party is “a principle common to the main systems of municipal law and…may be considered a source of international law.”

Art.31 (1)(c) can also be construed as meaning general principles of international law. As noted by Lammers, from a textual point of view “principles of law” may refer either to municipal or international law and “recognised by civilised nations” may be viewed as internal recognition (municipal) or external recognition (international). In this international sense, general principles are often identified with customary law. However, the general principles of international law, though induced through customary norms (and through treaties), reflect a broader application of such principles, as opposed to the more specific rules of customary rule. In this sense, these principles are related to customary rules in that they find expression through state practice and are supported by the belief that they are law (opinio juris). However, whereas customary rules refer to specific practice (which as has been seen may be more specific than treaties), general principles are the common principles underlying customary rules. The same derivation can come through common provisions of treaties. Perhaps the best perception is that Art. 38(1)(c) is seen as referring to both general principles of municipal law and general principles of international law. There seems to be no reason why the two concepts are mutually exclusive.

The general principles of law are commonly regarded as being subsidiary to treaty and custom. Their inclusion in the Statute of the ICJ is considered to be for the purpose of avoiding a non liquiet situation. However, it can be argued that general principles have a more substantial role.

General principles of law can have an interpretive effect on treaty-based law. General principles of municipal law common to many states (possibly only two, if it is those two states involved in a dispute) may be used by an international court to interpret vague or uncertain provisions contained in a treaty or in customary rules. This can be seen regarding the common rules legally separating companies from shareholders, found by the ICJ in the Barcelona Traction Case to be “rules generally accepted by municipal legal systems.” With regards to general principles of international law, they too may serve in an interpretive manner. Article 31(3)(c) of the Vienna Convention on the Law of Treaties provides that “any relevant rules of international law applicable in the relations between parties” Shall be considered when interpreting treaties.

General principles can also have a persuasive effect on treaty-based law. Though in this sense they do not amount to a normative source, the influence they may have on the framing of a treaty certainly provides reason to doubt any “undisputed” authority the latter may have and, even more so, serves to blur any hierarchy. It has been seen that Art 38(1)(c) may provide for either general principles of municipal law or general principles of international law. It is widely accepted that these are subsidiary to treaty and customary law. Nevertheless, the interpretive effect that they can exert over treaties (or custom) does serve to dispute the proposition that this essay has sought to disprove.

5. The Framing of the Statute

In this section, it shall be shown how the framers of the Statute of the ICJ rejected the idea that provision should be made to indicate a hierarchical structure in Article 38(1). When drafting the original text for Article 38 of the Permanent Court of Justice, the Advisory Committee of Jurists considered a proposal to include a statement listing the order of application of the sources of international law in the “undermentioned order.” M. Ricci-Busatti opposed this proposal on the grounds that it was not the committee’s intention to have judges automatically apply points (a) and (b) (treaty and custom) before applying point (c) (general principles). Considering this, Baron Deschamps argued that there existed a “natural classification” that treaties, if relevant, would apply before custom, and custom before general principles. However, with support from other members of the committee, Ricci-Busatti concluded that the proposal was superfluous. The maxim of lex specialis derogat priori ensures the most specific rule is applied, and various sources “may be applied simultaneously. This essay has already shown how the lex specialis maxim can apply as much to customary norms as it does to treaties. Considering the arguments of the committee strengthens the contention of this essay that custom and treaty hold equal authority beneath rules of jus cogens.

Conclusion

It has been argued throughout this essay that any contention asserting the supremacy of treaties as a source of international law is misleading. Instead, it has been argued that jus cogens norms are of paramount authority. Beneath these norms, it has been seen that conventional and customary law hold equal weight and that general principles of law can exert influence on both of these. In Section 1, the statute of the ICJ was examined. It was seen how the main sources of international law are given here, and that it constitutes a viable source for the discussion of those sources. In section 2, a discussion of the relationship between treaty and customary norms illustrated how the two hold equal authority. Through looking at cases dealt with through the ICJ and at the writings of major jurists, it was seen that two maxims apply to prioritising sources of law. Neither of these maxims offers any preference to treaty over custom, as both lex specialis and lex posterior treat each source equally. Section 3 dealt with the relatively recent development of jus cogens norms. It was seen that its development through the Convention on the Law of Treaties has led to general acceptance of this category of legal norm. Through analysis of ICJ judgements, particularly regarding the Barcelona Traction Case and the Nicaragua Case, it was seen that these norms cannot be derogated from, through either treaty or customary rules, though it was also seen that it is through these norms that jus cogens norms come about.  Nevertheless, as has been seen, there are many problems of interpretation regarding jus cogens norms and thus the actual norms that constitute this category are difficult to clarify. In the penultimate section of this essay, the ‘general principles of law’ were examined. It was seen that these may be in the form of general principles of municipal law or of international law. This essay found that, although these principles only usually apply in the case of non liquiet, they can also have an interpretive and influential effect on treaty law. Thus the hierarchy described above becomes blurred. In the final section, this essay briefly examined the historical basis of the drafting of the ICJ statute. It was seen, that attempts to create a hierarchy were consciously avoided by the drafters, adding further confirmation to the general contention of this essay.  Treaties do not hold undisputed authority in an obvious hierarchy amongst the sources of international law. They constitute, along with customary law, a source that is always subject to the higher principles of jus cogens. In addition, the hierarchy itself is vague rather than obvious, with general principles confusing the matter.

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