Article 38 of the Statute of the International Court of Justice: A Complete Reference Point for the Sources of International Law?

By Israr Khan   Published 5 April, 2019



Sources of law determine the legal foundations of society. Like national laws, the international community has its own set of rules. However, in contrast to the nation state, the community lacks a universal legislature and a system of courts with compulsory jurisdiction; consequently this makes the task of uncovering the law somewhat difficult. Whilst article 38 of the Statute of the International Court of Justice in The Hague has been treated as a convenient catalogue of international legal sources, it actually only provides a foundation for a discussion of the relevant principles. Thus, this article will demonstate that article 38 is not a complete reference point for the sources of international law. It will first briefly shed light on the elements of article 38(1). The article will then analyse other potential sources that exist outside article 38. Since many potential sources exist outside article 38, this will only focus on jus cogens norms and unilateral declarations. It will argue whether these obligations can be categorised under the broader interpretation of article 38(1) or whether they are independent.

Elements of Article 38

Article 38 was originally adopted by the Permanent Court of International Justice (PCIJ) in 1920 and was re-enacted into the 1946 statute. Article 38(1)of the ICJ divides the sources of international law into those of a primary and secondary nature. The primary sources, which the Court will consider in its decisions, include conventions (or treaties), customary law, and general principles recognized by civilized nations.

On the other hand, judicial decisions and the teachings of highly qualified publicists are listed as merely secondary sources. Treaties are the most prominent sources of international law and are the only source available to two or more States that want to formally enter into legal relations. Customs are the general practices of States, which are accepted as law. International customary law comes into play when a specific way of behaving is, firstly, followed as a general practice among States; and, secondly, accepted by those States as legally binding. Naturally, the absence of an international ‘law maker’ has made customs a particularly important source of international law. Unless a State persistently objects, customary law binds all States. Similarly,‘general principles of law recognised by civilised nations’ are useful sources for courts to rely on when there is no suficiently articulated law available. These were inserted into article 38 as ‘gap fillers’ by drafters of the PCIJ Statute to compensate for situations where treaties and customs were insufficient to provide the legal answers.

On the other hand, judicial decisions and scholarly articles are subsidiary rules that are reflectedin article 38(1)(d). On the former, and article 59 of the Statute notwithstanding (which states that stare decisis is not part of international law), it is avered that judicial decisions actualy play an essential role in ICJ’s decisions. The ICJ has also relied upon international law commission reports. Since judicial decisions and scholarly articles are secondary obligations, judges will only turn to them in situations where they do not succeed in finding authority in one of the other sources.

Jus cogens norms: A source of Article 38(1) or external obligations?

The first external source of law applied by courts is jus cogens norms, also known as peremptory norms. Jus cogens operate as a form of public order in that they protect the legal system from incompatible laws, acts, and transactions. Some of the significant jus cogens norms include the prohibition of genocide, torture, a ban on slavery, the prohibition of aggression, the right to self-determination, a ban on piracy, and devestating cases of enviormental harm. Jus cogens hold an authoritative status as an external source outside of article 38. In fact, academics such as Alexander devotes a great deal of energy to the idea that the power of states to make treaties runs out when it confronts a superior customary norm of jus cogens. This is also affirmed by article 53 of Vienna Convention on the Law of Treaties 1969 (1155 UNTS 331) which states that: “a treaty is void if it, at the time of its conclusion…conflicts with a peremptory norm of general international law …[it is] a norm from which no derogation is permitted.” Similarly, according to article 64: “if a new peremptory norm of general international law emerges, any existing treaty which is in conflict with that norm becomes void and terminates.”Thus, the support from articles 53, 64, and the above mentioned academics clearly proves the existence of jus cogens as a complete legal authority existing outside article 38 ICJ references.

However, despite its distinctive status, some challenge the authority of jus cogens as an independent international obligation. In order to apply a law, the International Court of Justice has to refer to a source. If jus cogens are not mentioned in article 38, then where does it come from? Is the Court acting ultra vires or is it applying jus cogens as a source covered under article 38(1)? Thirlway, a scholar of international law, proposes that there is a possibility that jus cogens is a part of the customary international law of article 38(1). His reasoning is based on the argument that jus cogens results from the combination of an appropriate state practice and the psychological element of opinio juris. The ICJ seems to have articulated the same idea in the Extradite or Prosecute case in which it indicated specifically that:

“In the court's opinion, the prohibition of torture is part of the customary international law and it had become a peremptory norm” (Belgium v Senegal) 2012 ICC rep 457, [99].

This dictum suggests that the ICJ tends to categorise jus cogen as a part of article 38(1), which might make it a complete reference.

It can be argued that the above views are not absolute because they challenge the existing principles of customary law and jus cogens. Firstly, in the Extradite case, the Court did not justify the categorisation of jus cogens as customary law. Instead, it seems that the Court is accepting a parallel existence of jus cogens and customary norms. One can argue that the court is suggesting that the areas that underpin customary law may also come under jus cogens separately. Furthermore, it challenges the existing rule of the persistent objector which is only possible within the confines of the customary law. Persistent objector rule provide states with an escape hatch. Once a rule of customary international law has been established and is binding on a State ( States ), that State cannot exempt itself unilaterally from the obligations imposed by that rule. To compensate for this, persistent objector provides that if state persistently objects to a newly emerging norm of customary international law during the formation of that norm, then the objecting state is exempt from the norm once it becomes a law. The rule of peristent objector only applies to customary law. In North Sea Continental Shelf, Judge Lachs recognised the validity of the persistent obector to customary rules. However, the rule of persistent objector cannot apply to jus cogens norms because it binds states even if they object. Therefore, if jus cogensis considered a customary law, then the established law of persistent objector is null.

Additionally, if jus cogensis perceived as customary law it will also conflict with the hierarchy of international law. Currently, the consensus is that there is no hierarchy among the sources of article 38. Since article 53 of VCLT gives jus cogens an authoritative status, if considered as a customary law then jus cogens will hinder the balance of hierarchy in article 38(1). Due to the disruption of the developed principles, it is asserted that norms of jus cogens cannot be considered customary rules. Rather, these norms are a separate source of law outside of article 38.

Unilateral declarations: A treaty, a customary practice or an independent source?

Unilateral statements and declarations by state representatives can create obligations under international law. These are described as declarations of will made in public by an authority vested with the power to do so; they are unilaterally binding on the state who makes them and can be executed both orally and in writing. Unilateral declarations can be made by ahead of state, a head of government and ministers of foreign affairs, and other authorised officials.

The legal status of unilateral declarations has interesting features. Similar to a promise in the contract law of Scotland (as distinguished from an offer), it does not require any quid pro quo acceptance or reply from other states for it to be legally binding. Only if said with both an intention to bind andclear terms, unilateral declarations will have a legal effect and will be binding on the state who makes the declaration. For example, in the Eastern Greenland case (Denmark v Norway) PCIJ Series A/B No 53), the Court interpreted the declarationof a Norwegian Foreign Ministeras a statement that was legally binding onNorway. In that case, during the course of a bilateral Danish-Norwegian dialogue on the status of Eastern Greenland, the Foreign Minister of Norway, in response to Danish claims to Greenland, stated that Norway “would not make any difficulties in the settlement of this question.” When Norway later contested Danish sovereignty over the area, the Court found that earlier statement “unconditional and definitive” and therefore binding on Norway.

Although unilateral declarations are binding, the question remains whether they are a distinct source of law as opposed to that categorised under article 38. Thirlway argues that unilateral declarations can be categorised as an inchoate treaty. This claim can be supported by various arguments: a treaty is usually unilaterally ratified; states bind themselves by unilaterally ratifying a treaty; and this ratification also binds other states. In comparison, like the unilateral ratification of a treaty, unilateral acts also bind the state itself and enable other states to enforce the unilateral act. This unilateral binding was seen in the leading case of the nuclear tests when Australia and New Zealand raised an action before ICJ concerning France’s radioactive fall-out on their respective territories from French nuclear tests. The proceedings were based on the unilateral announcements of the French government. Here the Court held that:

“An undertaking of this kind, if given publicly, and with an intent to be bound, even though not made within the context of international negotiations, is binding. In these circumstances, nothing in the nature of a quid pro quo, nor any subsequent acceptance of the declaration, nor even any reply or reaction from other States, is required for the declaration to take effect, since such a requirement would be inconsistent with the strictly unilateral nature of the juridical act by which the pronouncement by the State was made.” (Nuclear test case (New Zealand v France) I.C.J. 1974 I.C.J. 457 [46])

However,despite its similarity to a treaty, it can be argued that unilateral declarations cannot be categorised as treaties under article 38(1). This is because a treaty is a binding obligation which requires efforts from both sides, whereas unilateral declarations create obligations only for one side. Furthermore, it is possible for a state to withdraw from a treaty, but a unilateral declaration that has created legal obligationson the state making the declaration cannot be revoked arbitrarily. Therefore, it is unreasonable to categorise unilateral acts as treaties.

Interestingly, it can also be asserted that unilateral declarations can be made a part of article 38(1) as a customary rule of unilateral promise. But in order to legitimise this, it is necessary to establish that unilateral declarations comply with the facets of customary law. To identify a customary rule, the elements of state practice and opinio juris need to be established. In the context of a unilateral declaration, the requirement for state practice can be satisfied but it is hard to establish the element of opinio juris. In addition, it also fails when considering the principle of the persistent objector which cannot apply because a unilateral obligation does not bind other states.

As such,unilateral declarations cannot be conventions because theyare not an agreement between two ormore states. The lines between customary law and unilateral declarations are also blurred: customary law requires state practice and opinio juris, which binds other states, whereas in a unilateral declaration the State binds itself. Therefore, article 38 is not a complete reference point for international law.


It is demonstrated in this article that article 38 is not a complete reference point for sources of international law, however it does provide the foundation for any credible discussion of the relevant principles. There are other sources of law outside article 38 that cannot be categorised as conventions, customs, and general principles. These sources include jus cogens norms and unilateral declarations. Jus cogens norms cannot be categorised under article 38 because this would disrupt the established formalities, i.e. the hierarchy of international law and the persistent objector principle. Similarly, unilateral declarations cannot be placed under article 38 because of their unilateralism.

Legal sources play a somehwhat unique role in international law; they are the argumentative tools available to the international communityand arecrucial in distinguishing between norms of a legal character and those of a ‘merely’ political, moral or ethical nature. What is clear however, beyond the decentralised nature of international law, is that legal obligations can and doemanatefrom more than one concrete source.

About the Author

Israr Khan is president of the Aberdeen Student Parliament. He is currently studying law at the University of Aberdeen.

Article picture: Wikipedia.

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