Lies behind the “Reference Definition” of Customary International Law (CIL)?


By Fabián Augusto Cárdenas Castañeda

PhD (cand.) in International Law from Pontificia Universidad Javeriana

Founding member of Colombian Academy of International Law 

Taking advantage of the opportunity to write an scheduled contribution in the Blog of the Colombian Academy of International Law, Debate Global, I decided to share some of the theoretical concerns that lie behind my current research on the sources of international law and more particularly on “the” theory of customary international (CIL), which I believe is based on lies and impossibilities. I believe CIL is rather an argumentative framework.

When I first attended an introductory course on international law I was taught that customary international law was what the ICJ Statute says it was. Article 38 of the ICJ Statute declares: “[…] international custom, as evidence of a general practice accepted as law”. Accordingly, I was also taught (as some of you may have) that CIL was formed by two ingredients, namely: state practice and opinio juris; the former the objective element and the latter the subjective element. Once the two of them were present, there we go! Customary international law it is.

Initially, and as part of my own learning process, I assumed that the Statute definition was more like a “recipe” for CIL, as it tells you which are the required two “ingredients” in order to have this unwritten source of international law. It sounded very simple then but I have come to realize that it was just a euphemism. That is also why I have been sarcastically using this cooking analogy in my current research; in fact, the last article I made with the insightful academic contribution of my brilliant student Oscar Casallas, is titled: A Large Cup of Opinio Juris and State Practice to Taste: The Recipe of Contemporary Customary International Law?. There I challenge the two ingredients recipe of the ICJ (reference) definition as to discuss whether opinio juris may be the only required ingredient of today’s CIL.

Despite of having this apparent useful but misleading CIL reference definition, as I continued my studies I started to question what I though it was the true about CIL and the sources of international law. Was not the ICJ Statute suppose to regulate only its own functioning? Why do we use the ICJ Statute as if it were the universal secondary rule governing the sources of international law? And even more confusing, was article 38 definition of CIL a customary rule in itself? How did it become CIL, by what it says CIL is?

Behind this there were even more complex questions assuming that article 38’s definition was the right one. Why only state practice if I have been also taught that there are more subjects of international law besides states? What do we mean by “state practice”, the practice of all states, few states, powerful states? How do we find the opinion that some practice is rendered obligatory by international law? Should it be expressly manifested by states? Should we equate what states say with what they actually think or belief in order to identify opinio juris? Do states think or believe by themselves? And, off course, this kind of questions did not come exclusively by my individual insight, rather they were boosted by loads of contemporary international literature that discusses the theoretical and practical accuracy of what I call “the Reference Definition” of CIL, since it is the one it is referred to whenever it is asked about what CIL is.

The abovementioned concerns brought me to agree on the need to reconsider the sources of international law. That’s precisely what led me to write “A Call for Rethinking the Sources of International Law: Soft Law and the other side of the Coin”, where I supported the idea that the sources of international law were not exclusively the ones listed by the ICJ Statute and that even the ones listed may not be what they originally were when the norms were drafted.

As regards the abovementioned “Reference Definition” of CIL, and even if we hypothetically assume that this was the right concept, I can nothing but agree with Curtis Bradley that it certainly has evidentiary, practical and conceptual difficulties.

The most mentioned conceptual problem (surely not the only one!) is that such definition suffers from “putting the cart before the horse”, just as H. Waldock illustratively describes it. This means that that CIL is not the evidence of a general practice accepted as law but the other way around: general practice accepted as law is (may be) the evidence of CIL.

One discussed evidentiary difficulty is that there is not agreement on how to prove the existence of CIL’s ingredients. Some say that it is through actual practice, others that diplomatic practice is what should prevail, and sometimes even the very ICJ ends up equating both elements when it comes to demonstrate their presence in a given situation. For instance, it is well know the radical different approach of the North Sea Continental Shelf Cases on the one hand and the Nicaragua Case on the other. Whereas in the former the ICJ went through the analysis and presentation of a decent amount of practice, in the latter the decision was taken more on light of different sorts of international law paper work.

Likewise, the most evident practical difficulty of the “Reference Definition” is the so-called “Chronological Paradox” which consists in the actual impossibility to create or modify CIL. If CIL comes from practice performed out of a sense of a legal obligation, how can CIL be initiated? If a state “A” is behaving in a way convinced that it is acting because such behaviour was legally required, then there may be two possibilities: either such CIL already existed (and this was not the beginning of the customary rule) or state “A” was not acting in accordance to international law; its behaviour could be praeter legem (outside the law) or contra legem (against the law). The point here is that whereas article 38’s reference definition may make sense for already functioning CIL, it does not work for new CIL because the initial stage cannot exist within such concept due to the lack of actual opinio juris or the presence of a violation of international law in the very first place.

Furthermore, if we study the jurisprudence of the ICJ we can find out that not even the Court itself applies the recipe it says it follows. On this regard the 2014 Keynote Speech of Professor James Crawford before the ILA titled “The Identification and Development of Customary International Law” (video) is absolutely discerning.

In his intervention, Professor Crawford unveils the unsystematic approach of the ICJ with regards to identifying customary international law. Whereas sometimes the Court does not even require much opinio juris or even practice, sometimes it solves an issue by solely affirming that a particular norm is or is not customary international law. “In the Nicaragua v. Colombia case, the Court just asserted that the definition of the continental shelf set out in Article 76(1) of UNCLOS, the legal regime of islands set out in Article 121, and the 12-mile territorial sea set out in Article 3, reflected customary international law. In the Qatar v. Bahrain case, the Court held that Article 13 of UNCLOS on low-tide elevations reflected customary international law, a dictum later taken up in Nicaragua v. Colombia” (Crawford). I also agree “Customary international law is that source of international law that most aptly encapsulates the changing practice and attitudes of states”. However I do not believe there is even a formal rule to both ascertain and evidence CIL, as there is rather argumentative artillery to be used by international lawyers.

Nonetheless, this foregoing situation of theoretical indeterminacy and hypocrisy of CIL’s Reference Definition is what has motivated Professor d’Aspremont to describe “CIL as a Dance Floor”, an intellectual prison “where (almost) every step and movement is allowed or, at least, tolerated”.

Although I do not aim to solve the whole CIL situation in an informal contribution made through legal blogging, it is my purpose to foster awareness of the need to stop sweeping under the carpet. We, international lawyers, should stop using this “Reference Definition” of CIL as if things were all right with it, because they aren’t.

Notwithstanding, it does not mean that CIL is not a fundamental international legal source anymore, because –on my view- it continues to be a foundation of international law. On this regard I think that Baron Descamps’ description of CIL continues to be accurate: “ [CIL is] a very natural and extremely reliable method of development [of international law] since it results entirely from the constant expression of the legal convictions and of the needs of nations in their mutual intercourse”.

I believe that CIL should continue to be at the centre of the international legal research, however it should be demystified. I guess that the recent (2012) inclusion of the topic “Identification of Customary International law” within the work of the UN International Law Commission corroborates the importance of the matter. It is just unfortunate that the initial reports of the Special Rapporteur, Sir Michael Wood, have proved to have an orthodox approach of CIL, mainly attached to the traditional considerations and difficulties of the Reference Definition. I just hope this is just because the initial reports aimed to codify the state of art in order to further develop the understanding of CIL by unmasking the inadequacies of article 38’s definition and its consequent theorization.

I believe that the ILC and those working on the field of the sources of international law should expose the lies hidden behind the classic definition of the ICJ Statute so a contemporary theory of CIL can emerge transparently; a consistent theory should say, describe and explain what CIL really is (or what it is wanted to be?) and not what an obsolete and decontextualized written text says it is. However, it is the aim of my on-going research -which I recently presented at Universidad Javeriana (video)-, to demonstrate that none of the existing theories of CIL is accurate enough because “the” theory cannot be found. Theorists will not find the perfect secondary rule governing CIL probably because there is not such rule and the operation of CIL cannot be equated to e.g. the law of the treaties. On the contrary, I really think that what we have instead is a set of finite available arguments to be used by the community of international lawyers who practice and research on CIL; those arguments are not completely undetermined but are formed by the variety of alternative theories trying to explain CIL. Is then CIL rather an argumentative framework?



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