Panel 3.2 / Actor Variety in the Content-Determination of CIL

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3.2.1 / Catherine Brölmann
Is the Classical Paradigm of State Practice and Opinio Juris Still Valid Today?

The two-element doctrine regarding the formation of customary international law has been a longtime subject of (inconclusive) debate, involving philosophical, theoretical, doctrinal and heuristic perspectives (with due regard for the variety of meanings given to these terms in the context of law). One well-known facet has been the interplay and weighing of the two elements (as e.g. in the distinctions between ‘wise custom and wild custom’ (Dupuy 1974) and between ‘traditional and modern custom’ (Roberts 2001)); another is the question of whether to speak of two separate elements (in the context of law ascertainment often put as ‘requirements’) is even justified. That said, the title proposed by the organizers refers to a ‘classical’ paradigm, and indeed it seems that as a doctrine the two-element approach is invariably in use.

The present paper responds to the diachronic aspect of the title, and addresses the question whether the two-element doctrine will be tenable, or continually ‘valid’, in twenty-first century international law. The point made in the paper is that the conceptualization of the two-element doctrine has been closely connected to the sovereign state, more than to the ‘international legal person’ in abstracto. While this is not surprising, given the fact that states for a long time were considered to be the sole international legal persons, it has brought specific political and philosophical connotations to the thinking about custom formation.

Thus, the power of ‘practice’ as a component of customary international law is in part linked to the absolute authority of the sovereign state in its own sphere, with factual conduct counting as an expression of sovereign Will. Opinio juris refers to a legally relevant ‘state of mind’, which – even if the anthropomorphic view of the State and its legal ‘personality’, was to some extent dismantled by Interbellum scholars and has been the object of contestation ever since international law has remained discretely at ease with projecting onto States.

To examine whether the two-element doctrine is future-proof, we must look at trends in international law today. The two most prominent ones are the increase in shades of normativity and the arrival of new actors. Since custom as such is a formal source, the relevant test of validity is whether the two-element paradigm can perform its function in relation to a non-state actor. The candidate then is the international organization: of all non-state actors the most fully-fledged participant in international legal affairs. Proceeding from there we find that international law is hesitant when it comes to the identification of practice as a separate expression of international organizations and the attribution of opinio juris as a belief held by organizations in the way of states. This has been recently confirmed by the modest role of international organizations as independent actors in the 2018 ILC Conclusions on identification of customary international law.

With the arrival of non-state actors the two-element doctrine from a theoretical perspective remains problematic as ever – and the construal of practice as evidence of opinio juris arguably the most convincing. The conclusion of this paper is that, however, as a heuristic device the two-element doctrine is needed even more than before, because for their lack of ‘sovereign power’ non-state actors such as IOs are less readily seen to generate custom based either only on practice or only on opinio juris.

3.2.2 / Machiko Kanetake
Critical Analysis of the Formation of Customary International Security Law

In the development of customary international law, ‘silence’ can be an indication of states’ acceptance. According to Conclusion 10.3 of the ILC 2018 draft conclusions, ‘[f]ailure to react over time to a practice’ ‘may serve as evidence of acceptance as law (opinio juris)’. While this conclusion reflects the reality of international relations where states choose not to react to other states’ practices for strategic reasons, the lack of explicit reaction can be the result of many political and pragmatic obstacles that constrain states’ conduct. To overlook considerable variance among states would mean to maintain the exclusion, from the process of developing customary international law, of those politically marginalised states whose interests may eventually be affected.

Against this background, this paper aims at situating states’ ‘silence’ in the context of the development of jus ad bellum. The focus of the paper is directed at the permissibility of the use of force in self-defence against non-state attacks. The topic has been extensively debated during the last two decades, and, given the maturity of academic discussion, the paper by no means intends to answer the question of whether such use of force is legally permissible. Instead, this paper highlights both doctrinal and pragmatic factors that exclude certain actors and perspectives from the deliberation of customary international law concerning the use of force in self-defence.

If one consults academic literature published within several years after the September 11 attacks, it is readily possible to present a plausible argument that self-defence against non-state attacks is legally permissible where the territorial state is unwilling or unable to prevent further attacks. While the initial literature has been subject to critique, the question remains as to why controversies regarding self-defence against non-state attacks, as well as the related ‘unwilling or unable’ doctrine, did not occupy a good deal of attention from the outset in academic discussions in leading journals published in English, as well as in practice. This is not only because of a crisis mind-set which often leads the development of customary international law, but this is also due to the doctrines of customary international law, which preserve and endorse the existing political power asymmetry. The idea that the passage of only a short period of time should suffice works in favour of those states and organisations which have better accessibility to relevant information. The same holds true for the doctrine of specially affected states. This is accompanied by the fact that many states are effectively prevented from being in a position to react to other states’ practices. This paper also refers to the problem embedded in the publication of academic journal articles. Due to their quest for originality, the articles which confirm the status quo in the interpretation of self-defence tend to be much less visible than those articles which highlight possible changes in the scope of self-defence.

3.2.3 / Maiko Meguro
Behind the Fiction of Opinio Juris: The Actors that Actually Create International Law

This presentation challenges the concept of opinio juris which is widely understood as an “unintentional” form of legal ascertainment in contrast to consent – an intentional from of legal ascertainment in treaty making. Opinio juris is usually construed as a belief that the legal obligation “had existed” at the time of State conducts. This position presupposes that the State came to accept a legal obligation at an intangible time in the past, and neither the State nor the Court can identify when and how a certain practice is ascertained as being a legal obligation or a right to act. In case of customary international law, legal ascertainment is construed as a gradual process without a demonstrable threshold. This approach remains dominant in the latest International Law Commission (the ILC) Conclusions on identification of customary international law.

This contribution raises the question of the (im)possibility for a State to be bound by a legal obligation unintentionally without a moment of formal acceptance. In grappling with this question, this contribution seriously revisits the idea of opinio juris as the belief that the legal obligation “had existed” at the time of State conduct. It shows that such an idea is built upon a fiction of anthropomorphism of State will, and further demonstrates that this fiction is a fallacy in customary law making when it is looked at through the lens of domestic decision-making process. Once is has shed light on this fallacy, this contribution shows that various actors contribute to the production of a “State will”. Whilst this plurality of actors behind the veil of State is somehow recognized in the context of state practice as understood by the ILC, it has been completely overlooked with respect to the creation of opinio juris.

The presentation seeks suspend the fiction created by anthropomorphism and elucidate how States actually create acceptance of law. It thus focusses on the process behind the veil of State to create a State position which is perceived as a State will (e.g. opinion juris, acceptance as law or even a consent). The main claim is thus that a state position is the outcome of internal decision-making process participated by domestic actors with varied motivation and interests.

It is submitted that the implications of this claim are wide-ranging for current legal scholarship on the sources of international law. With respect to opinio juris, this raises a serious question about the idea of opinio juris as an unintentional form of legal ascertainment. The fiction incorporated to the concept of “State will” cannot function (and make sense) for opinio juris (or acceptance as law), as an intentional form of legal ascertainment is not possible under the internal decision-making process. This internal process can only accommodate conscious decisions by a State. In the light of this decision-making process, no State can possibly accept any obligation without knowing when and how.

3.2.4 / Zhuo Liang
The Practice of Non-state Armed Groups and the Formation of Customary International Humanitarian Law: Towards a Direct Relevance?

Under the classical approach, customary international law (CIL) can only be derived from state practice and opinio juris. However, this two-element doctrine of CIL has been under challenge from an undeniable phenomenon that various non-state actors have been playing a part in contemporary international law-making. International humanitarian law (IHL), on its part, confronting the frequent occurrence of non-international armed conflicts since World War II, has substantially involved the behaviors of non-state armed groups (NSAGs). This background leads to the question how we should evaluate the practice of NSAGs in the context of formation of customary IHL, e.g. to absorb it into state practice, to accept it as another independent avenue of the formation of customary IHL, or to negate its values anyway.

The ICRC customary IHL study collected practice of NASGs, but listed it under the heading of “other practice”, which was invoked to reflect rather than determine the existence of customary IHL norms. On the other hand, a prominent example of authoritative recognition of the relevance of practice of NSAGs to formation of customary IHL can be found in the Tadić case, in which the ICTY Appeals Chamber considered the unilateral declarations by both conflicting parties, including NSAGs, could contribute directly to the formation of customary IHL. Scholars have discrepant opinions on whether and to what extent the practice of NSAGs should be recognized as a constitutive element of customary IHL. Such a discrepancy of views reveals the lack of clarity of the status of NSAGs’ practice in the formation of customary IHL.

This article holds a positive view on the relevance of NSAGs’ practice to the formation of customary IHL. Not confined to this traditional yes-or-no question, it moves further and spends its length on elaborating on the possible approaches and consequences of incorporating NSAGs’ practice into the formation of customary IHL. Part I of this article will expound why there are good reasons to affirm the relevance of NSAGs’ practice to the formation of customary IHL in general. Part II will examine different angles of such incorporation. A series of questions are to be discussed: Which types of practice and armed groups are relevant to the formation of customary IHL and which ones are not? Should NASGs’ practice be seen as part of state practice or an independent element of customary IHL? Assuming it is an independent element, should it be weighed as equal or infer to state practice in terms of its significance for formation of customary IHL? Part III will deal with the legal consequences of potential existence of multiple customary IHL norms, as a result of recognizing NSAGs’ practice as an independent element of customary IHL. Such norms may include those formed through pure state practice, through co-practice of state and NSAGs and through pure NSAGs’ practice. What are their respective scopes of application and how can we handle its undermining of the uniformity of customary IHL? Conclusive remarks will be made in the end based on the previous findings.