Panel 3.2 / Actor Variety in the Content-Determination of CIL
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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.
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.
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.
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.
TRICI-Law - The Rules of Interpretation of Customary International Law 