1 Introduction
Customary international law (CIL), as it is commonly construed in international legal thought and practice, is grounded in a particular social reality. In fact, the two constitutive elements of CIL, namely practice and opinio juris, correspond to two sides of the social reality which CIL is supposed to be grounded in. This is no new state of affairs. Even in the nineteenth century where CIL was thought to be the product of tacit consent, customary international law was construed as the product of social reality.Footnote 1 This social grounding of CIL is certainly neither spectacular nor unheard of. That CIL is grounded in a particular social reality bespeaks a construction that has become rather mundane since the Enlightenment,Footnote 2 and according to which norms are no longer supposed to be received by their contemplatingFootnote 3 addressees but are collectively producedFootnote 4 by them as members of a self-conscious social community.Footnote 5 Such an understanding of the making of CIL as originating in a process of self-production, where the authors and the addressees of the customary norm are conflated,Footnote 6 is a manifestation of modern thinking.
Although simple in principle, the grounding of a norm in a social reality is a construction that commonly calls for a number of discursive performances for this grounding to be upheld in the discourse.Footnote 7 The present chapter zeroes in on one of these discursive performances that is required for CIL to be grounded in social reality, namely the postulation of a moment in the past where the social reality actually engendered the norm. In fact, the grounding of CIL in a social reality captured through practice and opinio juris can only be upheld if there was a moment in the past where the practice and opinio juris of states – and possibly of other actorsFootnote 8 – have coalesced in a way that generates customary international law. In other words, for CIL to be grounded in social reality, there must have been a moment in the past where customary international law was actually made.
This chapter argues that, in international legal practice and literature, the actual moment where social reality has engendered a customary norm is never established or traced, but is always presupposed.Footnote 9 According to the argument developed here, the moment CIL is made is located neither in time nor in space. Customary international law is always presupposed to have been made through actors’ behaviours at some given point in the past and in a given place. Yet, neither the moment nor the place of such behaviours can be found or traced. In other words, there is never any concrete moment where all practices and opinio juris coalesce into the formation of a rule and which could ever be ‘discovered’. This means that the behaviours actually generating the customary rule at stake are out of time and out of space. Because the custom-making moment is out of time and out of space, it cannot be located, found, or traced, and it must, as a result, be presumed. This is why current debates on CIL in both practice and literature always unfold as if all actors’ behaviours and beliefs had at some point coalesced into a fusional process leading to the creation of customary international law. However no trace of that fusional moment can ever be found, condemning this original fusion of all behaviours and beliefs to be presumed.Footnote 10 This presumption of a moment in the past where the social reality creates the norm is called here the presumption of a custom-making moment. Most debates on CIL in practice and in the literature are built on such a presumption of a custom-making moment. As was said, this presumption of a custom-making moment is necessary for CIL to present itself as being grounded in a certain social reality.
This chapter is structured as follows. It first sketches out some of the main manifestations of this presumption of a custom-making moment (1). It then sheds light on some of the discursive consequences of presuming a custom-making moment, including those consequences for the interpretation of CIL (2). The chapter ends with a few observations on what the presumption of a custom-making moment entails for foundational debates about CIL as a whole (3).
Before elucidating the manifestations of the presumption of a custom-making moment and its consequences, a preliminary observation is warranted in light of the presumptive character of the custom-making moment. It could be claimed that the presumption of a custom-making moment is, like opinio juris,Footnote 11 yet another fiction around which CIL is articulated. In that sense, the custom-making moment would be a fiction about the origin of CIL. It is submitted here that claiming that the custom-making moment is a fiction says basically nothing about what such a presumption stands for and actually does. Indeed, it could be said that international law’s representations of both the reality and the past are always fictitious constructions.Footnote 12 What is more, fictions have always been a common mode of representing the real.Footnote 13 That CIL rests on a fictitious representation of the moment of its making can thus not be demoted to just another fiction of international legal reasoning. It is a powerful discursive performance without which CIL could not do all what it does.
2 The Custom-Making Moment in the International Legal Discourse
The following paragraphs mention a few of the manifestations of the presumption of a custom-making moment in international legal thought and practice. It is, for instance, noteworthy that practice and scholarship continuously set aside the question of the duration of practice, as the determination of a minimum threshold would bring back the question of the custom-making moment.Footnote 14 The recurrence of the metaphoric shorthand of ‘crystallisation’ to describe the formation of customary law in the literature similarly epitomizes the continuous avoidance of finding a custom-making moment and the presumption of the latter.Footnote 15 In the same vein, it is striking that courts always locate the practice and opinio juris they find in the present,Footnote 16 thereby constantly avoiding the tracing of a custom-making moment.
The presumption of a custom-making moment has occasionally been touched on in the literature. For instance, the famous discussion on the chronological paradox of CIL is a question that, although focused only on opinio juris, is all about the abovementioned presumption of a custom-making moment.Footnote 17 Yet, those debates on the chronological paradox of CIL never explicitly acknowledge the presumption of a custom-making moment. Reference could also be made to scholarly discussions about the relations between a customary international legal rule with a corresponding existing treaty provision.Footnote 18 In this situation, the treaty seems to provide some indication of the time and place of the making of CIL.Footnote 19 And yet, here too, despite the treaty providing some vague direction in this regard, there is no effort to identify a custom-making moment, the latter remaining presumed.
It is remarkable that the International Law Commission (ILC), in its work on the identification of CIL, consciously decided not to look into the custom-making moment either. Indeed, as it stated in the commentaries to its 2018 conclusions:
Dealing as they do with the identification of rules of customary international law, the draft conclusions do not address, directly, the processes by which customary international law develops over time. Yet in practice identification cannot always be considered in isolation from formation; the identification of the existence and content of a rule of customary international law may well involve consideration of the processes by which it has developed. The draft conclusions thus inevitably refer in places to the formation of rules of customary international law. They do not, however, deal systematically with how such rules emerge, change, or terminate.Footnote 20
Interestingly, it is this very choice to exclude the question of the formation of customary law from the scope of its work that entailed a change in the way in which the ILC described its own work.Footnote 21 It is submitted here that such a choice is not informed by the material impossibility to trace the formation of CIL or the irrelevance of the question for custom-identification, but by the very fact that this presumption is at the heart of the contemporary understanding of CIL. Being presumed, it does not even need to be traced. In the discourse on CIL, the question of establishing or tracing the custom-making moment simply never arises.
3 The Custom-Making Moment and its Doings
It is argued here that the presumption of a custom-making moment is not just a move of convenience to evade difficult methodological and evidentiary obstacles pertaining to the identification of CIL. Such a construction is being perpetuated for its many discursive virtues. Indeed, as was indicated above, CIL could not be upheld as being grounded in social reality if it could not be presumed as being made at a certain moment in the past. If it were not presumed to be made at a given moment in the past where opinio juris and practice coalesce and generate CIL, it would not be possible to hold that CIL originates in some form of social reality.
In enabling the grounding of CIL in social reality, the presumption of a custom-making moment simultaneously allows some other discursive moves which are worthy of mention here. In particular, attention must be turned to the way in which the presumption of a custom-making moment enables a two-dimensional temporality in the discourse on CIL. In fact, it organizes the life of CIL around two distinct moments, namely: (i) the (presumed) moment of making of CIL in the past; and (ii) the application of CIL in the present.Footnote 22 If CIL has a past, albeit presumed, it can have a present distinct from that past. The postulation of a custom-making moment in the past thus allows the postulation of other ‘moments’. In particular, this two-dimensional temporality enables the idea that CIL is a product made in the past and subjected to interpretation in the present. Because one presupposes a custom-making moment in the past, one can think of CIL as a tangible artefact in the present which can therefore be subject to an autonomous and neatly organised interpretive process.Footnote 23 This is why those scholars that argue that the interpretation of the content of CIL can be distinguished from the interpretation of its legal existenceFootnote 24 extensively and systematically build on this two-dimensional temporality.Footnote 25 In that sense, the current scholarly attempts to distinguish the interpretation of the making of the CIL rule from the interpretation of its content can be seen as being predicated on this presumption of a custom-making moment.
There is another important consequence of the presumption of a custom-making moment that ought to be mentioned here. That is, the anonymity and impunity in argumentation about CIL that accompany the presumed custom-making moment and its abovementioned two-dimensional temporality. Indeed, since the custom-making moment is outside time and out of space, and simply presumed, those generating the custom-making behaviours cannot be known. The only possible pedigree of customary international law comes to be reduced to ‘all states at some point in the past’. Being presumed, the custom-making process is actually anonymised. This anonymity is explicitly confirmed by the ILC:
The necessary number and distribution of States taking part in the relevant practice (like the number of instances of practice) cannot be identified in the abstract. It is clear, however, that universal participation is not required: it is not necessary to show that all States have participated in the practice in question. The participating States should include those that had an opportunity or possibility of applying the alleged rule.Footnote 26
The above statement shows that it is not necessary for the sake of custom-ascertainment to even seek to identify who did (or said) what. The ILC is thus saying that the custom-making moment, because it is presumed, ought not to be traced, named and individualised. Being presumed, the making of CIL can stay anonymous.
The anonymity that accompanies the presumption of the custom-making moment is not benign. In fact, as a result of this anonymity, no one can ever be made responsible for the rule of CIL concerned and what is claimed under its name. In other words, as any customary rule enjoys a life of its own out of time and out of space, what is said under the discourse on CIL cannot be blamed for both the good and the suffering caused in the name of CIL. All those invoking CIL can accordingly present themselves as candid followers and observers who just walk behind CIL, be it for the good or the suffering made in the name of CIL.Footnote 27
4 Concluding Remarks: The End of Foundationalism?
Customary international law epitomizes the idea of grounding. Indeed, by virtue of CIL, the rules to which a customary status is recognised are supposedly grounded in a past social reality. And yet, as has been argued in this chapter, such grounding can never be traced but can solely be presupposed.
It is submitted at this concluding stage that the question of whether this presumptive grounding of CIL is a satisfactory state of the discourse is irrelevant. It is particularly argued here that foundational debates about whether a customary international law rests on valid or invalid, consistent or inconsistent, legal or illegal, grounded or arbitrary, true or untrue, factual or imaginative foundations are bound to be sterile since the foundations of CIL are condemned to be presumptive.Footnote 28 As was shown by this chapter, venturing into foundational debates about the validity, truth, legality, consistency and factuality of the foundations of CIL is to condemn oneself to an inevitable defeat.
Yet, it must be emphasised that the limitations of foundational debates about CIL do not entail that one should verse into relativism, nihilism or even discourse vandalism. Although twenty-first-century post-truth delinquents feel they have made a groundbreaking discovery about the origin-less-ness of discourses, it has long been shown that modern discourses cannot meet their own standards in terms of origins and grounding.Footnote 29 The same holds for international law, and even more so for CIL.Footnote 30 That does not mean, however, that CIL, or all the discourses that cannot meet their own standards of origin and grounding, ought to be derided, disregarded or vandalised.Footnote 31 On the contrary, a discourse should be appreciated for how it does what it does, and especially for its origin-less and untraced performances. In that sense, it is once one is liberated from foundational debates about CIL that one can measure and appreciate both the discursive splendour and the efficacy of the latter.