1. Introduction
International courts and tribunals do not operate in a vacuum. In this era of the ‘jurisdictionalization’ or ‘judicialization’ of international law, a point of law is rarely entirely new and untested.Footnote 1 International courts and tribunals are increasingly conscious of the fact that they operate among peers and do ‘not only decide cases, [but] they [also] cast their shadows’.Footnote 2 Their decisions are, thus, likely to impact the interpretation and application of international law in subsequent cases, and quite often influence the development of international law.
The case law of the International Court of Justice (ICJ or the Court) has had a major impact on other international courts and tribunals. This is not surprising given the unique position of the Court as the only dispute settlement mechanism with general jurisdiction in international law, its long history and permanent character, its aspiration to universality, and its role as the principal judicial organ of the UN.Footnote 3 The Court’s decisions have, thus, naturally influenced the case law of both standing and ad hoc dispute settlement mechanisms, including the International Tribunal for the Law of the Sea (ITLOS),Footnote 4 regional human rights courts,Footnote 5 inter-stateFootnote 6 and investor-stateFootnote 7 arbitral tribunals, and the World Trade Organization (WTO) panels and Appellate Body.Footnote 8 Thus, if the Court’s influence on shaping the jurisprudence of other courts and tribunals is indisputable, the manner in which it treats external case law in its own decisions is of particular interest.
This article examines a specific dimension of the Court’s practice by looking at the ways in which the Court uses inter-state arbitral awards and the authority it attributes to these awards in its decisions. For the purposes of this article, the term ‘authority’ means the weight the Court attributes to these awards in its legal reasoning and how the Court’s consideration of these awards appears to influence the outcome on a given issue before the Court. The authority of judicial and arbitral decisions has received considerable attention both in domestic and international legal scholarshipFootnote 9 and various theories have been presented.Footnote 10 At the risk of oversimplifying, there are legal formalist approaches (reducing the authority to the binding character of the decision as such), normative approaches (measuring authority against some ideal or quasi-ideal characteristics of an institution), sociological approaches (focusing on social aspects of the institution’s legitimacy and its perception by the relevant stakeholders and the public at large), and compliance-oriented approaches (focusing on the implementation of decisions and thus the effectiveness of an institution’s output). Elements taken from each of these approaches contribute to a comprehensive understanding of the Court’s practice of citing any external case law, including arbitral awards. However, the scope of this article is limited to identifying the specific reasons that, in the author’s view, appear to have informed the Court’s choice to expressly refer to inter-state arbitral awards on the basis of a quantitative and qualitative analysis of the decisions in which such references have been made.
As a starting point, it is important to keep in mind that the Court is under no obligation to make reference to arbitral awards, and indeed it very rarely did so before the 1990s. The traditional reluctance of the Court to cite any external case law in its reasoning, or what Thirlway even called an ‘unwritten rule’ not to do so, is visible in the period following the Court’s establishment in 1945 until approximately the 1980s.Footnote 11 According to de Visscher ‘[t]he rarity of such references [was] a matter of prudence; the Court [was] careful not to introduce into its decisions elements whose heterogeneous character might escape its vigilance’.Footnote 12 In reality, one can only speculate why the Court avoided making such references at that time. For instance, it may have been motivated by a desire to reinforce the authority of the Court vis-à-vis the jurisprudence of other courts and tribunals. The Court may equally have avoided making reference to a particular award because of the ad hoc character of the arbitral tribunal that had rendered the award, the composition of that arbitral tribunal, a lack of compliance with the award by the parties, or simply because that award had not been raised by the parties in their pleadings. Since the 1990s, however, a significant number of decisions have been identified by the author in which the Court has relied on arbitral awards where it could have either disposed of the issue by reference to its own case law or without reference to any case law, focusing instead on the relevant treaties or customary international law. Even more striking are those instances among the decisions so identified where the Court refers only to an arbitral award without a parallel citation to its own case law where it could have done so. In this author’s view, these examples suggest that the Court attributes considerable authority to arbitral awards in its reasoning, well beyond their subsidiary role in the classic theory of sources in international law.Footnote 13 In other words, the Court treats them as ‘sufficient authority for the principle under consideration’,Footnote 14 in a manner that is similar to how it treats its own case law.
Writing in 1992, Gray and Kingsbury posited that a principal difference between the respective roles of inter-state arbitral tribunals and the ICJ concerned ‘the relative importance of arbitral awards and of [ICJ] judgments and opinions in the development of rules and principles of international law’.Footnote 15 This article casts at least some degree of doubt on that proposition in light of the Court’s use of arbitral awards in its more recent jurisprudence. It shows that since 1992 both the number of references to arbitral awards and their apparent authority insofar as the Court’s reasoning and the outcome of a particular case is concerned have increased significantly. Despite the growing literature on citation practices among international courts and tribunals, the ICJ’s practice of referring to external case law, and in particular to inter-state arbitral awards, has not yet been studied in sufficient detail and the discussion of its normative repercussions is limited in the existing scholarship.Footnote 16
This article posits that the Court has thus far referred to arbitral awards for three discernible reasons, namely to: (i) determine the existence of a given rule of law; (ii) supplement its reasoning, often already based on its own case law, with other legal authorities; and (iii) distinguish the reasoning found in an arbitral award from the case before it. The manner in which the Court refers to inter-state arbitral awards resembles what one might expect to see in legal reasoning based on the notion of precedent. While there is no doctrine of binding precedent (stare decisis) in international law, and the Court is not obliged to justify what role an earlier arbitral decision may or may not have played in its decision-making, it is argued that the Court treats arbitral awards on point as persuasive precedent. That means that the Court either voluntarily follows them, takes them into consideration or distinguishes their reasoning (rationes decidendi) from the case in hand, without being formally obliged to do so.Footnote 17
Section 2 below discusses the normative framework for evaluating the authority of judicial and arbitral decisions on subsequent cases. Section 3 deals with the use of arbitral awards by the Court and the reasons for which the Court appears to have relied on arbitral awards in its jurisprudence. Section 4 considers the ICJ’s citation of arbitral awards as part of the increasing openness of the Court to external case law. Section 5 summarizes the conclusions of this analysis. Finally, the annex to this article contains a table that lists all the inter-state arbitral awards cited in the ICJ’s case law, as identified by the author.
2. Judicial and arbitral decisions in the doctrine of sources of international law
This section situates judicial and arbitral decisions within the traditional doctrine of the sources of international law in order to identify their legal authority. In principle, these aspects should be settled – judicial and arbitral decisions are not an independent source of obligations for states, other than the parties to the dispute.Footnote 18 In view of the clear language of Articles 38(1)(d) and 59 of the ICJ Statute, judicial and arbitral decisions may at best constitute material evidence of the law, but they do not qualify as formal sources of international law.Footnote 19 While the formal sources (i.e., conventions, custom and general principles) provide in and of themselves validation of the rules they set out, material sources (i.e., judicial and arbitral decisions) only provide evidence of a rule.Footnote 20 However, on occasion, the Court’s reliance on a given judicial or arbitral decision appears to have been sufficient on its own to validate a particular rule of law, even where that rule may not (yet) have been settled in either treaty or customary international law. The fundamental distinction between formal and material sources is thus weakened in practice, particularly where a judicial or arbitral decision is relied upon as the sole basis for the rule in question.
2.1 The legal authority of judicial and arbitral decisions under the Court’s Statute
By contrast to treaties, customary international law and general principles, ‘judicial decisions and the teachings of the most highly qualified publicists’, as they are referred to in Article 38(1)(d) of the Statute of the Court, constitute subsidiary means for the determination of rules of law. This provision is frequently, if not universally, treated as the starting point for the identification of the applicable rules of law. There appears to be broad agreement in the literature on two points concerning the scope of this provision. First, based on the discussions held during the elaboration of the Statute of the Permanent Court of International Justice (PCIJ), the reference to ‘judicial decisions’ in Article 38(1)(d) encompasses arbitral awards.Footnote 21 Second, past judicial and arbitral decisions carry greater weight than the writings of publicists.Footnote 22 The position is best expressed by Fitzmaurice:
[w]hen an advocate before an international tribunal cites a juridical opinion, he does so because it supports his argument, or for its illustrative value, or because it contains a particularly felicitous or apposite statement of the point involved, and so on. When he cites an arbitral or judicial decision he does so for these reasons also, but there is a difference — for, additionally, he cites something which the tribunal cannot ignore, which it is bound to take into consideration and (by implication) which it ought to follow unless the decision can be shown to have been clearly wrong, or distinguishable from the extant case, or in some way legally or factually inapplicable. Equally the tribunal, while it may well treat juridical opinion as something of interest but of no direct authority, and which the tribunal is free to disregard, will not usually feel free to ignore a relevant decision, and will normally feel obliged to treat it as something that must be accepted, or else — for good reason — rejected, but which must in any event be taken fully into account.Footnote 23
Thus, considering the weight attributed to judicial and arbitral decisions in the practice of international law, it may, to borrow the words of the former President Jennings, seem ‘surprising that relatively so little has been done to elaborate principles governing the use of precedents in international law’.Footnote 24 The basic sentiment evidently underlying this comment has been picked up in more recent scholarship that considers the doctrine on sources to be outdated, incomplete, or too rigid.Footnote 25 In fact, international legal scholarship has only recently started examining the influence that judicial and arbitral decisions have had on subsequent cases and the evolution of international law through empirical studies of citation practices in the context of various courts and tribunals.Footnote 26
The practical reality is such that once a judicial or arbitral decision has been rendered, it is unrealistic to expect that a party to a dispute pleading on a similar legal point before another court or tribunal will completely ignore that decision. It is even more unrealistic to expect that the Court or an arbitral tribunal, whether upon the party’s request or proprio motu, would not at least consider that decision. The publication of and instant access to judicial and arbitral decisions has also greatly increased their visibility in subsequent disputes. As Shahabuddeen remarks:
although any given international tribunal is adjudicating only as between the parties before it, it is at the same time functioning as an expression of the legal norms of the larger international community; it is these norms which ultimately assign legal value to the decision of the tribunal.Footnote 27
The authority of a decision rendered by a competent international court or arbitral tribunal thus exerts on the members of the international community a certain pressure that an analogous legal question should be disposed of in an analogous manner.Footnote 28
2.2 The Court’s use of its earlier decisions
The present analysis of the Court’s references to its own decisions reveals that it is not always clear if a decision has been cited as an expression of a rule or principle, or as secondary evidence of the existence of that rule or principle. However, it is clear that earlier ‘decisions are frequently used to identify or elucidate a rule of the law, not to make such a rule, i.e. not so much in the quality of binding precedents as having persuasive influence’.Footnote 29 As Judge Crawford suggests ‘[a] coherent body of previous jurisprudence will have important consequences in any given case. Their value, however, stops short of [binding] precedent as it is understood in the common law tradition’.Footnote 30 This follows, inter alia, from the travaux préparatoires of Article 59, ‘which was not intended merely to express the principle of res judicata, but rather to rule out a system of binding precedent’.Footnote 31 However, it is important to carefully distinguish these two notions. While the object of the principle of res judicata is to prevent the transposition of a binding effect of the operative part of a judgment to any subsequent disputes, the legal reasoning contained in that judgment is not thereby deprived of its character as a persuasive precedent.Footnote 32 To borrow the reasoning of Lord McNair, Article 59 has not ‘hampered the operation of the natural process of looking to previous decisions for guidance in the solution of similar problems’.Footnote 33
In addition, the absence of a formal rule of binding precedent in the Statute of the Court, and in international law more generally, does not undermine the quest for certain consistency and predictability in the jurisprudence.Footnote 34 The need for consistency in the jurisprudence derives from the Court’s awareness that like cases should be settled alike unless there are compelling reasons to depart from previous rulings. The evidence of the Court’s concern with the consistency of its jurisprudence can be traced to the early years of its predecessor, the PCIJ. For example, when rendering its advisory opinion in the Question of the Monastery of Saint-Naoum, the PCIJ found that an issue before it concerning the legal status of a decision of the Conference of Ambassadors which had been instituted under certain post-War treaty arrangements ‘closely resembl[ed]’ and had already been examined in its earlier advisory opinion on the Jaworzina.Footnote 35 More generally, the PCIJ held that it had ‘no reason to depart from a construction which clearly flows from the previous judgments the reasoning of which it still regards as sound’.Footnote 36
The Court’s preoccupation with the consistency of its jurisprudence is also visible in its earliest decisions and the manner in which it treated the decisions of the PCIJ. For example, in the Conditions of Admission of a State to Membership in the United Nations (Article 4 of Charter), the Court stressed that it should not ‘deviate from the consistent practice of the Permanent Court of International Justice, according to which there is no occasion to resort to preparatory work if the text of a convention is sufficiently clear in itself’.Footnote 37 Likewise, in the Barcelona Traction case, the Court relied on several PCIJ decisions concerning acceptable justifications for joining preliminary objections to the merits.Footnote 38 In the words of the former President Winiarski, the Court ‘often seeks guidance in the body of decisions of the former Court, and the result is a remarkable unity of precedent, an important factor in the development of international law’.Footnote 39
In light of the findings in this article, it is interesting to note that the Court’s references to its own jurisprudence have also increased in number.Footnote 40 A recent empirical study conducted by Alschner and Charlotin describes the growing complexity and diversity of the Court’s self-citation practices and the authors conclude that the Court has become increasingly deferential to the authority of its past decisions, ‘thereby asserting its continued importance in an environment marked by the proliferation of adjudicatory institutions’.Footnote 41 The Court’s decisions are replete with statements such as: the Court ‘sees no reason to vary the conclusion it arrived’ at in its previous decision,Footnote 42 or that it is ‘drawing upon’ and shall ‘apply in the present case’ tests formulated in its previous decision.Footnote 43 Elsewhere, the Court has explicitly stated that its decision might constitute ‘precedents to be followed in comparable cases’Footnote 44 or that it has reached a particular conclusion in view of its previous jurisprudence.Footnote 45
It is true that ‘[t]he ICJ, like every court, hesitates to overrule former pronouncements; quite to the contrary, it often refers to previous decisions and to reasons developed in such decisions’.Footnote 46 This is not only ‘indicative of the Court’s judicial consciousness’Footnote 47 but also serves the interests of predictability and consistency in the settlement of disputes, an important factor for continuing reliance by states on the existing means of peaceful settlement of disputes. Indeed, ‘the fact that the doctrine of binding precedent does not apply … does not mean that [the decisions of the Court] are not “precedents”’.Footnote 48 The precedential value of the reasoning in a given adjudicatory decision goes far beyond the legal authority that a given legal system attributes to such decision. As Lauterpacht emphasized, the Court follows its own decisions:
because such decisions are repository of legal experience to which it is convenient to adhere; because they embody what the Court has considered in the past to be good law; because respect for decisions given in the past makes for certainty and stability, which are of the essence of the orderly administration of justice; and (a minor and not invariably accurate consideration) because judges are naturally reluctant, in the absence of compelling reasons to the contrary, to admit that they were previously wrong.Footnote 49
At the same time, the fact that the Court has built and conceptualized the idea of its settled jurisprudence (jurisprudence constante)Footnote 50 does not mean that it cannot reconsider issues that it has dealt with before, as the evolution of the case law in the area of maritime delimitation demonstrates so well,Footnote 51 or yet the more recent and highly controversial departure by the Court from its longstanding legal test as to the existence of the dispute.Footnote 52 This demonstrates the Court’s flexibility when confronting its earlier decisions but at the same time any such departures from earlier decisions are, at least in principle, subject to a rather high threshold test of ‘compelling reasons’.Footnote 53
In light of the above, one can conclude that the restrictive provisions of the Court’s Statute on the treatment of past decisions have not prevented it from treating its decisions as having an authority akin to persuasive precedent. For the ‘consistent invocation of arguments of principle through a series of judicial decisions anchors those decisions within a broader legal scheme, and provides a coherent justification for the legal order itself’.Footnote 54 When settling a dispute, every court and tribunal (including the Court) requires an understanding of the legal framework in which its judgment is being drafted, including whether the issues similar to those in dispute have already been addressed by others. As rightly pointed out by Jia, ‘an attendant doctrine of precedent is inherent in a functional system of adjudication’.Footnote 55 The Court’s recurrent citation of its previous case law contributes to maintaining and promoting the authority of its decisions and consolidating a particular interpretation of the rules as applied by the Court. The same holds true in respect of the Court’s use of inter-state arbitral awards, as discussed in the next section.
3. The Court’s use of inter-state arbitral awards
3.1 Methodological choices
As indicated above, the scope of this article is limited to the Court’s use of inter-state arbitral awards and does not therefore seek to analyse the Court’s use of other external case law, such as that of ITLOS,Footnote 56 international criminal tribunals,Footnote 57 regional human rights courts,Footnote 58 and committees set up under various human rights conventions.Footnote 59 There are several reasons for this. First, while inter-state arbitral awards represent only one category of external case law which the Court has referred to in recent years, it is by far the most frequently cited external authority in the Court’s decisions. For example, while the Court has twice referred to the ITLOS Bangladesh/Myanmar judgment and has cited a handful of human rights cases in its Diallo judgment and the Wall advisory opinion, some of its most recent judgments contain as many as six citations to different arbitral awards.Footnote 60 Second, inter-state arbitral awards are functionally similar to the Court’s case law. They are subject to similar jurisdictional constraints and address similar substantive and procedural points of law, whereas the same is not true of the investor-state, human rights or international criminal law decisions, to which the Court may also make reference on occasion. Indeed, until rather recently, the ‘Court’s policy of precedent essentially aim[ed] to assure a constructive dialogue with arbitration tribunals dealing with interstate disputes, primarily in border disputes’.Footnote 61 As we shall see, it is naturally still the case that the majority of the Court’s references to arbitral awards occur in the field of territorial sovereignty and maritime delimitation. However, with the expansion in the variety of its docket, the Court has also increasingly referred to inter-state arbitral awards for other questions of substance and procedure in international law.
In particular, the Court’s reliance on inter-state arbitral awards and their growing authority in the Court’s decisions may be contrasted with the absence of similar reliance on investor-state arbitral awards, notwithstanding their volume, the level of interest in them, and the areas of substantive overlap.Footnote 62 In fact, the Court has recently explicitly dismissed, albeit briefly, the relevance of arbitral awards in investor-state arbitration to its assessment of whether the doctrine of legitimate expectations exists in general international law.Footnote 63 Similarly, the Court does not appear to have accorded much value to decisions of municipal courts in their own right, except when using those decisions collectively to ascertain the existence or scope of a given rule under customary international law.Footnote 64
Before proceeding with the discussion of the authority of arbitral awards, three points on the methodology of the analysis underlying this article are in order. First, this analysis does not consider whether there is a correlation between the citation of an arbitral award by the Court and the pleadings of the parties. Indeed, there are many cases where the parties have cited dozens of arbitral awards in support of their contentions, but no award was ultimately referred to in the body of the Court’s judgment.Footnote 65 Second, this analysis has not considered references to arbitral awards in the sections of the Court’s decision that summarise the parties’ arguments without explicitly relying on, engaging with or distinguishing the reasoning of those awards.Footnote 66 Third, cases in which a specific arbitral award constituted the object of the dispute (i.e., those cases in the Court’s history relating to the validity or interpretation of an arbitral award) have been excluded as they do not shed light on the phenomenon of the Court’s use of arbitral awards as an authority for certain legal propositions.Footnote 67 These methodological choices assist in distilling the actual authority of an arbitral award in the eyes of the decision-maker, i.e., its weight on the reasoning and/or outcome of the Court’s decision, as opposed to its use by the parties in support of their contentions or as the very object of the case before the Court.
3.2 Findings
References to inter-state arbitral awards in the Court’s decisions are by no means new, but their frequency and the weight given to them in the Court’s legal reasoning and the outcome of the decision have increased over time. While references to arbitral awards were already made in the decisions of the PCIJ, it rarely cited specific arbitral awards and preferred to make generic allusions to arbitral jurisprudence.Footnote 68 In contrast to the PCIJ’s predominantly broad and generic references to unspecified arbitral jurisprudence, the ICJ’s decisions contain specific and explicit references to arbitral awards.Footnote 69
In the period between 1946 and 1982, only a single reference to an arbitral award can be found in the Court’s decisions.Footnote 70 Likewise, between 1982 and 1992, only three decisions of the Court cited an arbitral award.Footnote 71 However, in stark contrast, from 1992 onwards there has been a marked increase in references to arbitral awards in the body of the ICJ’s decisions, both quantitatively (17 decisions of the ICJ citing 24 different inter-state arbitral awards) and qualitatively, i.e., in terms of their actual authority reflected in the legal reasoning and the decision of the Court.Footnote 72 The fact that the Court has cited inter-state arbitral awards in 21 (or 13%) of its decisions may not seem so significant in light of the Court’s caseload from 1946 to date (i.e., 159 decisions, or 131 judgments and 28 advisory opinions). However, it is the change in this practice over time that is of importance. While between 1946 and 1991, only 5 per cent of the Court’s 77 decisions (56 judgments and 21 advisory opinions) contained a reference to at least one inter-state arbitral award, since 1992, this has increased to 20 per cent of the Court’s 86 decisions (79 judgments and seven advisory opinions). While the Court’s caseload as a whole has also increased over this time, this increase alone does not explain the quantitative and qualitative change in the Court’s treatment of arbitral awards.
In fact, more than two thirds of the Court’s decisions that expressly refer to arbitral awards were issued after 1992. De Brabandere attributes this shift to, inter alia, the more frequent publication of arbitral awards and the fact that the ICJ has in recent cases, been confronted with issues that have already been decided by arbitral tribunals.Footnote 73 Another reason for this shift is the renaissance of inter-state arbitration since the late 1990s, in particular after the entry into force of the UNCLOS in 1994 providing for arbitration as the default dispute settlement mechanism under Part XV thereof.
It is only natural that some awards have appeared more often and prominently than others in the jurisprudence of the Court. For instance, the Delimitation of the Continental Shelf (UK v. France), Guinea v. Guinea-Bissau and the Island of Palmas awards have been mentioned numerous times each in the Court’s jurisprudence, often as a subsidiary but sometimes as the sole authority for a given proposition. This can be partly explained by the content of the Court’s docket, which until quite recently was dominated by disputes relating to territorial sovereignty and maritime delimitation. This also explains the relative paucity of arbitral awards cited by the Court in other areas of international law, though the practice is still present in the Court’s decisions on the law of treaties,Footnote 74 state responsibility,Footnote 75 and other matters.Footnote 76 Interestingly, judges in their individual opinions have relied on a wider set of arbitral awards, including on other issues such as the use of experts,Footnote 77 estoppel,Footnote 78 res judicata,Footnote 79 the effect of provisional measures,Footnote 80 questions of evidence,Footnote 81 non liquet,Footnote 82 the principle of the free navigation of rivers,Footnote 83 the question of elementary considerations of humanity and reprisals,Footnote 84 questions of nationality of legal and physical persons,Footnote 85 equity,Footnote 86 compensation for non-material damages,Footnote 87 the obligation of due diligence,Footnote 88 the obligation to conduct environmental impact assessments,Footnote 89 and the requirement of the exhaustion of local remedies.Footnote 90
Several criteria can be used to evaluate the authority of awards cited in the Court’s jurisprudence and more generally their impact on the development of international law. These criteria have been preliminarily tested and developed elsewhere, and include the status of arbitrators (for example, is an award more likely to be cited because the arbitrators are well known in international law or are current or former judges at the Court), unanimity of the decision, and compliance with the award.Footnote 91 Over the past few decades, numerous judges of the Court either had participated as counsel or sat as arbitrators in inter-state arbitrations, dealing with substantive and procedural issues similar to those that regularly arise in the context of the ICJ proceedings. For example, Judge Guillaume, former President of the Court, was counsel to France in the Air Services arbitration, and it could be argued that this is why the Court cited that award in the Gabčíkovo-Nagymaros judgment on the question of countermeasures. Likewise, Judges Jennings, Schwebel and Higgins all sat on the Eritrea v. Yemen tribunal and, again, it could be argued that this is what may explain the reference to this award in the reasoning of the Court in the Maritime Delimitation in the Black Sea case, the last judgment rendered under the presidency of Judge Higgins. This kind of inquiry is beyond the scope of this article, which does not seek to analyse such extra-legal considerations. In any event, the possible role played by such sociological factors is likely to be outweighed by more obvious factors that play a role in the identification of relevant decisions.
What then actually prompts the Court to refer in its legal reasoning to any external precedent? There are at least four basic reasons which, perhaps unsurprisingly, are similar to those which may explain the Court’s practice of citing its own jurisprudence. First, there is the proposition that the Court would not reinvent the wheel in the presence of a clear precedent.Footnote 92 Rosenne for example notes that:
some of the citations [in the Court’s decisions] are little more than a form of incorporation by reference to previous statements, a technical feature of judicial composition which lends itself to the elliptical phrasing so characteristic of contemporary international judgments.Footnote 93
However, the Court may not be able to find the best precedent in its own jurisprudence, leading to the citation of an arbitral award. Second, as argued by Jia:
[i]n the course of judicial settlement or arbitration, the international adjudicators, by training and, where relevant, the will of the parties, refer to, rely on, or distinguish decisions from tribunals, courts, and claims commissions, including early decisions of their own, so that they can reach an authoritative decision that the parties are expected to accept and implement.Footnote 94
In other words, it is in the Court’s interest to cite any relevant cases, where appropriate, as the corresponding discussion may further bolster the authority of its decision or of its settled jurisprudence in a particular area of law. Third, it may simply be the case that the parties have built their argumentation exclusively on a particular precedent, and the Court feels compelled to address it. Fourth, the Court’s inclination to favourably or unfavourably cite an arbitral award may be explained by its perception of its role in the community of courts and tribunals, particularly if the legal question at stake is one of principle.
Beyond these generic reasons for referring to an earlier precedent, through the analysis of 24 cases of the PCIJ and the ICJ in which arbitral awards have been cited in the reasoning of the Court, three specific reasons for which they have been used have been identified: (i) to determine the existence of a given rule of law; (ii) to supplement other legal authorities for a given proposition or the settled jurisprudence of the Court; and (iii) to distinguish the rationale of an arbitral award from the case before the Court. These reasons are not exhaustive nor beyond reproach, but they provide a framework for analysing the Court’s practice of referring to arbitral awards.
3.2.1 Determining the existence of a given rule of law
In its decisions, the Court has often referred to arbitral awards when determining the existence of a given rule of law. In this context, the Court appears to have used arbitral awards both as a subsidiary means of determining the existence of a particular rule of law and sometimes as a representative expression of a given rule or principle.
First, there are decisions in which the Court has referred to an arbitral award as a subsidiary means for determining the rule of law, including rules of treaty law or of customary international law. For example, in the Gulf of Maine case, the Chamber referred to the Delimitation of the Continental Shelf (UK v. France) arbitral award to show that the application of equitable principles in the context of maritime delimitation was consistent with customary international law as it existed at that time.Footnote 95 Similarly, in Territorial and Maritime Dispute (Nicaragua v. Colombia), the Court could have simply referred to the rule that a state is entitled to 12 nautical miles of territorial sea around islands, as stated in Articles 3 and 121(2) UNCLOS, but instead demonstrated that the same rule has been consistently applied by arbitral tribunals by reference to a number of arbitral awards.Footnote 96 These are examples of the use of arbitral awards that are consistent with Article 38(1)(d) of the Court’s Statute.
Second, and more controversially, the Court has occasionally referred to an arbitral award as a representative expression of a given rule or principle of international law. It has often done so without adducing, at least expressly, any other evidence for the existence of the underlying rule or principle of international law. For example, in the Maritime Delimitation in the Black Sea (Romania v. Ukraine) and Territorial and Maritime Dispute (Nicaragua v. Colombia) cases, the Court relied solely on the Barbados v. Trinidad and Tobago award to discard resource-related criteria as a relevant circumstance in the context of maritime delimitation.Footnote 97 In the Territorial and Maritime Dispute (Nicaragua v. Honduras), the Court quoted Guinea v. Guinea-Bissau award as the sole precedent both for the use of the bisector method of delimitation, thereby departing from its previously consistent use of a median line, and for the placement of the point of departure of the delimitation line seaward.Footnote 98 Likewise, in Sovereignty over Pulau Ligitan and Pulau Sipadan (Indonesia/Malaysia), the Court ruled that it could not take into account effectivités subsequent to the critical date (i.e., the date at which the dispute crystallized), relying solely on the Palena arbitration award in support of that approach.Footnote 99 In Maritime Delimitation and Territorial Questions (Qatar v. Bahrain), the Court when analysing Fasht al Jarim, a maritime feature partly situated in the territorial sea of Bahrain, referred to the Delimitation of the Continental Shelf (UK v. France) award in relation to its conclusion that if in the process of delimitation that feature were to be ‘given full effect, [it] would “distort the boundary and have disproportionate effects”’.Footnote 100 As a result, the Court gave no effect to this feature in determining the boundary line.Footnote 101
The Court has also referred to arbitral awards as a sole authoritative basis in areas other than territorial sovereignty or maritime delimitation. For example, in the Kasikili/Sedudu case, by only relying on the precedent of the Laguna del desierto award, the Court ruled that ‘there [was] nothing that prevent[ed] the Court from taking into account the present day state of scientific knowledge’ in interpreting a given treaty.Footnote 102 Similarly, in the Diallo compensation judgment, the Court relied solely on the Lusitania awards as a direct authority for the proposition that moral damages are compensatory and that their quantification relies on equitable considerations.Footnote 103
In other words, the Court uses not only its own case law but also arbitral awards as a shortcut to assert that a particular rule is well-established in international law.Footnote 104 As noted by former President Jennings, often ‘[t]he difficulty of deciding what the customary law is, can only add authority to a judicial decision resulting from the careful consideration and weighing of such materials’.Footnote 105 Examples of this use of arbitral awards by the Court are significant to the extent that they show the inductive authority of an arbitral award on the Court’s reasoning and the outcome of its decision on a given issue at dispute. The Court has gone as far as to use an arbitral award as the sole authority for the existence of a particular rule or principle, without searching for further evidence of that rule in treaty or customary international law.Footnote 106 This shows that the Court may have, at least on occasion, made use of arbitral awards beyond the purely subsidiary role that is attributed to them by Article 38(1)(d) of the Court’s Statute. Indeed, it would seem that arbitral awards have become ‘a most important factor in the development of international law, and the[ir] authority and persuasive power … may sometimes give them greater significance than they enjoy formally’.Footnote 107
3.2.2 Supplementing legal reasoning
The authority attributed by the Court to arbitral awards is further demonstrated by instances where the Court could have disposed of a particular point by referring to its own jurisprudence but relied instead on an arbitral award. Such instances may even demonstrate that the Court considers the award in question to have supplemented the Court’s earlier finding insofar as the rule or principle of international law at issue is concerned.
By using arbitral awards to supplement its reasoning, the Court may also seek to bolster its settled jurisprudence. For instance, in the Pedra Branca/Pulau Batu Puteh case, the Court addressed evidence that may establish that there has been a continuous and peaceful display of authority, as well as the circumstances that may lead to the loss of title. To that end, the Court relied on the Island of Palmas case, even though a treatment of its own precedents from the Eastern Greenland and the Temple of Preah Vihear cases arguably would have sufficed insofar as its reasoning was concerned.Footnote 108 It also looked to arbitral awards in Land and Maritime Boundary (Cameroon v. Nigeria), to consider that on balance the arbitral case law definitively confirms that oil concessions and oil wells do not constitute as such a relevant circumstance justifying the adjustment of the provisional equidistance line.Footnote 109 Most recently, in its judgment in the joined cases concerning Maritime Delimitation in the Caribbean Sea and the Pacific Ocean and Land Boundary in the Northern Part of Isla Portillos, the Court referred to the arbitral award in the Bay of Bengal Maritime Boundary (Bangladesh v. India) arbitration as confirmation that the three-stage delimitation methodology set out by the Court in 2009 has been consistently adopted by other courts and tribunals. Footnote 110
On other occasions, the Court simply listed arbitral awards alongside its own jurisprudence, without more. That was the case in Gabčíkovo-Nagymaros Project, where the Court cited Air Services award alongside its own case law when determining whether Slovakia’s act of putting the so-called ‘Variant C’ alternative into operation and thereby diverting the waters of the Danube, constituted a lawful countermeasure.Footnote 111
Finally, the Court has occasionally referred to a rule set out in its own jurisprudence but deemed it appropriate to refer to more specific applications of that rule in arbitral awards. For example, in the Application of the Interim Accord, the Court, while citing the North Sea Continental Shelf and Fisheries cases, highlighted several additional conditions and elements for the requirement of negotiations in good faith as applied by arbitral tribunals in the Lac Lanoux and Tacna Arica arbitrations.Footnote 112 These arbitral awards contained more specific guidance as to the kind of conduct that has been found to constitute bad faith or which would frustrate any further negotiation efforts. These references allowed the Court to set out more clearly the content of the obligation to negotiate in good faith and assess whether it had been complied with in the case before it.Footnote 113
3.2.3 Distinguishing arbitral awards from the case before the Court
The Court has also used arbitral awards in order to distinguish the decision in those awards from the issues before it. This is something it would not need to do if it did not consider the awards to have some form of authority above that of subsidiary means for the determination of the rules of law. As eloquently pointed out by Shahabuddeen, ‘[t]he art of distinguishing is of course the trademark of a system of precedents’.Footnote 114 For instance, in Barcelona Traction, the Court stated that it had considered a number of arbitral awards that had been cited by the parties, but found that those awards did not give rise to any general rule because they turned on the terms of the underlying agreements to arbitrate.Footnote 115 Likewise, in Land and Maritime Boundary (Cameroon v. Nigeria: Equatorial Guinea intervening), the Court noted that while the concavity of the coastline may be a circumstance relevant to delimitation as found in the Guinea v. Guinea-Bissau award, this will only be the case ‘when such concavity lies within the area to be delimited’ which was not the case in the dispute before the Court.Footnote 116 In the same judgment, the Court considered it necessary to distinguish two arbitral awards in which the tribunals had considered administrative activities to be relevant effectivités. In particular, the Court reasoned that, in contrast to the Rann of Kutch (India v. Pakistan) and Beagle Channel (Argentina v. Chile) awards, Nigerian administrative activities in the Bakassi peninsula had not been used to support the existence of a legal title, but rather had been conducted contra legem. Footnote 117 Similarly, in the Gulf of Maine case, the Court meticulously distinguished the Grisbådarna award from the circumstances of the case before it, holding that:
it is not possible to conclude, on the basis of the Grisbådarna precedent, from a comparison of the conduct of Sweden and Norway with that of the Parties to the present case, that the conduct of the United States was sufficiently clear, sustained and consistent to constitute acquiescence.Footnote 118
The Court ultimately concluded that ‘[t]he differences between the two cases [were] so great that it is difficult to establish a parallel between them’,Footnote 119 yet without questioning the continuing legal relevance of that award.
In all the above cases, the parties had expressly referred to the arbitral awards in question in support of their arguments, which may have prompted the Court to justify their non-applicability to the circumstances of the extant case. Interestingly, the Court has never sought to undermine the validity of the rule or principle set out in such awards. Rather, it has focused on justifying why it should not be applied to the case before it. This suggests that the Court considers such arbitral awards to be valid and sufficiently authoritative to make it necessary to distinguish them; it would not do so out of politeness.
4. The Court’s openness to inter-state arbitral awards
In the author’s view, several of the findings described above demonstrate that the Court considers arbitral awards, alongside its own judgments, to carry persuasive authority for the Court’s decision-making and international law as a general matter. These findings concern the number of citations by the Court to arbitral awards in the last three decades, the variety of substantive and procedural issues for which the Court has looked to arbitral awards, and the cases where the Court could have disposed of an issue by relying on its own jurisprudence but resorted instead (or additionally) to arbitral awards.
By being open to relying on arbitral awards, the Court has also contributed to the consolidation of certain rules and development of others. Judicial and arbitral decisions incrementally develop the law and ‘inject much-needed normativity into [international relations] in the interest of stability, predictability, and confidence’.Footnote 120 As Jia rightly points out ‘[b]y accepting judicial and arbitral decisions states modify and adjust their policies and behaviour, leading to new trends in practice or even new rules of law’.Footnote 121 The ways in which the Court has been using arbitral awards in its judicial practice confirms Judge Guillaume’s view that ‘recourse to precedent is a necessity’.Footnote 122 However, this recourse to precedent is no longer an inward-looking process. Instead, it is an increasingly outward-looking process. This lends direct support to the idea that international dispute settlement ‘creates and shifts actors’ normative expectations and as such develops legal normativity’.Footnote 123
The increasing reference by the Court to arbitral awards also shows that the Court is willing to engage in a more open dialogue between judges and arbitrators, perhaps with due regard to its role as a guardian of the consistent application and interpretation of international law. By citing a given arbitral award, the Court shows that it is aware of how a given rule has been applied by other courts and tribunals, and it seeks thereby to garner support for the recognition of an acceptable interpretation or application of that rule. This is particularly apparent in some of the recent judgments. The example discussed above of the reference in Maritime Delimitation in the Caribbean Sea and the Pacific Ocean/Land Boundary in the Northern Part of Isla Portillos, to the Bay of Bengal award is apposite, not only in respect of the three-stage methodology to maritime delimitation but also in respect of the criteria for determining the relevant coasts.Footnote 124 Similarly, the numerous citations of arbitral awards and judgments of ITLOS in Territorial and Maritime Dispute (Nicaragua v. Colombia) shows the Court’s concern with maintaining the coherence of jurisprudence in the context of maritime delimitation, such as in respect of the circumstances in which exceptions to the general rule that islands are entitled to a 12 nautical mile territorial sea may be justified.Footnote 125
Finally, the Court’s openness to inter-state arbitral awards gives rise to a form of dialogue as modern inter-state arbitral tribunals consistently refer with approval to the Court’s judgments.Footnote 126 What is more, many recent inter-state arbitral awards cite ICJ decisions and earlier arbitral awards together, without any authoritative distinction being drawn between them.Footnote 127 While the dialogue between the ICJ and arbitral tribunals may not always be balanced, the cross-referencing of case law is definitely a positive start. Such a dialogue signals a maturing of the international legal system, even if it lacks a vertical structure and hierarchy among courts and tribunals.Footnote 128 As rightly pointed out by Clapham:
[w]hen an system of law has reached a stage at which it is thought worthwhile to report the decisions and the reasoning of judges, other judges inevitably give weight, though not necessarily decisive weight, to the work of their predecessors or colleagues.Footnote 129
5. Concluding remarks
This article has shown that inter-state arbitral awards have made a significant contribution to the development of many areas of international law, albeit on a smaller but increasing scale when compared to the Court’s own jurisprudence. Evidence of that contribution can be found in the three decisions of the PCIJ and 21 decisions of the ICJ (a total of 24 decisions) that refer to 29 different inter-state arbitral awards. In most of these decisions, the references to inter-state arbitral awards appear to have had a significant impact on the Court’s reasoning and the outcome of the case. With the exception of six decisions of the Court and the PCIJ that referred to arbitral awards before 1990s, all other citations of arbitral awards have been made in decisions rendered since 1992.
The author has identified three specific reasons underlying the Court’s practice of referring to inter-state arbitral awards. The Court has used arbitral awards in order to determine the existence of a given rule, to supplement its legal reasoning or its own case law on a particular point, or to distinguish an arbitral award from the case before it.
The Court has thus moved well beyond being its own echo chamber to participating in a much more open discourse, fostering the cross-fertilization of legal authorities.Footnote 130 It is increasingly the case that:
when the Court decides an analogous case basing itself on principles established in its case law, or even that of arbitral tribunals … the Court is relying on the relevant previous decisions as the justification for the conclusion reached in the analogous case.Footnote 131
Inter-state arbitral awards do not serve as binding precedent but they do appear nevertheless to substantially influence the reasoning of the Court. As we have seen, even where the Court has distinguished an arbitral award, it has never explicitly questioned the validity of the findings in that award.
The findings of this article, while certainly limited in scope, challenge three recurring myths. First, the article shows that, in reality, inter-state arbitral awards, along with judicial decisions, are more than a subsidiary means for the determination of rules of law, as provided for in Article 38(1)(d) of the Court’s Statute. Even if formally the Court is not bound by a relevant arbitral award, in practice it considers it (and tells us that it is doing so) where it is germane to the issue the Court must decide. Second, the article shows that arbitral awards carry similar weight to the Court’s own judgments and at times determine the outcome on a particular point. This is particularly so where the Court has relied exclusively on arbitral award to rule on a given issue before it. Third, the analysis underlying this article shows that, contrary to the concerns primarily in the late 1990s and early 2000s, the proliferation of international courts and tribunals and the fragmentation of international law has not driven the courts and tribunals to become more inward-looking, but quite the contrary. As noted by Judge Greenwood:
International law is not a series of fragmented specialist and self-contained bodies of law, each of which functions in isolation from the others; it is a single, unified system of law and each international court can, and should, draw on the jurisprudence of other international courts and tribunals, even though it is not bound necessarily to come to the same conclusions.Footnote 132
This article has demonstrated that the Court has not only ‘been readier than in the past to mention [arbitral awards] specifically in its reasoning’Footnote 133 but has promoted respect for the rules and principles upheld in these arbitral awards, thereby recognizing their contribution to the development of international law and further promoting a more open judicial dialogue.Footnote 134 This is a true reflection of the evermore demanding task and function of the Court and the increasing complexity of international law today.Footnote 135 We are living in a ‘brave new world’ of authority sharing, where continuity is no longer a matter of a self-contained institutional memory, and it has become necessary to pay greater attention than ever before to authorities originating from other dispute settlement peers that are dealing with similar questions.Footnote 136
Annex: Inter-State Arbitral Awards Cited in the Decisions of the CourtFootnote 1
