Comparative Reasoning in International Investment Law and Arbitration

doi:10.1017/9781009599122.007

3 - Comparative Reasoning in International Investment Law and Arbitration

from Part I - Unity, Diversity, and Evolution of Interpretation across Sources of International Law

Published online by Cambridge University Press: aN Invalid Date NaN

Yannick Radi

Edited by

Sotirios Ioannis Lekkas ,

Nina Mileva and

Panos Merkouris

Edited in association with

Ivo Tarik de Vries-Zou

Show author details

Sotirios Ioannis Lekkas: Affiliation:
University of Sheffield
Nina Mileva: Affiliation:
University of Groningen
Panos Merkouris: Affiliation:
University of Groningen
Ivo Tarik de Vries-Zou: Affiliation:
University of Goningen

Book contents

Summary

International investment law is a regime in search of its identity. At the core of this search, a central role is played by ‘comparativism’ (or comparative reasoning) as a method of interpretation employed by investment tribunals. It explores how comparative reasoning fits into the theory of sources, and how this method is used by arbitral tribunals to convince their audience. The chapter finds that arbitral tribunals regularly rely on customary international law, general principles of law, as well as previous judicial decisions, when interpreting IIAs provisions. However, in doing so, arbitral tribunals display a selectivity in the choice of domestic rules or systems considered for this purpose. Relatedly, when relying on previous judicial decisions, they do not always enquire sufficiently into the similarity (or lack thereof) between the past judicial decisions and the present issue at hand. The chapter concludes that arbitral tribunals rely on comparative reasoning to strengthen or justify the choices made in the course of interpretation.

Keywords

comparativism international investment agreements investment tribunals

Information

Type: Chapter
Information: The Practice of Interpretation in International Law
Unity, Diversity, and Evolution
, pp. 47 - 67

DOI: https://doi.org/10.1017/9781009599122.007 [Opens in a new window]

Publisher: Cambridge University Press

Print publication year: 2026
Creative Commons: This content is Open Access and distributed under the terms of the Creative Commons Attribution licence CC-BY-NC-ND 4.0 https://creativecommons.org/cclicenses/

3 Comparative Reasoning in International Investment Law and Arbitration

3.1 Introduction

International investment law and arbitration is a regime that is in search of its identity. As further explained below, this is well illustrated by the debates across arbitration practice and legal scholarship on technical legal issues and, more generally, on the nature of the system as a whole. At the core of this search, comparativism – which can be broadly defined as an ‘intellectual activity with law as its object and comparison as its process’Footnote ¹ plays an important twofold role.

From a systemic standpoint, comparativism enables stakeholders to build and justify the identity, that is, the legal nature and features, that they intend to confer to the regime. In this respect, it is worth flagging that comparative reasoning is not a neutral process. In that sense, this type of reasoning has been said to be a means to an end rather that an end in itself, an opinion that entails that the politics of these ends are inevitably at work in the choice of analogies.Footnote ² That being said, comparativism has no doubt the potential to overcome that politics in the long run by establishing a ‘transversal’ legal dialogue and discourse that can contribute to conferring an identity to international investment law and arbitration.Footnote ³

From a practical point of view, comparative reasoning is an important tool often used by arbitral tribunals, be it explicitly or implicitly, in order to perform their task. This holds true in particular as regards the interpretation of international investment agreements (IIAs), the determination of customary international law (CIL), and the identification of general principles of law originating from domestic legal orders (GPL).Footnote ⁴ Comparativism has therefore a significant impact on the content-determination of a broad scope of rules pertaining to the substantive protection of foreign investors and to arbitration.

The present chapter focuses on the use of comparative reasoning in the interpretation of – vague – IIA provisions, be they of a substantive or of a procedural nature. Doing so, it also discusses the role played by comparative reasoning with regard to CIL and GPL inasmuch as both sources are relevant in IIAs’ interpretation.

More precisely, the chapter addresses the matter from two perspectives – that is, legality and legitimacy – which are both necessary to capture the diversity of issues that comparativism raises in the field. As for legality, it examines how comparative reasoning fits into the theory of sources and into the canons of treaty interpretation under public international law (Section 3.4). As regards legitimacy, it enquires into the potential of comparative reasoning to help arbitral tribunals convince their audience (Section 3.4). To pave the way for the discussion of those two perspectives, the chapter starts by briefly formulating some remarks on the ‘why’ and ‘what’ of comparative reasoning. It first explains the reasons why comparative reasoning is used in international investment law and arbitration (Section 3.2), before discussing the materials of comparativism in this field (Section 3.3).

3.2 The Reasons for Relying on Comparative Reasoning

There are two main reasons that explain why arbitrators, counsels, and academics conduct comparative reasonings – namely, legal indeterminacy and hybridity. More precisely, hybridity has a twofold dimension, with the interaction between them amplifying this hybridity. The first dimension pertains to the legal nature, features, and components of the regime. The second one relates to the characteristics of the international investment law and arbitration epistemic community. For didactic purposes, those two dimensions are respectively called, in what follows, ‘hybridity ratione materiae’ and ‘hybridity ratione personae’. Both dimensions are discussed in turn before the chapter addresses the issue of legal indeterminacy.

3.2.1 Ratione Materiae Hybridity

As detailed in Section 3.3 in relation to the materials of comparativism in international investment law and arbitration, the nature of this field is disputed among its stakeholders who are involved in dispute settlement. Such a controversy exists also in academia. Face-to-face, one finds in particular the proponents of the ‘public paradigm’ against those who are supporting and promoting the ‘private paradigm’. Whatever the significance of this controversy, it is worth noting that ratione materiae hybridity does not originate only from dispute settlement and legal scholarship. It also proves to be the outcome of law-making in the field. The hybridity that derives from that process has both a synchronic dimension and a diachronic one, both contributing to explaining the use of comparative reasoning in the field.

Looking at the matter from a synchronic standpoint first, it is fair to say that ratione materiae hybridity is not specific to our time. It has always been a feature of international investment law and arbitration. At all the stages of its history, the regime and its component parts have proven to display diversity, a diversity due to the various legal orders and disciplines it has been connected to. Focusing on the genesis of the regime, for instance, such a characteristic is reflected in the sources of rights and obligations.Footnote ⁵ Customary international law, notably the minimum standard of treatment,Footnote ⁶ attached the field to the (public) international legal order. On the other hand, the lex mercatoria connected it to a transnational legal order.Footnote ⁷ The debate about the legal order in which contracts concluded between host states and foreign investors (‘state contracts’) are grounded provides another illustration of the ratione materiae hybridity of the regime at that time.Footnote ⁸ This diversity of the sources of rights and obligations also reveals that hybridity in the field is a consequence of the choice that is left therein to the parties to choose the law applicable to the settlement of their disputes. Unavoidably, the reference to domestic law, international law, or the lex mercatoria leads the regime in different directions. This contributes to its ratione materiae hybridity and, more generally, this encourages or justifies the use of different analogies as part of comparative reasoning.

This ratione materiae hybridity has also a diachronic dimension, which has impacted both IIAs’ substantive rules and the features/nature of the settlement of investor-state disputes. Evolving views and approaches among policymakers have led to evolutions of key components of the substantive protection conferred by IIAs to foreign investors. This has notably been the result of the politics of bilateral investment treaty (BIT) models. European modelsFootnote ⁹ that were originally predominant have later shared the ‘policy floor’ with other models from developed and developing countries.Footnote ¹⁰ All this is well illustrated by the evolution of the expropriation provision. In this respect, it is worth flagging the approach adopted on the matter by the US in their 2004 BIT Model, which,Footnote ¹¹ as regards expropriation, is directly influenced by the case-law of the US Supreme Court.Footnote ¹² Since then, this approach has spread across treaty practice.Footnote ¹³ Such an influence of domestic constitutional law evidences, not only how the regime has developed a ratione materiae hybridity over time but also how – again – this encourages or justifies the use of different analogies as part of comparative reasoning.

Investor-state arbitration, and more generally the settlement of investor-state disputes, has also experienced a ratione materiae hybridity throughout its history. While originally modelled on commercial arbitration and inter-state arbitration, the former being often said to be a ‘private’ type of justice, investor-state arbitration has developed ‘public’ features as of the 2000s. The move away from confidentiality and the increase in transparency, initiated by the International Centre for Settlement of Investment Disputes (ICSID) Secretariat,Footnote ¹⁴ illustrates this diachronic dimension of ratione materiae hybridity. The diversification of the methods used to settle investor-state disputes offers another illustration. This diversification materialises, for instance, in the choice made by some treaty parties to favour ‘the return of the State’Footnote ¹⁵ and to opt for inter-state arbitration at the expense of investor-state arbitration.Footnote ¹⁶ Such a choice has notable consequences as regards the debate about the direct or derivative nature of investors rights and the comparisons that can be drawn (or not), for instance, with international human rights law.Footnote ¹⁷ As it appears here again, all this encourages or justifies the use of different analogies as part of comparative reasoning.

3.2.2 Ratione Personae Hybridity

As mentioned above, this form of hybridity pertains to the international investment law and arbitration epistemic community.Footnote ¹⁸ It allows us to understand and assess how the profile of the members of that community contributes to hybridity in the field and to the reliance on comparative reasoning therein.

As evidenced by the programmes of conferences, the websites of law firms, or the composition of tribunals made public, professionals in the field have a very diverse scientific background. As detailed below in Section 3.3 regarding the discussion of the materials of comparative reasoning, those backgrounds are manifold. This diversity pertains to legal traditions, legal orders, and legal disciplines, which can all vary – according to various combinations – from one of those professionals to the other. Looking at the literature and arbitral practice, it appears that those scientific backgrounds at least partially explain the diverse analogies and comparative reasonings conducted in the field.Footnote ¹⁹ Arbitral practice about the most-favoured-nation clause seems to confirm this influence.Footnote ²⁰ At the systemic level, those diverse backgrounds generate diverging epistemic forces, which greatly contribute to the ratione materiae hybridity of the regime.

That being said, one should not conclude that scientific backgrounds govern ipso facto reasonings. There are many reasons for not drawing such a conclusion.

First of all, asserting the opposite basically may lead one to deny the ability of arbitrators to take some distance from their own background and to focus, as they shall do, on the factual and legal specifics of the cases they are called upon to decide.Footnote ²¹ In relation to this, such a radical view tends to negate the benefit of the collegiality that characterises most arbitral tribunals.Footnote ²² Indeed, according to this view, there is simply no room for an open-minded discussion and argumentation within the tribunal. There exists no possibility that the dynamics at play between the arbitrators, in the frame of the factual and legal specifics of cases, lead them to broaden their epistemic horizon.

Secondly, it is also of great import not to oversimplify the epistemic landscape and legal practice in our field. Indeed, diversity has not only a collective dimension but also an individual one. A number of stakeholders in international investment law and arbitration have, themselves, a diverse scientific background, rooted in different legal traditions, orders, or disciplines. This is simply the result of the inter-disciplinary and transnational education and experience acquired by those stakeholders.Footnote ²³

Thirdly, it is worth realising that comparative reasoning is not only a matter of scientific background and knowledge, but that it is also one of interests and capacities. The role that each of the international investment law and arbitration professionals plays in the system impacts (or in any case should impact) on the extent to which she builds her work on her background. Acting as an arbitrator in proceedings is a different exercise than writing an article as a scholar. Also, obviously, acting as a counsel and the interests that one is called upon to defend in that capacity inform if and how one relies on one’s own background. Likewise, it indicates the type of comparative reasoning that one conducts.

All these considerations should be taken into account when considering the ratione personae hybridity that no doubt characterises and impacts on the regime, notably in the context of its legal indeterminacy.

3.2.3 Legal Indeterminacy

Legal indeterminacy has been typical of IIAs’ provisions since the adoption of the first IIA between Germany and Pakistan in 1959.Footnote ²⁴

More precisely, among all forms of indeterminacy,Footnote ²⁵ they have been characterised by the indeterminacy of language as notably theorised by Hart.Footnote ²⁶ He made notably a distinction between ‘easy cases’ and ‘hard cases’, in relation respectively to the ‘core’ and the ‘penumbra’ of legal rules. In easy cases, which involve the core of legal rules, their application does not raise any specific difficulty as their meaning appears to be relatively clear in relation to the facts. On the contrary, there is no such linguistic clarity in hard cases that pertain to the penumbra of legal rules. In those hard cases, several plausible interpretations exist, the issue – discussed in Section 3.4 – being then to select one among them. Of course, legal rules and their application can hardly be divided into two clear-cut categories; yet they constitute no doubt the two extreme sides of a sliding scale along which the degree of linguistic indeterminacy varies.Footnote ²⁷ IIA provisions have traditionally been characterised by a pretty high degree of indeterminacy. Well-known examples are the fair and equitable treatment (FET) and indirect expropriation. What do fairness and equity mean and cover as regards the former?Footnote ²⁸ What are the criteria and circumstances to be taken into account to determine the occurrence of an indirect expropriation?Footnote ²⁹ These are key questions and challenges that academics and, most importantly, counsels and arbitrators have been facing. To deal with this indeterminacy, notably when international law rules of interpretation fail to deliver a clear meaning, they often rely on paradigms, legal systems, or specific rules that they deem relevant, be it for functional or strategic reasons. This is well illustrated by the practice of arbitral tribunals concerning expropriation. They have relied on various legal systems, rules, and principles in the process of applying that provision and appraising the existence of indirect expropriations.Footnote ³⁰ Reference has been made in particular to customary international law in relation to the police power doctrine,Footnote ³¹ or to the European Court of Human Rights case law in relation to the proportionality doctrine.Footnote ³²

Of course, drafting has evolved in the IIAs that have been adopted since the 2000s. Treaty provisions in those agreements are often more detailed than they used to be in older ones. Criteria to be taken into account to identify instances of indirect expropriation are included in some treaties,Footnote ³³ while a distinction between expropriatory measures and regulatory measures is made in many of those newly adopted treaties.Footnote ³⁴ Likewise, recent treaty practice appears to be much more specific as regards the content of the FET, be it by listing the components of that standard,Footnote ³⁵ by attaching it to the customary law minimum standard of treatment,Footnote ³⁶ or by providing information about its content. For instance, with regard to legitimate expectations, which is strongly connected to domestic administrative law,Footnote ³⁷ some treaties specify that expectations can only originate from specific representations or commitments.Footnote ³⁸

This trend in treaty practice will no doubt limit the need to rely on analogies and comparative reasoning in the future. That being said, one should remember that the vast majority of the treaties that are the object of current disputes before tribunals form part of the old generation characterised by legal indeterminacy. More fundamentally, that old generation of IIAs is still massively predominant among the treaties currently in force, the new generation constituting only a minority. As a result, comparativism will very likely remain paramount in the reasoning of arbitrators and tribunals in the years to come. It is then very much needed to address the issues that comparativism raises in international investment law and arbitration. Before doing precisely this, it is first necessary to introduce the materials that arbitrators and tribunals rely on when conducting comparative reasonings.

3.3 The Materials of Comparative Reasoning

The materials of comparative reasoning are manifold. To address them and for didactic purposes, a distinction can be made between two types of materials, which are here referred to as forming part of systemic comparative reasoning and specific comparative reasoning.Footnote ³⁹ Each is discussed in turn, the focus being put on the former as, in addition to its intrinsic value, it greatly influences the latter.

3.3.1 Systemic Comparative Reasoning

This type of comparative reasoning consists in the comparison of the international investment law and arbitration regime with other legal systems and paradigms. While this comparison most of the time leads arbitrators and scholars to focus on and favour one of them, they sometimes adopt a pluralistic approach as they consider the regime as a hybrid system. As a result, they rely on various legal systems and paradigms that are seen as being each relevant for different aspects of international investment law and arbitration.Footnote ⁴⁰ Whatever the approach used by those stakeholders, the choice of either of those systems and paradigms is dictated by the analogy that they establish between the situation and problems that arise in international investment law and arbitration and those that arise in those other systems and under those paradigms. This is well illustrated by those who make a comparison between, on the one hand, the foreign investor–host State relationship and, on the other hand, the relation between private persons and the executive.Footnote ⁴¹ Sometimes, this is the analogy in terms of legal structure and substance that drives comparative reasoning, as is illustrated by those who draw an analogy between international investment law and arbitration and international human rights law.Footnote ⁴²

Those legal systems and paradigms that are relied upon in international investment law and arbitration are well-known, in particular the public-private law paradigms. They have already been studied in great detail in the literature.Footnote ⁴³ While they are well-known, one should yet be cautious when looking at the systemic and paradigmatic landscape to ensure that one catches all its nuances. This matters as oversimplifying that landscape deprives us from the possibility of getting a sound understanding of systemic comparative reasoning and, most importantly, can lead in practice to making wrong analogies. Two main reasons call for such a cautiousness.

From a methodological point of view, first, the landscape appears to be actually messy. This is mainly due to the fact that there are different ways, in particular in the literature, to map the systemic and paradigmatic landscape. Notably, to develop their typology, some focus on the ‘nature’ of the body of law, that is, public or private, or on, so to speak, the ‘localisation’ of the legal order, that is, domestic, international, transnational. For instance, some authors who rely on or discuss the public-private divide put under the paradigmatic umbrella of the ‘public’ both domestic public law and public international law.Footnote ⁴⁴ On the contrary, others make a distinction between them.Footnote ⁴⁵ Likewise, classifications are based, explicitly or implicitly and alternatively or in combination, on the nature of investment arbitration and on the functions that it performs.Footnote ⁴⁶

The second reason that calls for cautiousness consists in the fact that those systems and paradigms display, themselves, diversity. This is well illustrated by the public international law paradigm. It encompasses analogies with general public international law,Footnote ⁴⁷ international human rights law,Footnote ⁴⁸ or WTO law.Footnote ⁴⁹ This diversity matters as the analogy with each of them can lead to different outcomes in international investment law and arbitration. This is well illustrated by the debate about the derivative or direct nature of investors rights by analogy with the traditional model of diplomatic protection and human rights, respectively,Footnote ⁵⁰ which has an impact on concrete issues such as the characterisation of IIAs breaches as countermeasures.Footnote ⁵¹

Irrespective of the need to approach the matter cautiously, it is worth insisting that systemic comparative reasoning is not a mere academic exercise. The choice of either of those systems and paradigms has substantive practical consequences. A very telling example is provided by the issue of state consent to arbitration. The way it is construed by arbitrators depends largely on the paradigm they rely on. And this greatly contributes to explain the diverse and conflicting views they adopt on specific legal issues, such as the status and nature of pre-conditions to arbitration, or the application of the most-favoured-nation clause to IIAs’ dispute settlement provisions.Footnote ⁵²

3.3.2 Specific Comparative Reasoning

While systemic comparative reasoning pertains to comparisons with other legal systems and paradigms considered as a whole, specific comparative reasoning consists in the comparison with specific principles, rules, judicial decisions, and practices forming part of such other legal systems. As it appears, the latter is closely connected to the systemic understanding that international investment law and arbitration’s stakeholders have of the regime. For instance, those who make an analogy between international investment law and international human rights law will have a strong tendency to turn to the case law of human rights courts.

Specific comparative reasoning is seen here in the context of the interpretation of IIAs’ provisions, which constitutes the focus of the chapter. In that context and as discussed in Section 3.4, the materials of that reasoning can be used for various purposes that need to be distinguished as they raise different issues. At this stage, it suffices to say that they are mainly called upon to play a role in evidencing the existence and/or the content of international law rules. This is true notably when materials, notably past judicial decisions, are relied on directly in the process of determining the content of those IIAs’ provisions. But this holds true also in those situations where materials are relied upon in relation to other sources, which are themselves used in the interpretation of IIAs’ provisions. For instance, domestic rules and principles are used to determine GPL but also as state practice for the identification of customary international law.

Before that, it is worth noting that arbitral tribunals often do not specify or justify how and why they can rely on those materials and sources. Yet, most of the time, it suffices to refer to the gateways that public international law and international arbitration offer to make this possible. Article 31(3)(c) of the 1969 Vienna Convention on the Law of Treaties is one of them as it provides that, when interpreting a treaty, ‘there shall be taken into account … any relevant rules of international law which is applicable in the relations between the parties’.Footnote ⁵³ Referring to judicial decisions as a subsidiary means for determining rules of law – as coined in Article 38 of the International Court of Justice Statute – is also relevant in this respect.Footnote ⁵⁴ Last but not least, the applicable law chosen by the disputing parties – when international law is part of it – or the law applicable pursuant to Article 42(1) of the ICSID Convention are also of interest to justify the reliance on those materials and sources.Footnote ⁵⁵

3.4 The Issues Raised by Comparative Reasoning

The issues raised by comparative reasoning in international investment law and arbitration can now be addressed in light of the above, with a focus on investor-state arbitration. At the outset, it is worth stressing that some of the issues faced by this judicial forum are actually faced by all judicial fora. Those issues are mainly methodological in nature. They pertain to the determination of the terms of the comparison, to their similitude (or lack thereof), and to the comparison stricto sensu. Although they are intertwined with those methodological issues, additional issues are proper to investor-state arbitration, as they pertain to the application of IIAs’ provisions. They arise notably in relation to the canons of treaty interpretation and to the theory of sources. To fully grasp those issues, the discussion is conducted here from a twofold perspective – that is, legality and legitimacy, starting with the former.

3.4.1 Legality Perspective

As explained above, the theory of sources, and what it teaches us about the determination of the rules of international law, is highly relevant for the purpose of this chapter as all international law sources play a role in the interpretation of IIAs’ provisions. Instances where rules emanating from those sources have been relied on by tribunals in that interpretative process are manifold. Customary international law has been used, for example, in the course of the interpretation of expropriation provisions in applicable IIAs,Footnote ⁵⁶ or in the context of the interpretation of fair and equitable treatment provisions in relation to the minimum standard of treatment.Footnote ⁵⁷ GPL have been relied on, for instance, in that latter context in relation to legitimate expectations.Footnote ⁵⁸ As for the case-law, it has been used – often implicitly – as a subsidiary source in the context of the interpretation of many provisions, such as the umbrella clauseFootnote ⁵⁹ or the most-favoured-nation clause.Footnote ⁶⁰ Relying on those sources requires to make comparisons between state practices, domestic rules and principles, and past ‘judicial’ decisions, respectively. Let us appraise the practice of tribunals thereon, focusing successively on the comparisons between judicial decisions and between domestic rules/principles.

Among the judicial decisions rendered by international courts and tribunals, past arbitral awards or decisions are by far the main type of ‘judicial’ decisions relied on by tribunals in investor-state arbitration. Depending on the case at hand, tribunals rely on one precedent, on a few of them, or on jurisprudence constante, which are made of series of precedents.Footnote ⁶¹ In all those situations, the issue of similarity arises. More precisely, the issue is twofold. First of all, it is worth flagging that similarity does not amount to identity. This begs the question of the degree of similarity or, to put it differently, the question of the conditions under which similarity is deemed to be sufficient. Secondly, it matters to realise that similarity should characterise two sets of relations. Past awards/decisions should first display similarity between themselves. Also, they should be (sufficiently) similar to the factual and legal specifics of the case at hand, in particular to the IIA provision being interpreted.

A review of arbitral practice shows that tribunals hardly ever enquire into similarity in practice. This holds true as regards the similarity that should characterise the two sets of relation mentioned above. Ipso facto, this also applies to the degree of similarity. Such a trend is obviously an issue in methodological terms. But, more fundamentally, this is an issue inasmuch as this may lead to situations where the interpretation that derives from relying on precedents conflicts with the intent of treaty parties, by failing to respect the textual, the teleological, or the contextual specifics of the treaty at hand.Footnote ⁶²

Turning to the discussion of arbitral practice pertaining to the reliance on domestic rules and principles, attention should first be drawn to selectivity. Tribunals most of the time refer to a very limited number of domestic legal orders and rules thereof in the process of interpreting IIAs’ provisions.Footnote ⁶³ Also, they usually hardly enquire into the similarity between those rules and principles. Is it an issue? The lack of discussion about similarity is no doubt one, as this is a conditio sine qua non to testify of their collective substantive significance. As for selectivity, the answer to the question depends actually on the function assigned to relying on those domestic rules and principles. When the intent is to fill a gap by trying to evidence the existence of a GPL, this seems to be an issue indeed. It is so because the theory of sources teaches us that such general principles should be widespread across domestic legal systems and be characterised by representativeness.Footnote ⁶⁴ On the contrary, when the intent of the tribunal is to confirm an interpretation reached on other grounds, it is less of a concern as those domestic rules and principles relied upon do not aim at evidencing such a general principle.Footnote ⁶⁵ Such a reasoning does not run against the theory of sources, which appears to be irrelevant in that context. From a legality point of view, nothing prevents such a use of domestic rules and principles. On the other hand, this appears to be more problematic seen from the standpoint of legitimacy, to which the chapter now turns to fully grasp the issues raised by comparative reasoning in investor-state arbitration.

3.4.2 Legitimacy Perspective

Legitimacy – understood here as the acceptance of a power exercised by an entity – does matter when appraising the use of comparative reasoning in arbitral practice, as it does more generally as regards the existence and functioning of arbitral tribunals.Footnote ⁶⁶ This results from the power that they exercise and that impacts on disputing parties and beyond, in particular on local populations. This power consists primarily in the settlement of the disputes submitted to tribunals. But it also materialises into the law-making function that they are de facto called upon to perform when interpreting vague IIAs’ provisions.Footnote ⁶⁷ Indeed, their legal indeterminacy, discussed in Section 3.2.3, requires from tribunals to make choices as regards the substance that they give to those provisions in light of the facts of cases. To beef up the acceptability of those choices – and more generally of the power they perform – tribunals have to provide arguments in support thereof. As it appears, this de facto law-making function, and interpretation in the context of which this function is formally exercised, boils down to an argumentative practice that is intended to convince the tribunal’s audiences of the soundness of the choices made.Footnote ⁶⁸ Comparative reasoning being one method used by tribunals to exercise this de facto law-making function, the way it is conducted should contribute to convince the tribunals’ audiences.

This is where, in particular, the selectivity of arbitral tribunals as regards the domestic principles or rules that they use can be seen as an issue. Even though such a selectivity cannot be challenged from a legality standpoint when they are relied upon to confirm an interpretation, a ‘pick and choose’ approach opens a Pandora’s box of criticism from that legitimacy point of view. Critics denounce notably the legal hegemony and the cultural biases across the investment law and arbitration community that this selectivity reflects.Footnote ⁶⁹ All this undermines the acceptability of the choices made by tribunals, the acceptability of awards or decisions, and, more fundamentally, the acceptability of investor-state arbitration.

Beyond the academic debate among comparativists between the proponents of functionalism and culturalism as regards the significance of cultural specificities,Footnote ⁷⁰ the difficulty in investor-state arbitration is obviously that the audience is diverse.Footnote ⁷¹ Distinctions can be made between disputing parties and a broader audience and between states and investors. Another distinction can be made between states depending on whether they belong to the Global South or the Global North. Local populations and civil society are also seen as constituting an additional audience of arbitral tribunals.Footnote ⁷²

This diversity of the audience brings a diversity of expectations. Its component parts often have diverse and sometimes conflicting expectations of arbitral tribunals and, more generally, of international investment law and arbitration. In relation to the discussion conducted in Section 3.3.1 about systemic comparative reasoning, it appears that those expectations are governed by the respective system or paradigm those component parts of the audience rely on. In light of that context, arbitral tribunals seem to have little chance, when conducting their systemic comparative reasoning, to succeed in convincing all of them that they made the right choice in their interpretation of vague IIAs’ provisions.

3.5 Conclusion

The discussion conducted in this chapter flags up methodological flaws that exist in the use of comparative reasoning by arbitral tribunals in the process of interpreting vague IIAs’ provisions. If these flaws cannot all be criticised from a legality point of view, they have yet the potential, from a legitimacy standpoint, to undermine the acceptability of their awards and, beyond, of investor-state arbitration as a whole. From that latter point of view, it was also argued that the argumentative strength of comparative reasoning faces limits due to the diversity of the audience of arbitral tribunals.

Those findings sound pretty negative. But there are actually reasons to conclude on a positive note. First, the way tribunals conduct comparative reasoning can improve. In particular, they can pay greater attention to the issue of similarity and be less selective. More fundamentally, there are reasons for being optimistic because of the current evolution of the regime. This is due to the fact that, incrementally, international investment law and arbitration is developing new traits that – in the long run – will make the use of comparative reasoning less pressing and, in any case, will certainly rationalise the way it is used.

First of all, as touched upon in Section 3.2.3 in relation to legal indeterminacy, recent treaty practice shows that IIAs’ provisions are much more detailed than they used to be in the agreements adopted in the past.Footnote ⁷³ This means that relying on comparative reasoning to interpret those provisions will not be necessary in the future, or in any case less necessary. Secondly – and more importantly– one can conclude on a positive note because of the identity that the regime is progressively acquiring. Why and how? In a nutshell, because it increasingly enables people to be informed and to express their opinions and arguments. This clearly appears in the various mechanisms and fora that have recently been set up to allow various stakeholders to formally contribute to law-making and to dispute settlement,Footnote ⁷⁴ in particular at ICSID.Footnote ⁷⁵ As illustrated by the reform of investor-state arbitration, this contribution – and the exchange of views it permits – allow the regime to make progress in building its own identity. Even if one is less optimistic, one may consider at least that the regime is being equipped to build that identity.

In the end, one should not forget that international investment law and arbitration, as we know it, is still a pretty young legal regime. Identity being certainly a result more than a given, it is unsurprising that the regime is still building a proper one. The procedural mechanisms and existing fora help in this process. They speed up and streamline that process, which otherwise would certainly have been more chaotic and slower. That being said, one should realise that getting an identity does not amount to the disappearance of hybridity; international investment law and arbitration will no doubt remain hybrid to a certain degree. Is that a problem and could it be any different? Certainly not, as hybridity appears to be inherent to our legal systems.Footnote ⁷⁶ This is the common fate that they all face, especially as a result of globalisation and of the ever-growing interaction between cultures and legal systems.Footnote ⁷⁷

Footnotes

¹ K Zweigert and H Kötz, Introduction to Comparative Law (T Weir tr, 3rd edn, Oxford University Press 1998) 2. Comparativism is referred to in this chapter as a methodology, not as a legal field nor a discipline. The key tenets of that methodology are stressed across the chapter. For a discussion of comparativism as a legal field and a discipline see e.g. T Lundmark, Charting the Divide Between Common and Civil Law (Oxford University Press 2012) (chapter 1: ‘The Discipline of Comparative Law’). In this chapter, ‘comparativism’ is used interchangeably with ‘comparative reasoning’.

² V Vadi, Analogies in International Investment Law and Arbitration (Cambridge University Press 2016) 249, referring to M Adams and J Bomhoff, ‘Comparing Law: Practice and Theory’ in M Adams and J Bomhoff (eds), Practice and Theory in Comparative Law (Cambridge University Press 2013) 6.

³ Likewise, Sabino Cassese considers that comparativism brings a ‘transnational’ legal discourse. See S Cassese, ‘Beyond Legal Comparison’ [2012] Annuario di Diritto Comparato e di studi legislativi 387, 388.

⁴ On general principles of law, see ILC, ‘Draft Conclusions on General Principles of Law, with Commentaries’ (24 April–2 June and 3 July–4 August 2023) UN Doc A/78/10, 13, Conclusion 5 (2) (hereinafter Draft Conclusions on General Principles).

⁵ On the sources of rights and obligations in international investment law and arbitration, see e.g. T Gazzini and E de Brabandere, International Investment Law – The Sources of Rights and Obligations (Brill 2012).

⁶ On the customary law minimum standard of treatment, see e.g. P Dumberry, ‘The “Minimum Standard of Treatment” in International Investment Law: The Story of the Emergence, the Decline and the Recent Resurrection of a Concept’ in K Polackova van der Ploeg, L Pasquet, and L Castellanos-Jankiewicz (eds), International Law and Time – Narratives and Techniques (Springer 2022) 381.

⁷ On the lex mercatoria, see e.g. E Gaillard, ‘Thirty Years of Lex Mercatoria: Towards the Selective Application of Transnational Rules’ (1995) 10 ICSID Review – Foreign Investment Law Journal 208.

⁸ See e.g. P Mayer, ‘Le mythe de l’ordre juridique de base (ou Grundlegung)’ in P Fouchard, P Kahn, and A Lyon-Caen (eds), Le droit des relations économiques internationales – Etudes offertes à Berthold Goldman (Litec 1982) 199; P Weil, ‘Problèmes relatifs aux contrats passés entre un Etat et un particulier’ (1969) 128 RdC 94.

⁹ In this respect, it is noteworthy that European policymakers prepared their BIT models relying on the 1967 OECD Draft Convention on the Protection of Foreign Property, following thereby the OECD Council, which had expressed the view that ‘the Draft Convention will be a useful document in the preparation of agreements on the protection of foreign property’. OECD, ‘Resolution of the Council on the Draft Convention on the Protection of Foreign Property’ (2025) OECD/LEGAL/0084 <https://legalinstruments.oecd.org/public/doc/242/242.en.pdf> (last accessed 1 June 2025).

¹⁰ In addition to the US BIT Model mentioned below, see, for instance, the 2015 India Model, the 2017 Colombia Model, and the 2019 Morocco Model, available on the website of the UNCTAD Investment Policy Hub <https://investmentpolicy.unctad.org/international-investment-agreements/model-agreements> (last accessed 1 June 2025). For analyses of treaty models, see C Brown, Commentaries on Selected Model Investment Treaties (Oxford University Press 2013).

¹¹ Treaty Between the Government of the United States of America and the Government of […] concerning the Encouragement and Reciprocal Protection of Investment (2004) <https://investmentpolicy.unctad.org/international-investment-agreements/treaty-files/2872/download> (last accessed 1 June 2025).

¹² See i.e. US Supreme Court, Penn Central Transportation Co v New York City (1978) 438 US 104. As evidenced by Annex 6 of the US BIT Model, the case-law of the US Supreme Court has been very influential as regards the list of factors to be taken into account to determine whether a measure constitutes an indirect expropriation. The notion of ‘distinct, reasonable investment-backed expectations’ is key in this respect. On this notion, see e.g. JA Kupiec, ‘Returning to Principles of “Fairness and Justice”: the Role of Investment-Backed Expectations in Total Regulatory Taking Claims’ (2008) 43 Boston College Law Review 865.

¹³ See e.g. Agreement Between the Slovak Republic and the Islamic Republic of Iran for the Promotion and Reciprocal Protection of Investments (signed 19 January 2016; entered into force 30 August 2017) <https://investmentpolicy.unctad.org/international-investment-agreements/treaty-files/3601/download> (last accessed 1 June 2025).

¹⁴ ICSID has led that process in the context of the revision of its arbitration rules, notably by incorporating amicus curiae in the 2006 version of the Arbitration Rules (Rule 37) <https://icsid.worldbank.org/sites/default/files/ICSID%20Convention%20English.pdf> (last accessed 1 June 2025). This mechanism is provided in Rule 66 of the 2022 version of the Rules <https://icsid.worldbank.org/rules-regulations/convention/arbitration-rules/chapter-x-publication%2C-access-to-proceedings-and-non-disputing-party-submissions> (last accessed 1 June 2025). On transparency in that latest version of the Rules, see e.g. GJ Shaw, ‘The 2022 ICSID Rules: a Leap Toward Greater Transparency in ICSID Arbitration’ (2023) 38 ICSID Review – Foreign Investment Law Journal 54.

¹⁵ On this phenomenon, see e.g. J Alvarez, ‘The Return of the State’ (2011) 20 Minnesota Journal of International Law 268.

¹⁶ This approach is promoted in particular by Brazil, see e.g. Acuerdo de Cooperacion y de Facilitation de las Inversiones Entre la Republica Federativa del Brazil y los Estados Unidos Mexicanos (signed 26 May 2015; entered into force 7 October 2018) <https://investmentpolicy.unctad.org/international-investment-agreements/treaty-files/4718/download> (last accessed 1 June 2025). On this approach, see e.g. R Polanco, The Return of the Home State to Investor-State Disputes – Bringing Back Diplomatic Protection? (Cambridge University Press 2019).

¹⁷ On this debate, see e.g. M Paparinskis, ‘Investment Treaty Arbitration and the (New) Law of State Responsibility’ (2013) 24 EJIL 617 and the debate with Anastasios Gourgourinis on the matter. A Gourgourinis, ‘The Nature of Investor’s Rights under Investment Treaties: A Rejoinder to Martins Paparinskis’ (EJIL:Talk!, 31 October 2013) <www.ejiltalk.org/the-nature-of-investors-rights-under-investment-treaties-a-rejoinder-to-martins-paparinskis/> (last accessed 1 June 2025).

¹⁸ On this issue, see e.g. A Bianchi, ‘Epistemic Communities in International Arbitration’ in F Ortino and T Schultz (eds), Oxford Handbook of International Arbitration (Oxford University Press 2017) 569.

¹⁹ In that sense, see also A Roberts, ‘Clash of Paradigms: Actors and Analogies Shaping the Investment Treaty System’ (2013) 45 AJIL 45, 48.

²⁰ This is well illustrated by the number of dissenting opinions written on the matter. See e.g. Y Radi, Rules and Practices of International Investment Law and Arbitration (Cambridge University Press 2020) 131.

²¹ About the importance of being open-minded in arbitration, see e.g. Global Arbitration Review, ‘Q&A with Professor Pierre Lalive’ <https://cdn.arbitration-icca.org/s3fs-public/document/media_document/media01231910475880008_10_14_gar-pla_interview.pdf> (last accessed 1 June 2025).

²² On the matter, see e.g. CA Rogers, ‘Reconceptualizing the Party-Appointed Arbitrator and the Meaning of Impartiality’ (2023) 64 HarvILJ 137, 165–67.

²³ On this phenomenon, see e.g. E Darian-Smith, ‘Transnational Legal Education’ in P Zumbansen (ed), The Oxford Handbook of Transnational Law (Oxford University Press 2021) 1153.

²⁴ Treaty between the Federal Republic of Germany and Pakistan for the Promotion and Protection of Investments (signed 25 November 1959; entered into force 28 April 1962) <https://investmentpolicy.unctad.org/international-investment-agreements/treaty-files/1387/download> (last accessed 1 June 2025).

²⁵ For a review and an analysis of those forms, see e.g. CA Miles, ‘Indeterminacy’ in J d’Aspremont and S Singh (eds), Concepts for International Law – Contributions to Disciplinary Thought (Edward Elgar 2019) 447.

²⁶ See i.e. HLA Hart, ‘Positivism and the Separation of Law and Morals’ (1957–58) HLR 593, 606–15; HLA Hart, The Concept of Law (3rd edn, Clarendon 2012) 160–61.

²⁷ In that sense, see i.e. N MacCormick, Legal Reasoning and Legal Theory (Clarendon 1978) 234–35.

²⁸ See e.g. G Ünüvar, ‘The Vague Meaning of the Fair and Equitable Treatment Principle in Investment Arbitration and New Generation Clarifications’ in AL Kjaer (ed), Language and Legal Interpretation in International Law (Oxford University Press 2022) 271.

²⁹ See e.g. Radi (n 20) 164–74.

³⁰ For a critical account, see e.g. J Calamita, ‘The Principle of Proportionality and the Problem of Indeterminacy in International Investment Treaties’ [2014] Yearbook of International Investment Law and Policy 157.

³¹ See e.g. Philip Morris Brands SARL, Philip Morris Products SA and Abal Hermanos SA v Oriental Republic of Uruguay (Philip Morris v Uruguay) (Award of 8 July 2016) ICSID Case No ARB/10/7 [290–301].

³² See e.g. Tecnicas Medioambientales Tecmed SA v The United Mexican States (Award of 29 May 2003) ICSID Case No ARB(AF)/00/2 [116].

³³ See supra (Footnote n 11) and (Footnote n 12).

³⁴ Here again, this evolution is based on the approach initiated by the US in its 2004 BIT model (Annex B) (Footnote n 11). It is worth noting that, while making a similar distinction, some treaties depart from this approach by excluding that regulatory measures may constitute expropriatory measures in some rare circumstances, see e.g. Treaty Between the Republic of Belarus and the Republic of India on Investments (signed 24 September 2018; entered into force 5 March 2020) (art 5.5) <https://investmentpolicy.unctad.org/international-investment-agreements/treaty-files/5724/download> (last accessed 1 June 2025).

³⁵ See e.g. Agreement Between the Government of Hungary and the Government of the Republic of Cabo Verde for the Promotion and Reciprocal Protection of Investments (signed 28 March 2019; entered into force 2 May 2020) (art 2 Promotion and Protection of Investments) <https://investmentpolicy.unctad.org/international-investment-agreements/treaty-files/5916/download> (last accessed 1 June 2025).

³⁶ See e.g. Agreement Between Canada and the Government of the Republic of Moldova for the Promotion and Protection of Investments (signed 12 June 2018; entered into force 2 May 2020) <https://investmentpolicy.unctad.org/international-investment-agreements/treaty-files/5806/download> (last accessed 1 June 2025).

³⁷ It is noteworthy that most arbitral tribunals have failed to justify the reliance on that notion. On this issue, see e.g. G Potestà, ‘Legitimate Expectations in Investment Treaty Law: Understanding the Roots and the Limits of a Controversial Concept’ (2013) 28 ICSID Review – Foreign Investment Law Journal 88; Radi (Footnote n 20) 88–89. For an exception, see e.g. Total v Argentina in which the Tribunal expressed the view that ‘a comparative analysis of the protection of legitimate expectations in domestic jurisdictions [was] justified […]’. Total SA v Argentine Republic (Decision on Liability of 27 December 2010) ICSID Case No ARB/04/1 [128].

³⁸ See e.g. Comprehensive Economic and Trade Agreement (CETA) between Canada, of the one part, and the European Union and its Member States, of the other part (signed 30 October 2016) (art 8.10.4) <https://investmentpolicy.unctad.org/international-investment-agreements/treaty-files/3593/download> (last accessed 1 June 2025).

³⁹ For mutatis mutandis similar distinctions, see Roberts (Footnote n 19) 46 and Vadi (Footnote n 2) 137 and 175.

⁴⁰ See e.g. J Arato, ‘The Private Law Critique of International Investment Law’ (2019) 113 AJIL 1, 10.

⁴¹ See e.g. the Separate Opinion by Thomas Wälde in International Thunderbird Gaming Corporation v The United Mexican States (Separate Opinion of Thomas Wälde of 1 December 2005 to Award of 26 January 2006) [12–13] <https://www.italaw.com/sites/default/files/case-documents/ita0432.pdf> (last accessed 1 June 2025).

⁴² See e.g. M Paparinskis, The International Minimum Standard of Treatment and Fair and Equitable Treatment (Oxford University Press 2013) 175–80.

⁴³ See e.g. Roberts (Footnote n 19); C Titi, ‘Investment Treaty Arbitration Caught in the Public-Private Law Divide’ (2024) 45 MichJIntlL 441.

⁴⁴ See e.g. J Alvarez, ‘Is Investor-State Arbitration “Public”’ (2016) 7 JIDS 534.

⁴⁵ See e.g. Roberts (Footnote n 19) 63–64.

⁴⁶ See Titi (Footnote n 43) 449–50.

⁴⁷ This approach is well summarised in CJ Tams, S Schill and R Hofmann ‘Radiating Effects: The Gentle Impact of International Investment Law on General International Law’ in CJ Tams, S Schill, and R Hofmann (eds), International Investment Law and General International Law – Radiating Effects (Edward Elgar 2023) 2, 13–16.

⁴⁸ See e.g. Paparinskis (Footnote n 17).

⁴⁹ See e.g. J Kurtz, The WTO and International Investment Law: Converging Systems (Cambridge University Press 2016).

⁵⁰ See Section 3.2.2 on ratione personae hybridity, in particular (Footnote n 19).

⁵¹ See e.g. Archer Daniels Midland Company and Tate & Lyle Ingredients Americas, Inc v United Mexican States (Award of 21 November 2007) ICSID Case No ARB(AF)/04/05 [110-80].

⁵² For views grounded in public international law, see e.g. the Concurring and Dissenting Opinion of Brigitte Stern in Impregilo SpA v Argentine Republic (Concurring and Dissenting Opinion of Brigitte Stern to Award of 21 June 2011) ICSID Case No ARB/07/17 [53] as well as the Dissenting Opinion of Laurence Boisson de Chazournes in Garanti Koza LLP and Turkmenistan (Dissenting Opinion of Laurence Boisson de Chazournes to the Decision on the Objection to Jurisdiction for Lack of Consent of 3 July 2013) ICSID Case No ARB/11/20 [5–7].

⁵³ 1969 Vienna Convention on the Law of Treaties (adopted 23 May 1969, entered into force 27 January 1980) 1155 UNTS 331.

⁵⁴ 1945 Statute of the International Court of Justice (adopted 26 June 1945, entered into force 24 October 1945) 33 UNTS 993.

⁵⁵ Art 42(1) provides that, in case of absence of agreements between the parties, the tribunal shall apply the law of the Contracting State party to the dispute and such rules of international law as may be applicable; Convention on the Settlement of Investment Disputes between States and Nationals of Other States (ICSID Convention) (adopted 18 March 1965, entered into force 14 October 1966) 575 UNTS 159.

⁵⁶ See e.g. Philip Morris v Uruguay (Footnote n 31) [289–90].

⁵⁷ On the relation between both, see e.g. Paparinskis (Footnote n 42).

⁵⁸ See e.g. Gold Reserve Inc and Bolivarian Republic of Venezuela (Award of 22 September 2014) ICSID Case No ARB(AF)/09/1 [576].

⁵⁹ See e.g. Bureau Veritas, Inspection, Valuation, Assessment and Control, BIVAC BV v The Republic of Paraguay (Decision of the Tribunal on Objections to Jurisdiction of 29 May 2009) ICSID Case No ARB/07/9 [138].

⁶⁰ See e.g. RosInvestCo UK Ltd v The Russian Federation (Award on Jurisdiction of October 2007) SCC Case V 079/2005 [49].

⁶¹ On the debate among arbitrators about whether precedents should be followed despite the absence of stare decisis in international (investment) law see e.g. Burlington Resources Inc v Republic of Ecuador (Decision on Liability of 14 December 2012) ICSID Case No ARB/08/5 [187]. As regards the absence of stare decisis in international investment law, see i.e. ICSID Convention (art 53) (Footnote n 55).

⁶² On the risk that relying on precedent may lead to disregard the relevant texts and the applicable law see e.g. G Guillaume, ‘The Use of Precedent by International Judges and Arbitrators’ (2011) 2 JIDS 5, 23.

⁶³ On this issue see J Ellis, ‘General Principles and Comparative Law’ (2011) 22 EJIL 949, 955–58.

⁶⁴ See i.e. ILC, ‘Report of the International Law Commission, Seventy-fourth Session’ (24 April–2 June and 3 July–4 August 2023) UN Doc A/78/10 ‘Text of the draft conclusions on general principles of law adopted by the Commission on first reading’ (Conclusion 5.2). For a critical approach to representativeness, see e.g. Ellis (Footnote n 63) 955–58.

⁶⁵ In that sense, see e.g. D Peat, ‘International Investment Law and the Public Law Analogy: The Fallacies of the General Principles Method’ (2018) 9 JIDS 654, 675–76.

⁶⁶ See e.g. N Grossman, HG Cohen, A Follesdal, and G Ulfstein (eds), Legitimacy and International Courts (Cambridge University Press 2018).

⁶⁷ See e.g. SW Schill, ‘System-Building in Investment Treaty Arbitration and Lawmaking’ (2011) 12 German Law Journal 1083.

⁶⁸ In that sense, see e.g. I Venzke, ‘The Practice of Interpretation in International Law: Strategies of Critique’ in J Dunoff and MA Pollack (eds), International Legal Theory: Foundations and Frontiers (Cambridge University Press 2022) 305. See also CW Tindale, The Philosophy of Argument and Audience Reception (Cambridge University Press 2015).

⁶⁹ See e.g. Vadi (Footnote n 2) 247. In this respect, it is worth noting disagreements in legal scholarship about the representativeness of Western legal orders, both civil and common law ones. On the one hand, some argue that they have spread from their European roots to many other countries across all the continents, be it because of colonialism or legal reforms. On the other hand, other argue that Western ideas of law are not any longer accepted as a primary yardstick. In support of the former approach, see e.g. SW Schill, ‘International Investment Law and Comparative Public Law – an Introduction’ in SW Schill (ed), International Investment Law and Comparative Public Law (Oxford University Press 2010) 29; in support of the latter, see e.g. J Husa, ‘Research Designs of Comparative Law – Methodology or Heuristics?’ in M Adams and D Heirbaut (eds), The Method and Culture of Comparative Law (Hart 2014) 64, cited in Vadi (Footnote n 2) 247.

⁷⁰ Functionalists consider that all societies are faced with the same challenges. In the view of functionalists then, all domestic laws address those same challenges, their rules and concepts being compared because of the analogous function that they perform. On the contrary, the proponents of culturalism believe that societies are confronted with diverse challenges and that domestic law reflects this diversity. Accordingly, they consider that comparativism should take into account that societal and legal diversity. On this issue, see e.g. JC Reitz, ‘How to Do Comparative Law (1998) 46 AJCL 617, 626. See also Vadi (Footnote n 2) 19–34.

⁷¹ This audience can of course vary from one case to the other, depending notably on the subject matter of the disputes. On those issues, see e.g. JA Maupin, ‘Differentiating Among International Investment Disputes’ in Z Douglas, J Pauwelyn, and JE Vinuales (eds), The Foundations of International Investment Law: Bringing Theory into Practice (Oxford University Press 2014) 466.

⁷² On the rise of civil society in investor-state arbitration, see e.g. N Bernasconi, MD Brauch, and H Mann, ‘Civil Society and International Investment Arbitration: Tracing the Evolution of Concern’ in T Schultz and F Ortino (eds), The Oxford Handbook of International Arbitration (Oxford University Press 2010) 304.

⁷³ On this process, see e.g. F Ortino, ‘Refining the Content and Role of Investment “Rules” and “Standards”: a New Approach to International Investment Treaty Making’ (2013) ICSID Review – Foreign Investment Law Journal 152.

⁷⁴ See e.g. E Shirlow, ‘Three Manifestations of Transparency in International Investment Law: A Story of Sources, Stakeholders and Structures’ (2017) 8 Gottingen Journal of International Law 73. On the role of civil society outside formal channels, see e.g. J Cavert, ‘Civil Society and Investor-State Dispute Settlement: Assessing the Social Dimensions of Investment Disputes in Latin America’ (2018) 23 New Political Economy 46.

⁷⁵ See supra (Footnote n 12).

⁷⁶ R Banakar, ‘Power, Culture and Method in Comparative Law’ (2009) 5 International Journal of Law in Context 69, cited in Vadi (Footnote n 2) 73.

⁷⁷ Ellis (Footnote n 63) 966.

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