By Naimeh Masumy

Abstract

This article critically examines the multifaceted role of compound interest in investment arbitration, challenging its traditional categorization within the substantive-procedural divide. It explores the practical challenges tribunals face when dealing with legal mechanisms like compound interest, which inherently span both procedural and substantive dimensions. To clarify this complexity, the article introduces the concept of “proceduralization,” showing that the boundary between procedural and substantive norms is often more fluid than typically assumed. The article then delves into the legal foundations of compound interest, analyzing the classification of norms in public international law and the conceptual distinctions between procedural and substantive categories. This discussion is framed through the lenses of conflict of laws and constitutional law, demonstrating how norms like compound interest occupy a dual role that transcends traditional classifications. Key arbitral decisions, particularly Sempra v. Argentina and Autopista v. Venezuela, are highlighted, illustrating how tribunals have recognized compound interest as both a substantive right to ensure “full compensation” for economic losses and a procedural tool to mitigate delayed payments and prevent unjust enrichment by states. The article concludes by advocating for a more nuanced, context-sensitive approach to compound interest in investment arbitration. This approach is essential for ensuring equitable and commercially viable outcomes, allowing arbitrators to navigate investment disputes more effectively. It calls for a broader recognition of the flexible role of compound interest, ensuring that compensation accurately reflects economic losses while maintaining fairness and procedural efficiency.

Introduction

The law of damages highlights a clear divide between substance and procedure, especially with respect to compound interest.[1] Compound interest is not just a technical detail—it plays a key role in determining the true scale of compensation, the credibility of arbitral awards, and the incentives for complying with them.[2] Whether it is seen as a substantive right or procedural matter, the law of damages has significant consequences: it affects who has authority (the tribunal or the enforcing court), which law applies (international law, treaty text, or lex arbitri), and how awards are calculated and enforced consistently.[3]

As JonathanBonnitcha, Malcolm Langford, José Alvarez-Zarate, and Daniel Behn observe, damages in investor–state disputes expose the porous nature of this divide.[4] The issue is not simply quantum; it goes to the foundation of arbitral authority and the allocation of responsibility between international law and arbitral tribunals.[5] The substantive–procedural split in damages emerges most clearly in two dimensions. First, the normative grounds of compensation are substantive: they define the scope of liability and the extent of recovery under the applicable law, whether treaty text or customary international law. The principle of “full reparation,”[6] articulated in Factory at Chorzow (Germ. v. Pol.), compels a responsible state to restore the status quo ante, covering “any financially assessable damage, including loss of profits.”[7] This right is enshrined in Articles 31–38 of the International Law Commission’s (ILC) Articles on State Responsibility and reinforced by expropriation provisions mandating “fair market value.”[8] Authority in this area rests with tribunals applying substantive international law.[9] Therefore, whether pre-award or post-award interest should be compounded is not a matter of discretion for the tribunal, but rather a matter of substantive entitlement.

In contrast, the methodology for calculating compound interest—such  as the optimal rate, method, and issuance date––is typically procedural and falls within the tribunal’s discretion as the factfinder. Key decisions, like the choice of when to start compounding, whether to use a fixed or commercial rate, and whether the cost of borrowing is a suitable method for compounding, are within the tribunal’s procedural authority to evaluate evidence.[10] Thus, compound interest sits between procedure and substance.[11] Tribunals, like in Sempra v. Argentina,[12] treat it as a substantive part of “full reparation,” while others, like in Autopista v. Venezuela,[13] view it as procedural.[14] This classification is important: if interest is considered substantive, only the tribunal can decide it under international law; if it is procedural, domestic courts can adjust or override it at the enforcement stage under the lex arbitri.[15] This ambiguity, discussed in the United Nations Commission on International Trade Law (UNCITRAL) Working Group III deliberations, shows that the substantive–procedural divide is not just theoretical; it also determines the legal authority between international tribunals and national courts.[16]

This article will first examine the inherent tension in classifying compound interest as either a procedural or substantive instrument. It will clarify that the procedural–substantive distinction is grounded in both constitutional and public international law, where factors such as context, function, and public policy objectives are key to determining its classification. Building on this, the article will provide an overview of how public international law views compound interest—emphasizing its essential role in legitimizing its application. The article will argue that compound interest should not be viewed as a rigid concept; that attempts to strictly categorize it as either procedural or substantive mask its flexibility within the legal framework. Likewise, this article will argue that such a narrow view limits its broader application, as it can serve multiple roles, including deterrence, compensation, and commercial fairness in legal remedies. By analyzing recent jurisprudence, this article will showcase the comprehensive approaches tribunals have adopted in treating compound interest as a legal policy, allowing them to account for economic realities, commercial reasonableness, and evolving legal norms. Finally, this article will advocate for a more adaptable approach, offering practical recommendations for arbitral tribunals to navigate the intersections of substantive and procedural law, while maintaining consistency in their decisions.

Part I explores how tribunals approach compound interest, dividing the issue into two subsections: (1) its legal basis, and (2) its application. It situates the divide within legal traditions, highlighting how each creates uncertainty in the treatment of compound interest. Part II examines “proceduralization,” showing how procedural norms can take on quasi-substantive functions and blur the distinction between the two. Part III shifts to arbitral practice, analyzing key cases to illustrate how tribunals alternate between treating compound interest as a substantive entitlement and as a matter of procedural discretion. Part IV evaluates the implications of this dual characterization, arguing that rigid classifications are neither conceptually coherent nor practically effective. The article concludes by proposing a pragmatic framework to guide tribunals in issuing consistent, defensible, and commercially reasonable awards.

1. Between Substance and Procedure: Compound Interest and the Architecture of Reparation in International Arbitration

Classifying compound interest within the broader framework of damages is not just a technical matter. Its classification impacts both arbitral authority and the enforceability of awards. If compound interest is viewed as purely procedural, the tribunal has full discretion to decide whether to grant it and determine the methods––such as the rate, compounding period, and accrual structure––without external influences such as treaty provisions, customary international law, or domestic laws. National courts are then required to enforce the award under frameworks such as the New York Convention, the International Centre for Settlement of Investment Disputes (ICSID) Convention, or relevant investment treaties.[17] However, jurisprudence reveals that tribunals frequently struggle to characterize compound interest and to anchor their reasoning in a coherent body of law.[18] There are two axes of inconsistency that stand out. The first concerns validity: tribunals frequently invoke the principle of “full reparation,” Article 38 of the ILC Articles on State Responsibility, treaty provisions, or domestic law to justify awarding compound interest.[19] When domestic law is invoked, tribunals typically conduct a conflict-of-laws analysis to determine the applicable rule––highlighting the conceptual weakness of the procedural–substantive divide. [20] The second concerns methodology: tribunals diverge on the appropriate rate, the frequency of compounding, and the optimal accrual method. In practice, tribunals tend to draw on prior arbitral awards, commercial practice, or lex mercatoria to justify their choices.[21] Yet, despite the centrality of these determinations to the quantum of damages, tribunals rarely confront the antecedent question of how compound interest should be characterized.[22] Critically, tribunals must strike a careful balance between respecting party autonomy, adhering to the governing arbitration law (lex arbitri), and exercising their discretionary authority to ensure fairness and procedural integrity.[23]

A good example of this inconsistency in the treatment of compound interest, including its validity and methodology, which emerges in arbitral jurisprudence. As the Compañía del Desarrollo de Santa Elena SA v. Republic of Costa Rica tribunal observed, “compound interest reflects the economic reality of financial transactions;” to deny it is to deny the time-value of money.[24] Tribunals, such as the ones inSempra Energy International v. Argentine Republic,[25] and and LG&E International Inc v. Argentine Republic[26] have recognized this contention, while leading commentators, including Borzu Sabahi and Michele Potestà, have argued that without compound interest, investor compensation is systematically inadequate.[27]

However, within the domain of compound interest, substantive principles often collide with procedural discretion, as evidenced in several landmark cases. In Southern Pacific Properties Ltd v. Arab Republic of Egypt,[28] for instance, the tribunal applied Article 42(1) of the Washington Convention, holding that Egyptian domestic law governed interest because “there is no rule of international law that would fix the rate of interest or proscribe the limitations imposed by Egyptian law.”[29] This reliance on domestic law demonstrates that, in the absence of specific international standards, tribunals may apply rules less favorable to claimants than commercial practice would demand. By contrast, in Desert Line Projects LLC v. Republic of Yemen,[30] the tribunal rejected compounding and awarded only simple interest at five percent, framing interest as a discretionary matter and an equitable adjustment rather than a substantive right flowing from full reparation.[31]

Critically, when determining the viability of enforcing compound interest, arbitral tribunals have drawn a nuanced distinction between pre-award and post-award phases.[32] Although no uniform doctrine has crystallized, the prevailing tendency is to regard pre-award compound interest as an indispensable element of the principle of full reparation.[33] In this context, compound interest is treated as a substantive right owed to the injured party. This line of reasoning is exemplified in Vivendi II v. Argentina, where the tribunal awarded six percent compound interest expressly on the basis that only such an approach could secure restitutio in integrum.[34] The same substantive orientation was evident in LG&E v. Argentina and PSEG v. Turkey,[35] both of which emphasized that simple interest would necessarily leave claimants undercompensated.[36] Post-award interest, by contrast, has generally been viewed as a procedural matter aimed at deterrence. In this context, tribunals are granted significant discretion, especially in selecting the applicable interest rate. Some tribunals have opted for risk-free rates, as demonstrated in NextEra v. Spain,[37] where a sovereign bond yield of 0.2% was applied. On the other hand, tribunals in cases such as Tethyan Copper v. Pakistan[38] have chosen commercial benchmarks, such as the London Inter-Bank Offered Rate (LIBOR) plus a margin, compounded quarterly, resulting in a multi-billion-dollar liability.[39]

Tribunals have significant discretion in selecting the most appropriate method for calculating compound interest, with common approaches including: (1) risk-free benchmarks, (2) commercial benchmarks, (3) commercial borrowing costs, and (4) reinvestment/ Weighted Average Cost of Capital (WACC). While risk-free and commercial rates are the most frequently used, tribunals are increasingly opting for methods that better reflect financial realism. Risk-free instruments, such as U.S. Treasury Bills or short-term sovereign bonds, measure only the pure time value of money, excluding speculative or project-specific risks, as discussed below.

1. Risk-Free Benchmarks: Treasury Bills and Sovereign Bonds

Tribunals often adopt a conservative approach when determining compound interest by referencing risk-free instruments, such as U.S. Treasury Bills or short-term sovereign bonds.[40] This method treats interest as a neutral indicator of the time value of money, avoiding the inclusion of speculative or project-specific risks. For example, in Adel A. Hamadi Al Tamimi v. Oman,[41] the tribunal used the ninety-one-day U.S. Treasury Bill rate, compounded quarterly, to calculate post-award interest on costs.[42] This decision highlights how tribunals exercise discretionary judgment to select a benchmark that prioritizes fairness and neutrality, rather than adhering to a rigid formula. However, even risk-free instruments are influenced by the creditworthiness of the issuing state, reflecting that tribunals’ choices are flexible and tailored to the specifics of each case.[43]

2. Commercial Benchmarks: LIBOR and EURIBOR Plus a Margin

In many cases, tribunals use commercial reference rates such as LIBOR or Euro Interbank Offered Rate (EURIBOR), adding a margin to reflect typical borrowing conditions. For instance, in Bahgat v. Egypt,[44] the tribunal awarded interest at “USD 12-month LIBOR + 2%, compounded annually.”[45] This demonstrates that the selection of a benchmark is not merely substantive but also procedural.[46] Tribunals exercise discretion to choose rates that reasonably mirror commercial realities, balance competing submissions, and ensure fairness in the award.[47] The decision to adjust margins and reference rates underscores the role of procedural judgment in determining how interest should accrue over time.

3. Claimant’s Cost of Borrowing

Another approach tribunals may adopt is to base interest on the claimant’s actual or typical borrowing costs. In Tidewater v. Venezuela,[48] the tribunal rejected the respondent’s suggestion to use sovereign bond yields, instead emphasizing that interest represents the cost of borrowing the amount the claimant should have received.[49] By tailoring the award to reflect the claimant’s financing reality, the tribunal exercised its discretion, demonstrating that the calculation of interest is more of a procedural exercise than a purely mechanical one. It involves balancing evidence, economic context, and fairness.

4. Reinvestment Returns and WACC-Based Methodologies

Some tribunals base compound interest on reinvestment potential or the WACC, which reflects the returns the claimant could have earned had they received timely compensation. In Compañía del Desarrollo de Santa Elena v. Costa Rica,[50] the tribunal applied a compounding method linked to short-term U.S. certificates of deposit, carefully calibrating the rate to strike a balance between fairness and realism.[51] This approach, which moderates speculative claims based on WACC, further illustrates that determining interest is a case-specific procedural exercise, shaped by the specific circumstances of each case rather than a rigid, mechanical calculation.[52]

Tribunals’ approach to compound interest reflects its procedural nature. Instead of directly applying rates or methods from investment treaties or domestic court standards, they often rely on fairness, financial realism, and equitable treatment to address gaps in the treaties.[53] This indicates that interest decisions are guided more by the tribunal’s judgment of just compensation than by treaty law.[54] The diversity of methodologies tribunals use to award compound interest highlights the variety of approaches to this issue.[55] Critically, the tribunal must strike a careful balance between respecting party autonomy, adhering to the governing arbitration law (lex arbitri), and exercising its discretion to ensure fairness and procedural integrity.[56] The classification of compound interest as either a substantive or procedural issue significantly influences the determination of applicable law. This distinction affects the discretion available to arbitrators, the weight of party agreements, and the enforceability of awards that include compound interest.[57] When compound interest is classified as a substantive right of investors and host states, it assumes a compensatory role, signifying a financial obligation owed by the defaulting party.[58] In this context, the imposition of compound interest is crucial for adhering to the standards of full reparation, ensuring that the aggrieved party is made whole for their losses. Conversely, if compound interest is regarded as a procedural element within the arbitration framework, its application is justified by the necessity of procedural fairness.[59] In this scenario, the governing law would be informed by pertinent legal standards, affording arbitrators considerable discretion in determining whether this legal mechanism is utilized to maintain the procedural integrity of investment arbitration.

To fully grasp the foundational principles that underpin the characteristics of compound interest as a legal mechanism, often viewed as integral to the damages framework, it is essential to examine its core within the context of public international law, as outlined below.

II. The Legal Characterization of Compound Interest: Exploring Its Origins in the Constitution.

This section places compound interest within the framework of public international law. With vague standards and limited references in international law, its underlying principles are open to interpretation. The absence of clear customary law further complicates matters, leading tribunals to apply compound interest differently. Without clear guidance on simple or compound interest, each tribunal determines “full reparation” on a case-by-case basis, resulting in varied outcomes.[60]

III. Public International Law: The Obscured Yet Needed Ground

Article 38 of the ILC’s Draft Articles on the Responsibility of States for Internationally Wrongful Acts (2001) allows the imposition of interest on compensation to ensure “full reparation,”[61] but does not explicitly mention compound interest.[62] It states that “interest or any principal sum due under this chapter shall be payable, when necessary, to ensure full reparation.”[63] While compound interest is not required, some tribunals have interpreted “full reparation” to include it, especially in commercial and investment arbitration, where it better reflects the time value of money.[64] For example, in LG&E International, Inc. v. Argentine Republic,[65] the tribunal awarded compound interest to fully compensate the investor’s losses.[66] Similarly, in Vivendi Universal S.A. v. Argentine Republic,[67] the tribunal granted compound interest, reasoning that simple interest would not adequately address the claimant’s ongoing economic harm.[68] Tribunals often face the challenge of deciding whether interest should be simple or compound, interpreting “full reparation” on a case-by-case basis.[69] Martin Paparinskis discusses this ambiguity in relation to Article 38 of the ILC, noting that the cautious approach to compound interest arises from varying state practices and the lack of a uniform standard.[70] He argues that while Article 38(1) affirms the payment of interest for full reparation, Article 38(2) does not codify existing practices but establishes a presumption for interest calculation.[71] Paparinskis concludes that interest rates and methods should aim for “full reparation” while allowing flexibility in international disputes.[72]

Paparinskis’s view on flexible interest norms reflects the current state of international investment law, which is marked by ambiguity and varied interpretations.[73] The absence of explicit provisions in Article 38 requires tribunals to look beyond international law.[74] They often refer to multilateral investment treaties and industry standards to guide their decisions.[75] When awarding compound interest, tribunals typically rely on treaties or arbitration agreements, such as Bilateral Investment Treaties (BITs), that explicitly allow compound interest for treaty breaches.[76] In the absence of explicit provisions, tribunals use customary norms or commercial standards to justify compound interest.[77] They aim to ensure that compensation reflects economic realities, guided by equity and good faith. For instance, in Compañía del Desarrollo de Santa Elena, S.A. v. Republic of Costa Rica,[78] the tribunal awarded compound interest, reasoning that it was essential to achieve “full reparation” for economic losses resulting from delayed payments and lost opportunity costs.[79] Similarly, in Wena Hotels Limited v. Arab Republic of Egypt,[80] the tribunal justified the use of compound interest by citing standard financial practices in the claimant’s industry, where compounded returns were customary, ensuring the award met the claimant’s reasonable expectations.[81] By leveraging treaty frameworks, industry practices, and foundational legal principles, tribunals adopt a context-sensitive approach that addresses ambiguities in public international law while ensuring damages reflect economic realities. The contextual approach adopted by tribunals arises from the lack of universally binding norms governing the application of compound interest in public international law, resulting in no singular directive. This gap grants tribunals significant latitude to reference commercial practices and specific treaty language, enabling them to fill the interpretive void with normative judgments that reflect industry standards and the unique circumstances of each case.[82]

The gaps in public international law highlight the need to clearly define compound interest within a structured legal framework. However, as this analysis shows, even in a more cohesive system, classifying compound interest as purely procedural or substantive remains difficult.[83] Public international law struggles with this not due to a lack of clarity, but because of the dynamic and complex nature of its instruments, which makes rigid classification impractical. This complexity demands a more flexible understanding of legal practice and financial relationships.[84] The next key question is how international law classifies legal mechanisms and the criteria used to determine whether they are procedural or substantive, which will be addressed in the following sections.

IV. “Proceduralization” in Public International Law: A Contextual Analysis for Attaining Shared Goals

In public international law, “proceduralization” is recognized as a significant jurisprudential tool, with procedural norms assuming a quasi-substantive role.[85] This analysis illustrates that procedural mechanisms are not merely about the processes of law; they also influence the substantive outcomes of legal disputes, highlighting their importance in achieving justice and common objectives within the international legal framework.

One of the leading scholars in the field of proceduralization, Jutta Brunnée argues that procedural obligations act as essential “yardsticks” for measuring compliance with broader substantive norms.[86] This transformation turns abstract compliance thresholds into concrete, actionable duties.[87] She emphasizes the Environmental Impact Assessment (EIA) as a prime example, illustrating its critical role in operationalizing and assessing substantive obligations, such as preventing transboundary harm.[88] Brunnée regards procedure as a potent instrument that can, in practical terms, either generate or undermine substantive rights.[89] She argues that in environmental law, procedural obligations such as due diligence measures are crucial for fulfilling substantive commitments, as seen in International Court of Justice (ICJ)   cases like Pulp Mills on the River Uruguay,[90] and Certain Activities Carried Out by Nicaragua in the Border Area.[91] Here, proceduralization solidifies the duty to prevent environmental harm, requiring states to conduct EIAs and provide transparency to substantiate their compliance with environmental standards. These examples illustrate that the contextualization of substantive law within a procedural framework can occur unconsciously unless approached with deliberate intent.[92] Substantive law is designed to achieve specific outcomes, and effective compliance often hinges on a clear connection to the procedural law that is expected to support it.[93] Nina Le Bonniec has aptly characterized this intricate interplay as the “progressive effacement” of the distinction between procedural and substantive obligations within the human rights regime.[94]

Le Bonniec observes that as procedural norms become more integral, they increasingly adopt quasi-substantive roles.[95]  He views proceduralization as a potent legal mechanism used by the European Court of Human Rights (ECtHR) to enforce substantive rights actively and effectively.[96] Through procedural obligations, the Court extends accountability by requiring states to take proactive steps, such as enacting laws and conducting investigations, thus ensuring they not only refrain from violating rights but also actively uphold them. [97]  The quasi-substantive role of procedural rights is also evident in some laws embedded in Human Rights Law.[98] For instance, Despina Sinou examines the relationship between substantive rights (like freedom from torture) and procedural guarantees (e.g., effective investigation into violations). These procedural mechanisms ensure that states meet their substantive human rights obligations.[99] 

In addition to facilitating the practical application of substantive rights, procedural obligations, as noted by Le Bonniec, can serve as “jurisprudential tools” that promote broader policy objectives by harmonizing national law.[100] This jurisprudential policy is intertwined with the decision-maker’s discretionary power as a matter of “interpretative choice.”[101] Le Bonniec asserts that proceduralization facilitates the harmonization of human rights standards across different jurisdictions.[102] This flexible framework adapts to various legal systems, promoting a standardized approach to rights without compromising national sovereignty.[103] For example, procedural requirements, such as fair trials, create a shared procedural foundation aligned with substantive rights, supporting a cohesive European rights model.[104] Finally, proceduralization grants the adjudicative mechanisms interpretative flexibility.[105] By categorizing specific actions as procedural obligations, the Court can adjust its rulings in accordance with evolving standards and societal expectations, thereby providing a clear framework for interpretation that allows for adaptability and responsiveness to new contexts and human rights challenges.[106] A significant implication of this perspective is that procedural obligations are largely shaped by tribunals’ institutional and structural policy preferences rather than determined solely by legal interpretation.[107]

In the context of compound interest in public international law, a key question arises, particularly when considering Le Bonniec’s critique of proceduralization. He argues that proceduralization is not merely a straightforward application of law, but rather a “jurisprudential policy.”[108] This raises the question: do tribunals in investment arbitration use their discretionary powers to go beyond the conventional understanding of substantive norms, like compound interest, and embrace a more flexible interpretation?

The answer to this question is far from simple. One could contend that the proceduralization framework inherent in public international law offers tribunals a distinct perspective through which they can justify the awarding of compound interest.[109] By applying Le Bonniec’s theory of “proceduralization”—which emphasizes the primacy of function and context—tribunals can recast compound interest not just as a financial mechanism but as a strategic policy tool.[110] This approach enables tribunals to reconcile the application of compound interest with the broader principles of justice and equity that underpin investment arbitration.[111]

However, this issue cannot be examined in isolation. To understand whether tribunals can move beyond rigid normative classifications, we must first explore how procedural frameworks, such as the one Le Bonniec discusses, offer tribunals the flexibility to reinterpret established norms.[112] By adopting the proceduralization model, investment tribunals are not constrained by traditional views of compound interest as a mere legal instrument.[113] Instead, they can view it as a malleable tool, adaptable to the larger goals of fairness and policy considerations in investment arbitration. The following sections will delve deeper into Le Bonniec’s theory and demonstrate how tribunals can reframe compound interest as a policy-driven, strategic instrument that aligns with broader jurisprudential goals.

V. Balancing Predictability and Purpose: Conflict of Law Analysis vs. the Goal-Oriented Nature of Constitutional Law

In addition to public international law, constitutional law attributes primacy to context-based and function-oriented criteria to determine whether a norm falls within the substance-procedure dichotomy.[114]  The codification of both procedure and substance plays a crucial role in the constitution, serving as the foundation for its fundamental principles.[115] Within the constitutional framework, the practice of codifying norms is influenced by contextual factors and policy considerations.[116] Constitutional rights shape the boundary between intrinsic rights and their legal framing, with the distinction reflected in “representation-reinforcement.”[117]

Based on constitutional perspectives, substantive rights—such as those enshrined in the Second Amendment of the U.S. Constitution[118]—possess intrinsic significance that transcends specific legal procedures.[119] These rights operate independently and are not wholly dependent on procedural frameworks.[120] Their unique characteristic lies in their ability to serve as the bedrock for fundamental freedoms and protections, standing firm regardless of the procedural mechanisms in place.[121]

Scholars like Richard Posner, [122] John O. McGinnis,[123] and Michael B. Rappaport examine substantive rights through a pragmatic and consequentialist lens. They characterize these rights as integral to decision-making processes that prioritize the moral desirability of outcomes.[124] In line with Posner’s perspective, substantive rights are seen as enhancing the original meanings of the U.S. Constitution, ultimately leading to improved social outcomes and making this approach normatively preferable.[125] By emphasizing the moral implications and consequences of legal decisions, these theories position intrinsic rights as essential components in the pursuit of justice and social welfare.[126] They serve as a guiding principle at the forefront of legal interpretation and application, ensuring that the protection of these rights remains a priority in the constitutional framework.[127] While substantive rights aim to guide decision-making toward morally desirable outcomes, procedural norms, viewed through a constitutional lens, ensure that decision-making adheres to principles of fairness and legitimacy, necessitating that certain constitutional decisions be entrusted to specific institutional actors.[128]

While substantive rights aim to guide decision-making toward morally desirable outcomes,[129] procedural norms, viewed through a constitutional lens, ensure that decision-making adheres to principles of fairness and legitimacy, necessitating those certain constitutional decisions be entrusted to specific institutional actors.[130] The ideology underpinning procedural norms is grounded in democratic principles, as exemplified by John Hart Ely’s representation-reinforcement theory, which emphasizes the importance of procedural issues over substantive ones to maintain the democratic legitimacy of judicial review.[131] Likewise, procedural rights embody the concept of popular sovereignty, asserting that judges, as agents of the constitutional framework, possess the discretion to shape and uphold constitutional norms and principles.[132]

While procedural rights are designed to protect democracy, their significant role was initially perceived as independent safeguards guiding judicial decision-making.[133] The inclusion of the right to a civil jury trial in the Constitution highlights the entrenchment of procedural rights as essential to preserving substantive justice.[134] This grants them a dual role: preserving democratic integrity and reinforcing substantive rights, ensuring justice and fairness.[135] While procedural rules may seem purely technical, a new stream exists that aims to foster substantive rights and promote broader societal goals like fairness, privacy, and balance in legal proceedings.[136] Within this stream, substantive norms are shaped by expectations about procedural rules, such as pleading rules, discovery scope, evidence rules, trial practice, and other built-in procedural expectations.[137]

In this context, procedure is inherently substantive and cannot be dismissed as trivial, despite the subordinate role suggested by the substance-procedure dichotomy. The perception of procedure as insignificant is not only misleading but can also be strategically exploited. Substantive decisions may be cloaked in procedural guise, while procedural determinations can effectively function as proxies for substantive impacts, thereby influencing the legal landscape in profound ways.[138] This narrative is well-known.[139] A brief overview of the literature suffices to illustrate that procedural mechanisms can yield substantive outcomes, regardless of intent.[140] The metaphors surrounding the substance-procedure dichotomy underscore this point: adjectives can distort the meaning of sentences, pipes can leak or contaminate, handmaids can ascend to the status of mistresses, and player pianos can be so out of tune that the music becomes unrecognizable.[141]

Both constitutional law and public international law endorse context-based and function-oriented criteria to determine whether a norm falls within the substance-procedure dichotomy.[142] In international arbitration, when arbitrators address the rate of interest, they typically refer to the parties’ agreement for any explicit provisions on the matter.[143] However, if the agreement is silent or ambiguous regarding interest, arbitrators usually conduct a choice-of-law analysis to select the applicable law of a specific country to resolve the interest claim.[144] This conflict of law analysis enables tribunals to balance local statutory rates with broader commercial considerations. Unlike constitutional frameworks, conflict of law analysis is inherently arbitrary when distinguishing between substantive and procedural law, particularly in complex cases.[145] Nonetheless, this classification is crucial for courts to determine which aspects of a dispute are governed by the law of the forum (lex fori) and which by foreign law.[146] Procedural laws are generally dictated by the forum state to align with local standards, while substantive laws are drawn from the jurisdiction most closely connected to the underlying rights.[147]

Reflecting practical concerns about the enforceability of foreign judgments, tribunals identify the most appropriate rules to address the procedural-substantive divide.[148] This distinction is deeply rooted in the principles of fairness and predictability in cross-border litigation, emphasizing certainty and clarity to promote uniform results across different legal systems.[149] It embodies the foundational concepts of private international law, encapsulated in the “vaunted virtues” of this framework.[150]

In conflict of law, the line-drawing process is guided by the “convenience of the forum,”[151] emphasizing the practicality of applying a foreign jurisdiction’s substantive law within the forum’s procedural framework.[152] Unlike constitutional law, which distinguishes norms based on their purpose, or public international law, which focuses on their function in advancing public policy, conflict of law prioritizes minimizing complications in proceedings.[153]  It aims to balance substantive rights from foreign jurisdictions with procedural coherence in its own legal system, thereby promoting predictability.[154]

Conversely, in constitutional contexts, the distinction between substance and procedure is defined more rigidly to protect individual rights and democratic values.[155] In contrast, conflict of laws allows for procedural flexibility to achieve fairness and efficiency.[156] Ultimately, constitutional frameworks prioritize fundamental rights over procedural convenience, reflecting a stronger commitment to systemic justice.[157] Nevertheless, the codification of norms based on their legal context and jurisdictional foundation has resulted in a somewhat binary approach to norm categorization,[158] overlooking the potential for overlap and intersectionality between norms.[159] A critic has observed that, although the procedural-substantive distinction within conflict of law may appear well-defined, it lacks clear parameters, and leads to inconsistent application and ambiguity.[160] As a result, courts may encounter difficulties in assessing whether a rule sufficiently impacts substantive rights to warrant overriding the procedural norms of the forum.[161]

Having established the link between substance and procedure, it is clear that the procedures used can greatly affect substantive outcomes, especially in investment arbitration. The following sections will focus on two main points: First, that compound interest, when viewed through the lens of public international law, is a flexible legal tool with a dynamic role. Second, that by moving beyond strict classifications, compound interest can better align with principles of equity, full reparation, and procedural fairness.

VI. The Evolving Jurisprudence of Compound Interest in Investment Arbitration

The classification of compound interest as a distinct legal instrument raises important questions about its evaluative framework. Should one analyze it under public international law, or does conflict of laws have the authority to define it as a norm? Each perspective carries significant legal implications that warrant examination through the jurisprudence of investment tribunals.

1. The Restitutionary Purpose of Compound Interest.

When viewed through the lens of public international law, the delineation of boundaries is shaped by a contextual framework that aligns with its intended purpose. In this context, the role of compound interest becomes central.[162] As previously established, the principle of “full reparation” is a fundamental remedial mechanism, and compound interest plays a crucial role in achieving this goal.[163] Compound interest ensures not only the restoration of the principal but also the returns that would have accrued over time, reinforcing the restitutionary power of compensation. This was exemplified in Odyssey Marine Exploration, Inc. v. Mexico,[164] whereby the claimant sought both pre- and post-award compound interest under NAFTA Article 1135 and Article 38 of the ILC Articles on State Responsibility.[165] The tribunal upheld its authority to award interest, citing the right to full reparation.[166] It awarded interest from October 12, 2018 until full payment, using the rate of the one-year Mexico Treasury bond, compounded annually.[167] By applying a uniform formula across both pre- and post-award periods, the tribunal reinforced that compound interest is not merely a procedural add-on but a substantive mechanism of compensation.[168] However, it exercised its procedural discretion in determining the interest rate and compounding frequency.[169] The tribunal rejected the claimant’s proposed weighted average cost of capital (13.95%), and opted instead for the one-year Mexican Treasury bond rate with annual compounding.[170]

Similarly, in Kardassopoulos v. Georgia,[171] the tribunal’s reasoning was firmly anchored in both legal principles and precedent.[172] It referenced Article 38 of the ILC Articles on State Responsibility, which permits the award of interest ”when necessary . . . to ensure full reparation.”[173] Drawing from Compañía del Desarrollo de Santa Elena v. Costa Rica, the tribunal emphasized that compound interest is not a penalty, but a means of ensuring that claimants are compensated for the time value of money lost due to delays in payment.[174] Echoing the Santa Elena decision, the tribunal highlighted that a state should not profit from such delays, and while simple interest may be easier to calculate, it can be arbitrary and inconsistent with economic realities of borrowing and investment.[175] In this light, the tribunal reaffirmed that compound interest is a legitimate compensatory tool in international law.[176] In assessing compound interest, the tribunal inadvertently bifurcated the issue: the viability of compound interest is grounded in precedent and the principle of full reparation, while the methodology—rate, uplift, and compounding interval—remains subject to the tribunal’s discretion.[177] This approach illustrates a broader trend in contemporary arbitral jurisprudence: while compound interest is increasingly recognized as a substantive entitlement, its precise formulation remains within the tribunal’s discretionary judgment. Similarly, in Wena Hotels Limited v. Arab Republic of Egypt,[178] the tribunal justified compound interest based on industry standards, where compounded returns are common, ensuring the award met the claimant’s expectations.[179]

2. Avoiding Unjust Enrichment for Both Investors and Host States

A key aspect of compound interest is its capacity to accumulate interest on both the initial principal and the interest already earned.[180] This feature not only aligns with contemporary international practices but also reinforces the substantive principles of financial equivalence and economic efficiency.[181] By accurately reflecting the true cost of borrowing, compound interest helps prevent unjust enrichment for the debtor and serves as a crucial deterrent against financial advantage.[182]  This framework aligns with the goal of ensuring that compensation mechanisms reflect real-world financial practices, upholding the principles of liquidity management.^[183]  In doing so, tribunals aim to ensure that compensation mechanisms in investment arbitration reflect practical financial behavior, particularly with respect to liquidity management principles when dealing with sovereign states.^[184] While respondents’ borrowing costs are significant, sovereign states and large corporations may strategically delay payments to maintain financial capacity.[185] These entities often have access to capital markets and can borrow at competitive compound interest rates, raising concerns about unjust enrichment when funds are withheld.^[186]

3. Ensuring the Accuracy and Predictability of Award Payments through Compensation

In addition to serving as a compensatory mechanism, the function of compound interest also plays a critical role in maintaining fairness and ensuring the timely execution of awards. By encouraging prompt payments and preventing delays that could be exploited, compound interest acts as a procedural tool to uphold the integrity of dispute resolution processes.[187] A key example of this is found in the case of VercarA LLC v. Republic of Colombia.[188] Similarly, in ICS Inspection and Control Services Ltd v. Argentina,[189] the tribunal addressed the issue of interest within the broader context of the claimant’s right to compensation.[190] The tribunal began by grounding its reasoning in the principle of full reparation, citing Article 38 of the ILC Articles on State Responsibility, which states that interest is due “where necessary to ensure full reparation”.[191] This placed the entitlement to interest within the substantive framework of international law, positioning it as part of the claimant’s right to be restored to the position it would have been in had the wrongful act not occurred.[192]

The tribunal then turned to arbitral practice, acknowledging that there is no uniform rule in international law about whether simple or compound interest should be applied.[193] It noted that past awards have shown varying approaches: some tribunals prefer simple interest for its simplicity, while others opt for compound interest, which reflects commercial realities more accurately.[194] This diversity highlighted that, although the principle of awarding interest is substantive, the choice of method is left to the discretion of the tribunal. Ultimately, the tribunal decided to award interest at six-month USD LIBOR plus two percent , with annual compounding, from the date of expropriation until payment.[195] While the tribunal did not provide extensive justification for its choice of rate or compounding frequency, it emphasized that these decisions are a matter of case-specific discretion, rather than rigid rules.[196]

Importantly, the tribunal did not explicitly separate substance from procedure in its reasoning. It did not categorize interest as strictly one or the other. However, by linking the entitlement to interest to the substantive principle of full reparation and treating the methodology of calculation (e.g., rate, frequency, and start date) as a matter of discretion, the tribunal subtly reflected the substance–procedure divide without formally acknowledging the divide[197]

Similarly, in Ampal-American Israel Corp. v. Arab Republic of Egypt,[198] the tribunal emphasized that awarding compound interest was essential for ensuring full reparation, aligning with commercial norms and preventing strategic delays. Compound interest has been likened to the economic cost of non-compliance, and this decision clearly indicates a policy stance: parties that breach their obligations cannot benefit from delay tactics without facing additional financial liability[199]

The alignment of compound interest with established economic practices within the legal framework is not merely theoretical but reflects a critical and practical mechanism that ensures fairness, consistency, and predictability in arbitral outcomes. By integrating compound interest into arbitration awards, the legal process acknowledges the economic realities of commercial and investment markets, where capital appreciates over time through compounding.[200] In this regard, when an investor is deprived of their funds, they suffer not only the loss of the principal but also the compounded returns that would have accrued.[201] To ignore this fundamental economic truth in arbitration decisions would result in under compensation, placing claimants at an unfair financial disadvantage. This cannot be justified if we are to uphold the principles of economic fairness. Compound interest, in this sense, is not a mere financial detail but a core component of ensuring that arbitral decisions are consistent with the realities of modern economic life.[202] The tribunal’s emphasis on compound interest as a quasi-procedural tool highlights the growing recognition of its role beyond being just a substantive legal principle.[203] Compound interest serves a dual purpose; first, it ensures that delayed payments are met with a genuine financial penalty, creating a powerful deterrent against delay.[204] This mechanism thus serves not only to protect the economic interests of claimants, but also to promote the efficiency of legal proceedings.

This brings us to a crucial question: does the process, through the application of compound interest, achieve the right balance of fairness, harmony, and predictability? Predictability, in this context, ensures that claimants receive the full value of their award, with compound interest serving as a tool to enforce substantive law and maintain consistency in financial compensation.[205] If legal processes are to be effective, they must encourage behaviors that prioritize the timely resolution of disputes and discourage the tactics that prolong and complicate litigation.

Procedurally, the application of compound interest is not merely a theoretical concept; it is a vital instrument in achieving effective dispute resolution. It acts as a deterrent, ensuring that the integrity of the arbitration process is maintained. When a tribunal employs compound interest, it forces litigants to recognize the financial consequences of delayed payments, thus promoting a more efficient and timely resolution of disputes. Like compound interest itself, this procedural tool influences litigation behavior, creating winners and losers by encouraging compliance with deadlines and payment schedules.

However, it is essential to understand that no procedural decision can be entirely neutral, as even procedural mechanisms like compound interest are inherently influenced by the substantive context of the dispute. The growing body of ICSID case law, including landmark cases such as Wena Hotels v. Egypt and LG&E v. Argentina,[206] underscores the significance of awarding compound interest.[207] Tribunals have increasingly acknowledged that compound interest is crucial for accurately reflecting economic realities and ensuring that claimants are not financially disadvantaged by delayed compensation.[208] These decisions illustrate the broader principle that substantive rights must be protected by ensuring that the compensation awarded aligns with the economic realities of the situation. In Continental Casualty Co v. Argentina,[209] this principle was further solidified, confirming that compound interest is not just an accessory, but a substantive tool that guarantees fairness in arbitration awards.[210] These decisions collectively signal a clear trend in ICSID jurisprudence towards the integration of compound interest as a means of achieving economic fairness, enhancing predictability, and supporting the integrity of the arbitration process.

The table below provides an initial analysis of recent case law, highlighting the various roles and applications of compound interest in arbitration.[211]

Interest Rate Parameters	Primary Considerations	Descriptions
Compensation for Delay and Loss of Use	Substantive	Ensures that claimants receive compensation for the time value of money lost due to delayed payments, restoring potential investment returns they would have gained.
Prevention of Unjust Enrichment	Substantive	Upholds equity principles by preventing respondents from unfairly benefiting from funds owed to claimants, ensuring no profit from delayed payments.
Promotion of Efficient Dispute Resolution	Procedural	Encourages prompt resolution of disputes by making delays costly, supporting efficiency and reducing the backlog in legal and arbitration systems for societal benefit.
Fair and Equitable Compensation	Substantive	Adheres to legal standards promoting fair and proportional compensation, aligning with international norms that ensure equitable treatment of claimants.

VII. Exploring the Substance-Procedure Antinomy: The Role of Compound Interest in Achieving Substantive Justice

This article seeks to establish that the characterization and application of compound interest can be enhanced by considering it through the framework of a substance-procedure dichotomy. This duality reveals the dynamic nature of compound interest, illustrating its function as both a procedural mechanism and an essential instrument for the attainment of substantive justice within legal contexts. In this context, it suggests that establishing a strict dichotomy and imposing a singular label on norms like compound interest, along with assigning consequences to that label, would be unwise and could have significant repercussions for three key reasons.

First, the substance-procedure dichotomy carries considerable jurisprudential responsibilities concerning the application, legal classification, and role of compound interest.[212] However, it struggles to effectively support such a demanding structural burden in legal practice.[213] Rigid categorizations of norms often create a hierarchy that favors substantive law over procedural frameworks,[214] portraying substantive norms as superior and linked to fundamental rights, while relegating procedural norms to a mere supportive role.[215]  This perspective, reinforced by metaphors likening procedure to infrastructure, diminishes the importance of procedural norms and reduces concepts like compound interest to  ”adjective law”, undermining their broader significance.[216] Even reformist efforts, such as those by David Dudley Field, have perpetuated the view of procedure as a secondary facilitator rather than an essential legal component.[217] This maneuver is dangerous because procedural reforms can have the effect of denying substantive rights due to its intertwined nature with procedural rights.[218] 

To assume substantive rights to be procedural or trans-procedural, one disregard the fact that it is constructed with a specific procedural apparatus in mind to vindicate the rights created or the responsibilities assigned by that substantive law.[219] The intertwined and non-binary nature of procedural norms is highlighted by Sabrina Robert-Cuendet,[220] who notes that in investor-state arbitration, tribunals often derive procedural elements from substantive obligations to ensure enforceable investor protections.[221] This demonstrates how proceduralization can transform general obligations, like fair and equitable treatment, into procedural norms by incorporating requirements for due process and transparency in state actions.[222]  Similarly, substantive norms, for instance the application of damages in arbitral awards, relies on procedures such as the document evidence, cross-examination of experts and engaging in standard of proof to effectuate its mandate.[223] Substantive law, exemplified by the principle of “full reparation,” cannot function effectively without procedural mechanisms.[224] Therefore, employing compound interest as a procedural tool to bypass delays in damage payments—intended to serve deterrent objectives—ultimately renders it ineffective and hollow. Critically, when focusing on fairness and deterrent objectives, compound interest can be viewed as a procedural mechanism that supports substantive goals, such as prompt payment and the prevention of delays and obstruction of due process. This underscores how compound interest upholds fundamental principles like justice while being intrinsically linked to substantive outcomes. The emergence of quasi-procedural norms underscores the inherent ambiguity of the substance-procedure dichotomy. As Professor John Hart Ely observed, we are all aware of the nuanced and fluid nature of this distinction.[225] Rigid adherence to fixed categorizations undermines the law’s richness and its capacity for layered interpretations. Consequently, a strict classification of compound interest constrains its operation within the grey area between substance and procedure, imposing a narrow definition that fails to acknowledge its multifaceted purpose.

Secondly, the rise of quasi-procedural norms highlights that it is not surprising the boundaries of the substance-procedure dichotomy remain unclear, if not entirely chaotic. Yet, the rigid adherence to fixed categorizations negates the richness of laws and legal norms, multiple intentions, and their capacity for layered, nuanced interpretations.[226] Thus, this strict classification of compound interest eliminates the conceptual space for legal concept such as compound interest to operate in the grey area between substance and procedure, instead forcing a narrow definition that overlooks its multifaceted purpose.

By reducing the concept to a singular procedural or substantive function, the legal framework risks overlooking the complex, integrated role that compound interest plays across diverse legal and commercial contexts. This narrow perspective threatens to compromise the adaptability and fairness of arbitration, particularly in investor-state disputes, where financial assessments require contextual flexibility.  This fluidity allows compound interest to adjust to changing conditions and highlights its essential role in a complex, commercially driven context.

The rigid proceduralizations may restrict interpretive flexibility, limiting tribunals’ ability to consider economic realities, commercial reasonableness, and evolving legal norms. In the context of investment arbitration’s public-private divide, arbitrators are often likened to judges, which entails an expectation to endorse customary norms and provide reasoned applications of compound interest.[227] This duty is essential for lending legitimacy to the arbitration process.[228] Despite the ”investor-state””[229] configuration, these proceedings are fundamentally international and directly involve states, requiring arbitrators to prioritize global principles and public standards.[230] Consequently, the adjudicative process must apply definitions of “investment,” property character, and public policies through an international lens, balancing the objectives of international investment law with the unique considerations of public international law.[231] Crucially, arbitrators’ discretion to set aside the overarching jurisprudence of conflict of laws, when determining compound interest, is consistent with the principles of predictability and transparency that are fundamental to investor-state arbitration.[232] This flexibility enables them to emphasize standards that promote fair and equitable treatment, ensuring that predictability is not compromised by complex or conflicting jurisdictional doctrines.[233]

The public law aspect of investment arbitration requires arbitrators to engage more comprehensively in the thorough evaluation of international public policy and social welfare principles related to the applicable compound interest and its effects on a country’s credit borrowing risks. This entails that arbitrators must consider the expectations of the global public, a responsibility not typically faced by those in private international law, where predictability and public policy concerns are primarily limited to the parties involved in the dispute. As a result, arbitrators must seek to achieve a proper balance between fairness for both investors and host states, predictability in the quantification of damages, and jurisdictional integrity in the broader context of damage assessment and timely payment.

This article advances a set of interrelated propositions designed to reconceptualize the role of compound interest within legal doctrine. At its core, compound interest is recognized as serving a dual function: procedurally, it promotes timely payment and discourages delay; substantively, it ensures fairness, reinforces deterrence, and facilitates the effective enforcement of legal rights. Its multifaceted nature renders it incompatible with a rigid classification as either purely procedural or purely substantive.

Furthermore, the article emphasizes the importance of moving beyond the traditional dichotomy between substance and procedure. Compound interest functions as a legal norm that bridges both realms, influencing both the timing of legal processes and the substantive fairness of outcomes. Its application requires flexibility, accommodating evolving economic conditions, legal standards, and the specific nuances of each dispute, particularly in complex fields like investment arbitration.

Finally, in the context of investment arbitration, compound interest must be contextualized within the broader framework of international public law. Its application entails balancing the interests of investors and states, fostering fairness, predictability, and consistency in arbitral decisions.

Conclusion

The intersection of substantive and procedural law in investment arbitration, particularly in the treatment of compound interest, highlights the fluidity and complexity of legal principles that underlie arbitral decision-making. This article has examined how rigid classifications of compound interest as either substantive or procedural often fail to capture its true legal and economic roles. The dichotomy, while foundational, fails to acknowledge the practical and flexible applications that compound interest serves, both as a mechanism of full reparation and a procedural tool to enhance fairness and discourage delay. Through the lens of public international law and proceduralization, it becomes clear that compound interest is not a static concept but one that evolves according to the specific needs of each case. It is a tool for ensuring equity and maintaining economic fairness, allowing tribunals to address the financial realities of delay and under compensation. Its role as both a substantive safeguard and a quasi-procedural mechanism demonstrates that the strict procedural-substantive divide is not only conceptually fragile but practically limiting. Arbitral tribunals, by embracing the flexibility of compound interest, can better navigate the complexities of investor-state disputes, ensuring that compensation reflects true economic losses and maintains consistency across cases.

The call for a more nuanced, functional approach is not merely theoretical—it is essential for the future of international arbitration, where the balance of fairness, predictability, and justice is paramount. By treating compound interest as a flexible, multifaceted tool, legal professionals can ensure its effective use in promoting both procedural efficiency and substantive justice. This perspective allows compound interest to adapt to the unique circumstances of each dispute, particularly in complex commercial and international legal settings, ensuring fairness and the proper enforcement of rights. In the evolving landscape of investment arbitration, a flexible, context-driven understanding of compound interest can guide tribunals toward more equitable and commercially realistic awards, fostering a legal environment where both substantive rights and procedural tools work synergistically to achieve just outcomes.

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[1] See Jonathan Bonnitcha et al., Damages and ISDS Reform: Between Procedure and Substance, at 3–5 (Draft Manuscript, Aug. 7, 2021).

[2] See Naimeh Masumy, The Legal Framework Governing Interest Rates Under Public International Law—Part 1, Daily Jus (Nov. 21, 2024), https://dailyjus.com/world/2024/11/part-1-the-legal-framework-governing-interest-rates-under-public-international-law.

[3]See Bonnitcha, supra note 1, at 4–6.

[4] Id. at 2, 8, 7.

[5] Id. at 4, 9.

[6] Factory at Chorzow (Germ. v. Pol.), 1928 P.C.I.J. (ser. A) No. 17 (Sep. 13, 1928).

[7] Id. at 28.

[8] Int’l Law Comm’n, Articles on Responsibility of States for Internationally Wrongful Acts, United Nations, arts. 31–36 (2001).

[9] Id. arts. 3, 33.

[10] Irmgard Marboe, Calculation of Compensation and Damages in International Investment Law (2d ed. 2017).

[11] John Smith, The Role of Compound Interest in Investment Arbitration, 45 J. Int’l Arb. 44 (2023); See also Peter Birks, ‘Recovery of Compound Interest as Restitution for Damages’ in William R Cornish and others (eds), Restitution: Past, Present and Future—Essays in Honour of Gareth Jones (Hart Publishing 2008).

[12] Sempra Energy Int’l v. Argentine Republic, ICSID Case No. ARB/02/16, Award (Sep. 28, 2007).

[13] Autopista Concesionada de Venezuela, C.A. v. Bolivarian Republic of Venezuela,ICSID Case No. ARB/00/5, Award (Sep. 23, 2003).

[14] [[]]Sempra Energy Int’l v. Argentine Republic, ICSID Case No. ARB/02/16, Award, ¶ 403 (Sep. 28, 2007); Autopista Concesionada de Venezuela, C.A. v. Bolivarian Republic of Venezuela, ICSID Case No. ARB/00/5, Award ¶¶ 100–02 (Sep. 23, 2003).

[15] Marboe, supra note 10, at 45; see also Christoph Schreuer et al., The ICSID Convention: A Commentary (2nd ed. 2009) 1108–1110.

[16] Marboe, supra note 10, at 45

[17] Schreuer, supra note 15, at 1225–1227.

[18] Sidney Homer & Richard Sylla, A History of Interest Rates 73 (3d ed. 1991); see also see also R. H. Davies, “Interest as Damages in International Arbitration” (2005) 20(1) Arbitration International 21, 43 (“tribunals failed to adopt a rational and uniform approach for evaluating interest claims”

[19]See generally Marboe, supra note 10

[20] Id. at 101.

[21] Id. at 40.

[22] N. Masumy, “The Legal Framework Governing Interest Rates Under Public International Law – Part 1”, Daily Jus (21 November 2024)

[23] William W Park, Arbitration’s Protean Nature: The Value of Rules and the Risks of Discretion (adapted from Freshfields Lecture, London, December 2002), 19 Mealey’s Int’l Arb. Rep. 1, 10 (2004).

[24] Compañía del Desarrollo de Santa Elena SA v. Republic of Costa Rica, ICSID Case No. ARB/96/1, Final Award, ¶ 104 (Feb. 17, 2000).

[25] Sempra Energy International v. Argentine Republic, ICSID Case No. ARB/02/16, Award, ¶ 403 (Sep. 28, 2007).

[26] LG&E Energy Corp, LG&E Capital Corp, and LG&E International Inc v. Argentine Republic, ICSID Case No. ARB/02/1, Award, ¶ 55 (July 25, 2007).

[27] [[Please verify Emily’s FN30a source is correct]] Borzu Sabahi, Compensation and Restitution in Investor-State Arbitration: Principles and Practice (OUP 2011) 163; Michele Potestà, Interest in International Investment Arbitration, 31 J. Int’l Arb. 409 (2014).

[28] S. Pac. Props. (Middle East) Ltd. v. Arab Republic of Egypt, ICSID Case No. ARB/84/3, Award (May 20, 1992).

[29] Id. ¶ 390.

[30] Desert Line Projects LLC v. Republic of Yemen, ICSID Case No. ARB/05/17, Award (Feb. 6, 2008).

[31] Id. ¶¶ 301, 303.

[32] Neelabh Niket & Rahul Pandey, Post-Award Interest Can Be Granted By An Arbitrator On The Interest Amount – Supreme Court Reiterates (Apr. 30, 2025), https://www.mondaq.com/india/trials-appeals-compensation/1617374/post-award-interest-can-be-granted-by-an-arbitrator-on-the-interest-amount-supreme-court-reiterates John Y Gotanda, “Compound Interest in International Disputes” (2007) 3 Transnational Dispute Management

1, 4. Smith, “The Role of Compound Interest in Investment Arbitration” (2023) 45 Journal of International Arbitration 43.

[33] Wöss H, San Román Rivera A, Spiller PT, Dellepiane S, Damages in International Arbitration under Complex Long-Term Contracts, in [[book, check citation form]] Wöss H, San Román Rivera A, Spiller PT, Dellepiane S (eds), Damages in International Arbitration under Complex Long-Term Contracts (Oxford University Press 2014) 129.

[34] LG&E Energy Corp. v. Argentine Republic, ICSID Case No. ARB/02/1, Award (July 25, 2007).

[35] PSEG Glob. Inc. v. Republic of Turkey, ICSID Case No. ARB/02/5, Award (Jan. 19, 2007).

[36] LG&E Energy Corp. v. Argentine Republic, ICSID Case No. ARB/02/1, Award, ¶ 56 (July 25, 2007); PSEG Glob. Inc. v. Republic of Turkey, ICSID Case No. ARB/02/5, Award, ¶ 284 (Jan. 19, 2007).

[37] NextEra Energy Glob. Holdings BV v. Kingdom of Spain, ICSID Case No. ARB/14/11, Award, ¶¶ 663–74 (Mar. 12, 2019).

[38] Tethyan Copper Co. Pty v. Islamic Republic of Pak., ICSID Case No. ARB/12/1, Award (July 12, 2019).

[39] Id. ¶ 1792.

[40] Tigran Poghosyan, Long-run and Short-run Determinants of Sovereign Bond Yields in Advanced Economies, 38 Econ. Sys. 100 (2014).

[41] Hamadi Al Tamimi v. Sultanate of Oman, ICSID Case. No. ARB/11/33, Award (Nov. 3, 2015)(The award. Post-Award interest shall be payable on these costs as from 60 days after the date of the issue of this Award. Interest shall be calculated at the 91-day US Treasury Bill rate and compounded quarterly).

[42] Id. ¶ 481.

[43] Id.

[44] Bahgat v. Arab Republic of Egypt, PCA Case No. 2012-07, Award (Dec. 23, 2019) (Damages interest: LIBOR + 2%; Costs interest: LIBOR + 4%).

[45] Id. ¶ 618(I).

[46] The Rotten Heart of Finance, The Economist (7 July 2012), https://www.proquest.com/docview/1024125546?accountid=8285&sourcetype=Magazines [perma link??].

[47] Calculating Interest in International Arbitration: How is Interest Determined?, Aceris Law LLC (Oct. 30 2020), https://www.acerislaw.com/calculating-interest-in-international-arbitration-how-is-interest-determined/..

[48] Tidewater Inv. SRL v. Bolivarian Republic of Venez., ICSID Case No. ARB/10/5, Award (Mar. 13, 2015).

[49] Id.¶ 205.

[50] Compañía del Desarrollo de Santa Elena S.A. v. Republic of Costa Rica, ICSID Case No. ARB/96/1, Award (Feb. 17, 2000).

[51] Id. ¶ 100.

[52]  Compania del Desarrollo de Santa Elena SA v Costa Rica Compañía del Desarrollo de Santa Elena SA v Costa Rica (ICSID Case No.ARB/96/1, Final Award, 17 February 2000) at [104]. (recommend using “Contra” “with” signal to compare sources here.

[53] Adel A. Hamadi Al Tamimi v Oman, ICSID (Case No.ARB/11/33), Award, 3 November 2015 at [481]. The award. Post-Award interest shall be payable on these costs as from 60 days after the date of the issue of this Award. Interest shall be calculated at the 91-day US Treasury Bill rate and compounded quarterly.; see also Discovery Global LLC v Slovak Republic, ICSID (Case No.ARB/21/22), Award, 10 January 2025 at 712–713;

[54] South American Silver v Bolivia, PCA Case No.2013-15, Award at [784]–[786]. Recalibrating compound interest in investment arbitration: sovereign borrowing costs, grace periods, and economic equity | Westlaw Advantage UK.

[55] David J. Branson, and Richard E. Wallace Jr., “Awarding Interest in International Commercial Arbitration: Establishing a Uniform Approach.” (1988) 28 Virginia Journal of International Law 919.

[56] William W. Park, Arbitration’s Protean Nature: The Value of Rules and the Risks of Discretion, 19 Mealey’s Int’l Arb. Report 1, 10 (2004).

[57] Gary B. Born, International Commercial Arbitration, 2nd ed. (Kluwer Law International 2014) (discussing the role of party autonomy and the discretion of tribunals in arbitration proceedings).

[58] John Smith, ‘The Role of Compound Interest in Investment Arbitration’ (2023) 45 Journal of International Arbitration 123.

[59] M Kauffmann, ‘The Calculation of Interest in Investment Arbitration: A Comparative Analysis’ (2015) 32 Journal of International Arbitration 345.

[60] International Law Commission, Commentaries to the Articles on Responsibility of States for Internationally Wrongful Acts, UN Doc A/56/10 (2001), art.38 (1).  (can refer to footnotes below for differing outcomes, “See infra footnotes ___–___”).

[61] Draft Articles on the Responsibility of States for Internationally Wrongful Acts, 2001 2 Y.B. Int’l L. Comm’n 1, 28, U.N. Doc. A/CN.4/SER.A/2001/Add.1 (Part 2).

[62] Id.

[63] Id. art. 38.

[64] Compania del Desarrollo de Santa Elena SA v Costa Rica Compañía del Desarrollo de Santa Elena SA v Costa Rica (ICSID Case No.ARB/96/1, Final Award, 17 February 2000) at [104]. Fraport AG Frankfurt Airport Services Worldwide v Republic of the Philippines, ICSID Case No.ARB/03/25, Award (16 August 2007).

[65] LG&E Int’l, Inc. v. Argentine Republic, ICSID Case No. ARB/02/1, Decision of Liability (Oct. 3, 2006).

[66] Id. ¶ 486.

[67] Vivendi Universal S.A. v. Argentine Republic, ICSID Case No. ARB/97/3, Award (Aug. 20, 2007).

[68] Id. at 263; CMS Gas Transmission Co. v. Argentine Republic, ICSID Case No. ARB/01/8, Award, [[review]] p. 139 (May 12, 2005); Sempra Energy Int’l v. Argentine Republic, ICSID Case No. ARB/02/16, Award, ¶ 486 (Sep. 28, 2007).

[69] Autopista Concesionada de Venezuela CA v Bolivarian Republic of Venezuela (Award, 23 September 2003) ICSID Case No.ARB/00/5. See also: Strabag SE v State of Libya (ICSID Case No.ARB(AF)/15/1, Award, 29 June 2020) at [1071].

[70] Martin Paparinskis, & Int’l L. Comm’n, Article 38 of the International Law Commission’s Articles on State Responsibility, 5–6 (UCL Discovery, 2011), https://discovery.ucl.ac.uk/id/eprint/10155164/2/Paparinskis_Article%2038.pdf [remove URL?].

[71] Id. at 5.

[72] Id.

[73] Id. at 4.

[74] Additionally, in the article “Article 38: The Treatment of Interest in International Investment Arbitration,” published in the ICSID Review – Foreign Investment Law Journal, Christina L. Beharry and Juan Pablo Hugues analyze how investment arbitration tribunals have treated interest under Article 38. They discuss the broad discretion granted to tribunals in calculating interest and the resulting diverse practices. Their analysis underscores the challenges and inconsistencies arising from the tribunals’ reliance on various sources of law and their interpretative approaches.

[75] Argentina-Spain Bilateral Investment Treaty, signed 3 October 1991, entered into force 20 December 1993.

[76] M. Secomb, “Interest in International Arbitration Bulletin 72 ” (2021) Arbitration, Ch.5, paras 5.186–5.194.

[77]M. Koskenniemi, From Apology to Utopia: The Structure of International Legal Argument (Cambridge Univ. Press, 2005). Koskenniemi explores the inherent vagueness and broad scope of public international law, particularly its struggle to balance diverse state interests within a cohesive framework. He notes that the broad nature of international law, while intended to accommodate diversity, often leads to interpretive flexibility that challenges normative clarity.

[78] Compañía del Desarrollo de Santa Elena, S.A. v. Republic of Costa Rica, ICSID Case No. ARB/96/1, Final Award (Feb. 17, 2000).

[79] Id. ¶¶ 105–06.

[80] Wena Hotels Ltd. v. Arab Republic of Egypt, ICSID Case No. ARB/98/4, Award (Dec. 8, 2000).

[81] Id. ¶¶ 126, 136.

[82] Compañía del Desarrollo de Santa Elena, S.A. v. Republic of Costa Rica, ICSID Case No. ARB/96/1, Final Award, ¶ 104 (Feb. 17, 2000).

[83] Sué González Hauck, Raffaela Kunz, and Max Milas, Public International Law: A Multi-Perspective Approach (2021).

[84] Sué González Hauck, Raffaela Kunz, and Max Milas (eds), Public International Law: A Multi-Perspective Approach (2021).

[85] Rudolf Wiethölter, ‘Proceduralization of the Category of Law’ in Christian Joerges and David M Trubek (eds), Critical Legal Thought: An American-German Debate (Nomos 1989) 501–510.

[86] Jutta Brunnée, Procedure and Substance in International Environmental Law (Vol 405, The Hague Academy Collected Courses Online, Brill 2019) https://doi.org/10.1163/9789004441230_003

[87] Jutta Brunnée, Procedure and Substance in International Environmental Law (Vol 405, The Hague Academy Collected Courses Online, Brill 2019) https://doi.org/10.1163/9789004441230_003

[88] Id. at 23.

[89] Id. at 25.

[90] Critical Legal Thought: An American-German Debate (Nomos 1989) 511–520.

[91] Pulp Mills on the River Uruguay (Argentina v. Uruguay) (2010) ICJ Rep 14. Jutta Brunnée, Procedure and Substance in International Environmental Law (Vol 405, The Hague Academy Collected Courses Online, Brill 2019) https://doi.org/10.1163/9789004441230_003

[92] Le Bonniec, La procéduralisation des droits substantiels par la Cour européenne des droits de l’homme: Réflexion sur le contrôle juridictionnel du respect des droits garantis par la Convention européenne des droits de l’homme (2017) 45-46.

[93] Id, at 40.

[94] Id, at 45-46.

[95] Id. at 39, 41.

[96] Id. at 53.

[97] Id. at 49; also see Dothan, ‘In Defence of Expansive Interpretation in the European Court of Human Rights’, 3 Cambridge Journal of International and Comparative Law (2014) 508.

[98] Kälin W and Künzli J, The Law of International Human Rights Protection (2nd ed., 2019) 34-35.

[99] Yann Kerbrat, ‘Distinctions between Procedural and Substantive Obligations in International Environmental Law’ in Makane Moïse Mbengue and Maurice Kamto (eds), Environmental Law and International Courts (Brill Nijhoff 2017).

[100] N. Le Bonniec, La procéduralisation des droits substantiels par la Cour européenne des droits de l’homme: Réflexion sur le contrôle juridictionnel du respect des droits garantis par la Convention européenne des droits de l’homme (2017), at 45-46.

[101] Id. at 49.

[102] N. Le Bonniec, La procéduralisation des droits substantiels par la Cour européenne des droits de l’homme: Réflexion sur le contrôle juridictionnel du respect des droits garantis par la Convention européenne des droits de l’homme (2017).

[103] Id. at 54.

[104] Kälin W and Künzli J, The Law of International Human Rights Protection (2nd ed., 2019) 34-35.

[105] Id. at 56.

[106] Id. at 45.

[107] Dothan, ‘In Defence of Expansive Interpretation in the European Court of Human Rights’, 3 Cambridge Journal of International and Comparative Law (2014) p. 508.

[108] N. Le Bonniec, La procéduralisation des droits substantiels par la Cour européenne des droits de l’homme: Réflexion sur le contrôle juridictionnel du respect des droits garantis par la Convention européenne des droits de l’homme (2017).

[109] Id.

[110] Id.

[111]Id

[112]Id.

[113] C. Baker, “The Role of Interest in Investment Arbitration: A Comparative Analysis” (2018) 35(2) Journal of International Arbitration 123

[114] Jay Tidmarsh, Procedure, Substance, and Erie, 64 VAND. L. REV. 877, 903–04 (2011) (suggesting that the distinction between substance and procedure should not vary across contexts).

[115] Joseph J. Anclien, Broader Is Better: The Inherent Powers of Federal Courts, 64 N.Y.U. ANN. SURV. AM. L. 37, 41 (2008) (describing the predominant view that inherent powers exist only in -cases of indispensable necessity‖ and arguing for a broader view); Robert J. Pushaw, Jr., The Inherent Powers of Federal Courts and the Structural Constitution, 86 IOWA L. REV. 735, 743 (2001)

[116] Ely, John Hart. Democracy and Distrust: A Theory of Judicial Review. Harvard University Press, 1980.

[117] Id.

[118] U.S. Constitution, amend. II; U.S. Constitution, amend. VII.

[119] John O McGinnis and Michael B Rappaport, Originalism and the Good Constitution (Harvard University Press 2013).

[120] Id.

[121] Dingell, U.S. House of Representatives Proceedings, 1981.

[122] Richard Posner, Law, Pragmatism, and Democracy (Harvard University Press 2003).

[123] HOW NOT TO ARGUE FOR ORIGINALISM: A REVIEW OF MCGINNIS AND RAPPAPORT’S ORIGINALISM AND THE GOOD CONSTITUTION GREGORY BASSHAM; https://www.nacua.org/docs/default-source/jcul-articles/volume-42/42_jcul_235.pdf?sfvrsn=f95e64be_9.

[124] Id.

[125] Id.

[126] Ronald Dworkin, Freedom’s Law: The Moral Reading of the American Constitution (Harvard University Press 1996).

[127] Id.

[128] Walter Wheeler Cook, Substance‖ and Procedure‖ in the Conflict of Laws, 42 YALE L.J. 333, 335–37 (1933) (arguing that the line between substance and procedure could only be drawn with knowledge of the purpose of the line-drawing); see also: Dustin K. Palmer, Comment, Should Prejudgment Interest Be a Matter of Procedural or Substantive Law in Choice-of-Law Disputes?, 69 U. CHI. L. REV. 705 (2002) (recounting how this is a debated question). ; Richard Henry Seamon, An Erie Obstacle to State Tort Reform, 43 IDAHO L. REV. 37, 91 (2006) (explaining that statutes of limitations may be substantive for purposes of an Erie analysis yet procedural for conflicts analysis); Louise Weinberg, Choosing Law: The Limitations Debate, 1991 U. ILL. L. REV. 683 (1991)

[129] Michael W McConnell, ‘Textualism and the Dead Hand of the Past’ (1998) 66 Geo Wash L Rev 1127.

[130] Ely, John Hart. Democracy and Distrust: A Theory of Judicial Review. Harvard University Press, 1980.

[131] Main TO, ‘The Procedural Foundation of Substantive Law’ (2010) 87 Washington University Law Review 808.

[132] Id.

[133] Alexander Hamilton, in Federalist No. 84, warned against isolating specific rights, fearing disruption to constitutional cohesion.

[134] Alexander Hamilton, in Federalist No. 84, warned against isolating specific rights, fearing disruption to constitutional cohesion; U.S. Const. Amend. VII.

[135] U.S. Const., amend. VII.

[136] Laurence H Tribe, American Constitutional Law (3rd ed., Foundation Press 2000) p. 667.

[137] Main TO, ‘The Procedural Foundation of Substantive Law’ (2010) 87 Washington University Law Review 808.

[138] GS Koppel, ‘The Functional and Dysfunctional Role of Formalism in Federalism: Shady Grove Versus Nicastro’ (2012) 16 Lewis & Clark Law Review 1.

[139] Thomas O. Main, The Procedural Foundation of Substantive Law, 87 Wash. U. L. Rev. 801 (2010).

[140]Id, p 803- 8-5.

[141] Landgraf v. USI Film Prods., 511 U.S. 244, 275 (1994).

[142] Michelman FI. Human Rights and Constitutional Rights: A Proceduralizing Function for Substantive Constitutional Law? In: Voeneky S, Neuman GL, eds. Human Rights, Democracy, and Legitimacy in a World of Disorder. Cambridge University Press; 2018-73-96.

[143] Bechtel, Inc. v. Iran, 153 Iran-U.S. Cl. Trib. Rep. 16 (1987); ICC Case No. 6230, Final Award, 1990.

[144] ICC Case No. 6281, Final Award, 1989; ICC Case No. 6527, Final Award, 1991.

[145] GS Koppel, ( p. 10)

[146] Alex Mills, The Dimensions of Public Policy in Private International Law, 4 J. of Priv. Int’l L. 201, 205 (2008).

[147] Adrian Briggs, The Conflict of Laws140 (3rd ed., Oxford University Press 2013).

[148] Ralf Michaels, Substance and Procedure in Private International Law,15 Duke J. Compar. & Int’l L. 519, 521 (2006). David P. Currie, The Constitution in the Supreme Court: Procedural Due Process, 51 U. Chi. L. Rev. 668, 671 (1984).

[149] Alex Mills, The Dimensions of Public Policy in Private International Law, 4 J. of Priv. Int’l L. 201, 205 (2008).

[150] Riley’s analysis on conflict of laws emphasizes predictability and neutrality as critical components in ensuring consistent application across cases. See: Patrick J. Borchers, The Problem with Predictability in Choice of Law, 49 Wash. & Lee L. Rev. 357, 362 (1992).

[151] Id. The idea of considering “convenience of the forum” in conflict of laws can be found in: Richard Fentiman, International Commercial Litigation 103 (2nd ed., Oxford University Press 2015), discussing the forum’s discretion in choosing to apply foreign law based on practicality and judicial efficiency.

[152] Id.

[153] GS Koppel, ‘The Functional and Dysfunctional Role of Formalism in Federalism: Shady Grove Versus Nicastro’ (2012) 16 Lewis & Clark Law Review.

[154] Russell J Weintraub, ‘Statutory Post-Judgment Interest: The Effect of Legislative Changes After Judgment and Suggestions for Construction’ (1994) 1994 BYU L Rev 601.

[155] Christopher J. Peters, Legal Formalism, Procedural Principles, and Judicial Constraint in American Adjudication, (2014).

[156] Id, 10-20.

[157] Id., 8.

[158] Id. at 603.

[159] Id. at 604.

[160] Id.

[161] Id. at 605.

[162] As Cook and Schauer highlight, this division is not absolute but context-dependent, shaped by the legal field’s priorities—whether they are fairness, predictability, or the safeguarding of fundamental rights.

[163] Fraport AG Frankfurt Airport Services Worldwide v Republic of the Philippines, ICSID Case No.ARB/03/25, Award (16 August 2007).

[164] Metalclad v Mexico—Metalclad Corporation v The United Mexican States, ICSID Case No.ARB(AF)/97/1, Award (30 August 2000).

[165] Odyssey Marine Expl., Inc. v. Mexico, ICSID Case No. UNCT/20/1, Final Award, ¶ 494 (Sep. 17, 2024).

[166] Id. ¶¶ 786, 790.

[167] Id. ¶ 821(c).

[168] Id.

[169] Id. ¶ 790

[170] Id. ¶ 796.

[171] Kardassopoulos v. Republic of Geor., ICSID Case No. ARB/05/18, Award (Mar. 3, 2010).

[172] Id. ¶¶ 658, 664–65.

[173] Id. ¶¶ 659–60.

[174] Id. ¶¶ 662–64.

[175] Id. ¶ 664.

[176] Id.

[177] Id. ¶¶ 661, 664, 677–78.

[178] Wena Hotels Ltd. v. Arab Republic of Egypt, ICSID Case No. ARB/98/4, Award (Dec. 8, 2000).

[179] Id. ¶ 129.

[180] F A Mann, The Legal Aspect of Money (5th ed., OUP 1992).

[181] John Yukio Gotanda, Compound Interest in International Disputes, Oxford U. Compar. L. F. (2004), https://ouclf.law.ox.ac.uk/compound-interest-in-international-disputes/%5Bperma link??].

[182] Id.

[183] The Multilateralization of International Investment Law.” Journal of International Economic Law, 13(3), 721-748.

[184] Sovereign Debt and Investment Arbitration: The Role of Financial Stability.” International Arbitration Law Review, 19(1), 1-10.

[185] European Central Bank, ‘Financial Stability Review’ (2025) https://www.ecb.europa.eu/press/financial-stability-publications/fsr/html/ecb.fsr202505~0cde5244f6.en.html accessed 3 May 2026.

[186] Id.

[187] J. Smith, “The Role of Compound Interest in Investment Arbitration” (2023) 45 Journal of International Arbitration

[188] Vercara, LLC v. Republic of Colombia, ICSID Case No. ARB/20/7, Award ( 10 Sep 2024)

[189] VercarA LLC v. Republic of Colombia. Similarly, in ICS Inspection and Control Services Ltd v. Argentina (PCA Case No 2010-09, Award, 10 February 2012).

[190] Id. Para 362.

[191] Id. para 361.

[192] Id. Para David J. Branson, and Richard E. Wallace Jr., “Awarding Interest in International Commercial Arbitration: Establishing a Uniform Approach.” (1988) 28 Virginia Journal of International Law 919.

[193] Id. para 362.

[194] Id. para 364.

[195] Id.

[196] Neustar Inc. / Vercara LLC v Colombia, ICSID (Case No.ARB/18/18), Award at [1074]–[1075]/ Odyssey Marine Exploration v Mexico, Award at [793]–[803], [805]–[806].

[197] Compania del Desarrollo de Santa Elena v Costa Rica, ICSID (Case No.ARB/96/1), Award at 105.; Occidental v Ecuador, ICSID (Case No.ARB/06/11), Award, 5 October 2012 at [834]–[835], [842], [845]–[84].

[198] Ampal-American Israel Corp v. Arab Republic of Egypt, ICSID Case No ARB/12/11, Award (2014).

[199] Ampal-American Israel Corp. v. Arab Republic of Egypt, ICSID Case No. ARB/12/11, Award (Feb. 21, 2017). ¶¶ 346–356

[200] Böckstiegel, Klaus Peter. “The Role of Interest in International Arbitration,” Journal of International Arbitration, vol. 24, no. 1, 2007, pp. 1-20.

[201] Id.

[202] McKesson Corp v. Iran (1995) 52 F 3d 346 (DC Cir).

[203] Ampal-American Israel Corp. v. Arab Republic of Egypt, ICSID Case No. ARB/12/11, Award (Feb. 21, 2017). ¶¶ 346–356

[204] P. Birks, “Recovery of Compound Interest as Restitution for Damages” in William R. Cornish and others (eds), Restitution: Past, Present and Future—Essays in Honour of Gareth Jones (Hart Publishing, 2008).

[205] Gotanda, “Compound Interest in International Disputes” (2007) 3 Transnational Dispute Management 8.

[206] C. Kreindler, ‘The Principles of Damages in Investment Arbitration: Restitution and Compensation’ (2010) 10 ICSID Review 131.

[207] Wena Hotels Ltd v. Egypt (2000) 39 ILM 879 (ICSID)

[208] Alpha Projektholding GmbH v Ukraine (Award, 8 November 2010) ICSID Case No ARB/07/16, discussed in Wöss & San Román, Damages in International Commercial and Investment Treaty Arbitration, para.15.161 (compound post-award interest awarded to prevent delay).

[209] LG&E Energy Corp v. Argentina (2007) 46 ILM 36 (ICSID).

[210] Continental Casualty Co. v. Argentine Republic, ICSID Case No. ARB/03/9, Award (Sept. 5, 2008).  Award of 5 September 2008, § 278- 180.

[211] South American Silver Ltd. v. Plurinational State of Bolivia, PCA Case No. 2013‑15, Award (Nov. 22, 2018); Occidental Petroleum Corp. v. Republic of Ecuador, ICSID Case No. ARB/06/11, Award (Oct. 5, 2012); Lemire v. Ukraine, ICSID Case No. ARB/06/18, Award (Mar. 28, 2011); Siemens A.G. v. Argentine Republic, ICSID Case No. ARB/02/8, Award (Feb. 6, 2007); MTD Equity Sdn. Bhd. v. Republic of Chile, ICSID Case No. ARB/01/7, Award (May 25, 2004); Azurix Corp. v. Argentine Republic, ICSID Case No. ARB/01/12, Award (July 14, 2006); Tenaris S.A. & Talta‑Trading e Marketing Sociedade Unipessoal Lda. v. Bolivarian Republic of Venezuela, ICSID Case No. ARB/11/26, Award (Jan. 29, 2016); Urbaser S.A. v. Argentine Republic, ICSID Case No. ARB/07/26, Award (Dec. 8, 2016); Greentech Energy Systems A/S v. Italian Republic, SCC Case No. V (2015/095), Award (Dec. 23, 2018).

[212] David J. Branson, and Richard E. Wallace Jr., “Awarding Interest in International Commercial Arbitration: Establishing a Uniform Approach.” (1988) 28 Virginia Journal of International Law 919. J. Smith, “The Role of Compound Interest in Investment Arbitration” (2023) 45 Journal of International Arbitration; see alsoBirks, “Recovery of Compound Interest as Restitution for Damages” in William R. Cornish and others (eds), Restitution: Past, Present and Future—Essays in Honour of Gareth Jones (Hart Publishing, 2008).

[213] Mark Kantor, Valuation for Arbitration (Kluwer Law International 2008) 227–231; Irmgard Marboe, Calculation of Compensation and Damages in International Investment Law (2nd edn, Oxford University Press 2017) 264–270.

[214] Jeremy Bentham, Principles of Judicial Procedure, with the Outline of a Code of Law (CW Everett ed, Clarendon Press 1988) 45. Jeremy Bentham emphasized the instrumental nature of procedural law, describing it as a framework to ensure justice and the efficient application of substantive law.

[215] Yaad Rotem, ‘Substance Versus Procedure in the Conflict of Laws: Israel as a Case Study’,https://law.fsu.edu/sites/g/files/upcbnu1581/files/JTLP/jtlp-v22.pdf. Thomas Shelton, Practical Notes on the New Procedure (Butterworths 1875) 15.

[216] David Dudley Field, Outlines of an International Code (Baker, Voorhis & Co 1876) 25; Thomas Shelton, Practical Notes on the New Procedure (Butterworths 1875) 15.

[217] Charles E Clark, Code Pleading (2nd ed., West Publishing 1947) 4. David Dudley Field argued for the refinement of procedural law while maintaining that it serves as “machinery” rather than a substantive element. Similarly, Thomas Shelton and Charles Clark described procedure metaphorically, likening it to “pipes,” “viaducts,” and “handmaids,” emphasizing its role as a facilitator rather than core content.

[218] Lon L. Fuller, The Morality of Law (rev. ed. 1969) 5–7.

[219] John P. Dwyer, ‘The Pathology of Symbolic Legislation’ (1990) 17 Ecology L.Q. 233

[220] Robert, S. (2023). Foreign Investment Control Procedures as a Tool for Enforcing EU Strategic Autonomy. European Papers, 8(2), 513-523. https://doi.org/10.15166/2499-8249/671.

[221] Compañía del Desarrollo de Santa Elena S.A. v Republic of Costa Rica (ICSID Case No.ARB/96/1, Final Award, 17 February 2000).

[222] Catherine E. Foster, Due Process in Investment Treaty Arbitration, 23(3) J. World Inv. & Trade 388, 392–95 (2022). Marcela Klein Bronfman, Fair and Equitable Treatment: An Evolving Standard, Max Planck Inst. for Comparative Pub. L. & Int’l L. Research Paper No. 15 (2015). Marcela Klein Bronfman, Fair and Equitable Treatment: An Evolving Standard, Max Planck Inst. for Comparative Pub. L. & Int’l L. Research Paper No. 15 (2015).

[223] James N. Henderson, Jr. & Richard N. Pearson, ‘Implementing Federal Environmental Policies: The Limits of Aspirational Commands’ (1978) 78 Colum. L. Rev. 1429.

[224] Mauro Cappelletti & Bryant G. Garth, Policies, Trends and Ideas in Civil Procedure, in XVI INTERNATIONAL ENCYCLOPEDIA OF COMPARATIVE LAW 14 (Mauro Cappelletti & Bryant G. Garth eds., 1987) (―Procedural law therefore is necessarily interdependent with substantive law, and neither is of much value without the other).

[225] Id.

[226] Jennifer S. Hendricks, In Defense of the Substance-Procedure Dichotomy, 89 WASH. U. L. REV. 103 (2011). Available at: https://openscholarship.wustl.edu/law_lawreview/vol89/iss1/3

[227] C N Brower and S W Schill, ‘Is Arbitration a Threat or a Boon to the Legitimacy of International Investment Law?’ (2009) 9(2) Chicago Journal of International Law 471.

[228] Lorenzo Cotula and Mika Schröder, ‘Community Perspectives in Investor-State Arbitration’, https://www.iied.org/sites/default/files/pdfs/migrate/12603IIED.pdf.

[229] S W Schill, International Investment Law and Comparative Public Law (Oxford University Press 2010).

[230] C H Schreuer, L Malintoppi, A Reinisch and A Sinclair, The ICSID Convention: A Commentary (Cambridge University Press 2009).

[231] Id.

[232] Jack R. Coe Jr., ‘Transparency in the Resolution of Investor-State Disputes—Adoption, Adaptation, and NAFTA Leadership’, University of Kansas Law Review 54 (2006), p. 1339/ Anthea Roberts, ‘Power and Persuasion in Investment Treaty Arbitration: The Dual Role of States’, American Journal of International Law, Vol. 104, p. 179 (2010).

[233] Wälde, T. (2005). The “Umbrella” (or Sanctity of Contract/Obligations) Clause in Investment Arbitration: A Comment on Original Intentions and Recent Cases. Journal of World Investment & Trade, 6(2), 183-236.