Introduction

The intersection of international investment law and environmental protection represents one of the most dynamic and challenging frontiers in contemporary international legal discourse. As the global community grapples with the unprecedented urgency of climate change, international investment arbitration finds itself at a critical juncture where traditional paradigms of investment protection must be reconciled with increasingly pressing environmental and climate imperatives. This special issue of our journal, International Investment Arbitration: Environmental Protection and Climate Change Issues, addresses these evolving dynamics. It examines how international investment arbitral tribunals have navigated the complex terrain where economic interests intersect with environmental protection and climate change considerations in recent cases, as well as proposes and explores approaches that could be adopted in the future to meet these emerging challenges.

The significance of this intersection has been profoundly amplified by the adoption of the Paris Agreement on Climate Change in 2015 (Paris Agreement), which established a global framework for limiting temperature rise and transitioning to sustainable development pathways. The Paris Agreement's emphasis on mobilising financial flows consistent with low greenhouse gas emissions and climate-resilient development has created new expectations for how international investment should align with climate objectives. Simultaneously, the United Nations' Sustainable Development Goals (SDGs) Agenda 2030 has reinforced the imperative to integrate environmental sustainability into all aspects of international economic relations, including foreign direct investment (FDI) and the legal frameworks that govern it.

The Evolution of International Investment Law in the Climate Change Era

Traditional international investment agreements (IIAs) were primarily designed to protect foreign investors from host state interference, with environmental considerations often relegated to peripheral exceptions or carve-outs. The foundational principles of fair and equitable treatment (FET), full protection and security, and protection against expropriation were crafted in an era when environmental protection was not yet recognised as a fundamental global imperative. As Dolzer and Schreuer observe in their seminal work on international investment law, early bilateral investment treaties (BITs) and multilateral agreements were primarily concerned with creating predictable legal frameworks for capital flows, with limited attention to the environmental consequences of such investments.[1]

However, the landscape of international investment law has undergone a profound transformation in recent decades. The recognition that environmental degradation poses existential threats to human civilisation has fundamentally altered the context in which investment protection operates. Climate change, in particular, has emerged as what scientists describe as a "planetary emergency," requiring unprecedented coordination and regulatory intervention across all sectors of the global economy. This reality has created tension between traditional investment protection standards and the regulatory measures that states must implement to address climate change and environmental degradation.

The jurisprudence of international investment tribunals reflects this evolving landscape, demonstrating what can be characterised as a distinctive shift from an almost exclusive focus on investment protection toward a more nuanced approach that increasingly recognises the legitimacy and importance of environmental protection measures. Earlier awards, such as those in Santa Elena v Costa Rica[2] and Tecmed v Mexico,[3] established precedents that heavily favoured investor protection, with environmental measures often viewed skeptically as potential disguises for discriminatory treatment or indirect expropriation.

However, more recent decisions signal a marked departure from this approach. The tribunal in Methanex Corp v United States[4] recognised that non-discriminatory regulatory measures designed to protect public welfare, including environmental protection, do not ordinarily constitute compensable expropriation. This principle was further developed in cases such as Chemtura Corp v Canada,[5] where the tribunal acknowledged the state's legitimate regulatory authority to protect human health and the environment, even when such measures adversely affect foreign investments.

Jurisdictional Challenges and the Justiciability of Environmental Claims

One of the most complex challenges facing international investment arbitration in the climate change era concerns jurisdictional questions about the justiciability of environmental and climate-related claims. Traditional investment arbitration was designed to address commercial disputes between investors and states, with clearly defined parameters regarding what constitutes an investment and what types of claims fall within tribunal jurisdiction. The integration of environmental and climate considerations into these frameworks raises fundamental questions about the scope and limits of investment arbitration.

The challenge is particularly acute when environmental harms extend beyond the immediate parties to a dispute, affecting broader communities, ecosystems, and global commons such as the atmosphere. Climate change, by its very nature, involves diffuse, long-term, and often irreversible impacts that may not align with the bilateral, compensation-focused framework of traditional investment arbitration. Some scholars, including Viñuales in his comprehensive analysis of foreign investment and the environment, argue that investment tribunals are ill-equipped to address polycentric environmental disputes that require consideration of multiple stakeholders and complex scientific evidence.[6]

Nevertheless, tribunals have increasingly been called upon to address environmental claims, either as defences to investment protection claims or as counterclaims by respondent states. The development of environmental counterclaims in investment arbitration represents a particularly significant evolution, allowing states to seek compensation for environmental damage caused by foreign investors. The Burlington Resources v Ecuador case exemplifies this trend, with Ecuador successfully pursuing environmental counterclaims that resulted in a substantial award for environmental remediation costs.[7]

The Influence of the Paris Agreement on Investment Arbitration

The Paris Agreement has fundamentally altered the legal and policy landscape in which international investment operates. Article 2.1(c) of the Agreement explicitly commits parties to "[m]aking finance flows consistent with a pathway towards low greenhouse gas emissions and climate-resilient development." This provision creates new legal expectations that may influence how tribunals interpret state regulatory measures related to climate change.

The Paris Agreement's emphasis on Nationally Determined Contributions (NDCs) provides states with legitimate policy justifications for implementing measures that may affect foreign investments, particularly in carbon-intensive sectors. As such, investment tribunals must now grapple with questions about how climate commitments under international law affect the interpretation of investment protection standards. The emerging doctrine of "sustainable development" interpretation, as articulated by Sands and other leading international lawyers, suggests that investment treaties should be interpreted in light of contemporary international law, including climate commitments.[8]

Furthermore, the Paris Agreement's provisions on international cooperation mechanisms, particularly Article 6, create new frameworks for carbon trading and offset mechanisms that may generate novel investment disputes. The development of international carbon markets under the Agreement's auspices introduces complex questions about the treatment of carbon credits as investments, the regulatory authority of states over carbon pricing mechanisms, and the interaction between climate policies and investment protection standards.

Recent Advisory Opinions and Their Impact on Investment Arbitration

The landscape of international climate law has been fundamentally transformed by a series of groundbreaking advisory opinions from major international tribunals. These opinions collectively establish a comprehensive framework of state obligations regarding climate change that has profound implications for international investment arbitration.

The ITLOS Advisory Opinion on Climate Change and Marine Environment

On 21 May 2024, the International Tribunal for the Law of the Sea (ITLOS) delivered its landmark Advisory Opinion on climate change and international law, marking the first time that an international tribunal had issued an advisory opinion on state obligations regarding climate change. The ITLOS opinion established that anthropogenic greenhouse gas emissions absorbed by the oceans constitute marine pollution due to their deleterious effects on the marine environment, including ocean acidification, ocean warming, and other harmful effects.

The ITLOS Advisory Opinion has particular relevance for investment arbitration involving marine resources, offshore energy projects, and coastal development. The tribunal confirmed that parties to the United Nations Convention on the Law of the Sea are obliged to take measures to combat marine pollution caused by climate change[9] , creating new legal obligations that may justify regulatory measures affecting foreign investments in marine sectors.[10] This finding provides a strong legal foundation for states defending climate-related regulatory measures against investor challenges, particularly in cases involving offshore oil and gas, marine renewable energy, or coastal infrastructure projects.

The ICJ Advisory Opinion on State Climate Obligations

The International Court of Justice (ICJ) delivered its Advisory Opinion on 23 July 2025, ruling that states have an obligation to protect the environment from greenhouse gas emissions and act with due diligence and cooperation to fulfil this obligation. The Court found that states are obligated to protect the climate system and other parts of the environment from anthropogenic GHG emissions, based on multiple legal sources, including the UN Charter, climate treaties (UNFCCC, Kyoto Protocol, and Paris Agreement), and customary international law.[11]

Crucially for investment arbitration, the opinion states that limiting global warming to 1.5°C should be considered the "primary temperature goal" for nations and, to achieve it, they are obliged to make "adequate contributions".[12] This establishes clear benchmarks against which state regulatory measures can be assessed, potentially providing stronger justification for climate policies that may adversely affect foreign investments. The ICJ's emphasis on due diligence obligations creates a legal framework that investment tribunals must consider when evaluating the reasonableness and necessity of climate-related regulatory measures.

The European Court of Human Rights' Climate Change Breakthrough

The European Court of Human Rights (ECtHR) delivered a watershed moment in climate jurisprudence with its Grand Chamber decision in Verein KlimaSeniorinnen Schweiz and Others v Switzerland on 9 April 2024.[13] This landmark judgment represents the first successful climate change case before the ECtHR and establishes crucial precedents that have profound implications for international investment arbitration.

The Court found that Switzerland had violated Article 8 (right to respect for private and family life) of the European Convention on Human Rights by failing to take adequate measures to combat climate change.[14] Crucially, the ECtHR established that Article 8 encompasses a right to effective protection by state authorities from the serious adverse effects of climate change on lives, health, well-being and quality of life.[15] The Court also found a violation of Article 6 § 1 (right to access to court) regarding the Swiss authorities' failure to provide adequate domestic remedies for climate-related claims.

Key Legal Findings with Investment Arbitration Implications:

The ECtHR determined that Switzerland had failed to comply with its positive obligations concerning climate change, identifying critical gaps in establishing a relevant domestic regulatory framework, including the absence of a carbon budget or national greenhouse gas emissions limitations.[16] The Court emphasised that while national authorities enjoy wide discretion concerning the implementation of legislation and measures, Switzerland had not acted "in time and in an appropriate way to devise, develop, and implement relevant legislation and measures."[17]

Implications for Investment Arbitration:

Enhanced State Police Powers: The ECtHR judgment significantly strengthens the legal foundation for states to defend climate regulatory measures in investment disputes. The finding that states have positive human rights obligations to protect against climate change creates a compelling justification for regulatory measures that may adversely affect foreign investments, particularly in carbon-intensive sectors.

Temporal Urgency Requirements: The Court's emphasis on acting "in time" establishes temporal parameters that may influence how investment tribunals assess the reasonableness of expedited regulatory timelines. This could provide states with stronger defences when implementing rapid transitions or emergency climate measures that affect investor expectations.

Carbon Budget Frameworks: The ECtHR's specific reference to the need for carbon budgets and national emissions limitations provides a concrete regulatory framework that states can implement to demonstrate compliance with human rights obligations. Such frameworks, when properly established, would likely receive deference from investment tribunals as bona fide regulatory measures.

Procedural Requirements: The judgment establishes procedural standards for adequate climate governance that may influence investment tribunals' assessment of whether regulatory measures meet due process requirements while serving legitimate policy objectives.

The ongoing supervision by the Committee of Ministers of the Council of Europe, which in March 2025 determined that Switzerland had not yet fully complied with the judgment requirements,[18] demonstrates the continuing legal pressure for enhanced climate action that will inform future regulatory measures affecting investments.

The Inter-American Court of Human Rights' Environmental Advisory Opinion

The Inter-American Court of Human Rights' advisory opinion on the environment and human rights[19] has established that states have positive obligations to protect individuals from environmental harm, including climate change impacts. This opinion reinforces the human rights dimensions of environmental protection, creating additional legal obligations that may justify regulatory measures affecting foreign investments. As the Inter-American Court of Human Rights develops its Advisory Opinion,[20] it is anticipated to further strengthen the human rights framework for environmental protection in the Americas.

Implications for International Investment Arbitration

These advisory opinions collectively create a robust legal framework that fundamentally alters the landscape for international investment arbitration. Several key implications emerge:

Enhanced Regulatory Justification: The advisory opinions provide states with stronger legal foundations for defending climate and environmental regulations against investment challenges. The clear articulation of state obligations under international law creates presumptions in favour of bona fide regulatory measures designed to meet these obligations.

Due Diligence Standards: The emphasis on due diligence obligations in both the ICJ and ITLOS opinions establishes procedural requirements that states must meet when implementing climate measures. This creates more predictable frameworks for investors while simultaneously legitimising necessary regulatory action.

Sectoral Implications: The ITLOS opinion's specific focus on marine pollution has particular relevance for investment disputes in offshore energy, shipping, fisheries, and coastal development sectors. Similarly, the ICJ's broader climate obligations affect all carbon-intensive investments.

Temporal Urgency: The advisory opinions' emphasis on the urgent need for climate action may influence how tribunals assess the reasonableness of regulatory timelines and the proportionality of measures that may affect investor expectations.

The Role of Human Rights in Environmental Investment Disputes

The growing recognition of the human rights dimensions of environmental protection has added another layer of complexity to international investment arbitration. The United Nations Human Rights Council's recognition of the right to a clean, healthy, and sustainable environment,[21] along with the work of Special Rapporteurs on human rights and the environment, has established clear linkages between environmental protection and fundamental human rights.

This development has significant implications for investment arbitration, as tribunals must increasingly consider how investment protection standards interact with states' human rights obligations. The Inter-American Court of Human Rights' advisory opinion on the environment and human rights, along with decisions such as those in Urgenda Foundation v State of the Netherlands,[22] have established that states have positive obligations to protect individuals from environmental harm, including climate change impacts.

Investment tribunals are beginning to grapple with these intersections, particularly in cases involving extractive industries or infrastructure projects with significant environmental impacts. The challenge lies in balancing investor protection with recognition of human rights obligations that may require states to impose strict environmental regulations or reject environmentally harmful projects altogether.

Institutional Innovation and Procedural Adaptations

The complexity of environmental and climate-related investment disputes has prompted significant institutional innovation within the international arbitration community. Leading arbitral institutions, including the International Centre for Settlement of Investment Disputes (ICSID), the London Court of International Arbitration (LCIA), and the International Chamber of Commerce (ICC), have developed specialised rules and procedures for addressing environmental aspects of investment disputes.

These innovations include enhanced provisions for expert testimony on scientific and technical matters, procedures for considering environmental impact assessments, and frameworks for addressing counterclaims related to environmental damage. ICSID's most recent set of arbitration rules, which came into effect in 2022, include specific provisions for the efficient handling of complex factual issues, including those involving environmental and scientific evidence.

Additionally, there has been growing interest in alternative dispute resolution mechanisms specifically designed for environmental and climate disputes. The Permanent Court of Arbitration's Environmental Dispute Resolution Services, established in collaboration with the United Nations Environment Programme, provides specialised procedures for addressing environmental disputes involving states and private parties. These developments suggest a recognition that traditional investment arbitration procedures may need adaptation to effectively address environmental and climate-related issues.

The Economics of Climate Regulation and Compensation

One of the most challenging aspects of environmental investment disputes concerns the economic assessment of regulatory measures and compensation for environmental damage. Traditional investment arbitration has relied heavily on financial valuation methods designed for commercial assets, but environmental assets and climate regulation present unique valuation challenges.

Climate regulations often involve long-term policy objectives that may not align with short-term investment returns, creating tension between investor expectations and regulatory necessity. The concept of "stranded assets" - investments that lose value due to climate transition risks - has become central to discussions about fair compensation in the context of climate regulation. Leading economists such as Stern and Carney have argued that the transition to a low-carbon economy will necessarily involve the stranding of significant carbon-intensive assets, raising questions about the extent to which investment protection should shield investors from transition risks.[23]

Furthermore, the economic assessment of environmental damage in investment arbitration requires consideration of complex valuation methodologies, including ecosystem services valuation, cost-benefit analysis of regulatory measures, and the social cost of carbon. These methodologies often involve significant uncertainty and value judgments that challenge traditional approaches to damages assessment in investment arbitration.

Future Directions and Emerging Trends

The trajectory of international investment law suggests that environmental and climate considerations will become increasingly central to investment dispute resolution. Several trends point toward this evolution: the proliferation of climate litigation globally, the integration of Environmental, Social, and Governance (ESG) criteria into investment decision-making, and the development of new generation IIAs that explicitly incorporate environmental and climate considerations.

Recent investment agreements, including the United States-Mexico-Canada Agreement (USMCA) and the European Union's new generation of investment agreements, include specific provisions addressing environmental protection and climate change. These agreements represent attempts to proactively address the intersection of investment protection and environmental regulation, though they still leave many questions unresolved.

The growing influence of ESG considerations in international finance is also reshaping the landscape of investment disputes. As investors increasingly incorporate climate and environmental risks into their investment decisions, the traditional bright-line distinction between commercial and environmental considerations becomes increasingly blurred. This trend suggests that future investment disputes will more frequently involve complex intersections of financial, environmental, and social considerations.

Concluding Remarks and Overview of This Special Issue

This special issue brings together leading scholars and practitioners to examine these complex intersections and emerging trends. The contributions address both theoretical frameworks and practical challenges, offering insights into how international investment law can evolve to address the realities of the climate era while maintaining its essential function of promoting international investment.

The urgency of climate change and environmental protection demands that the international legal community engage seriously with these challenges. As the contributions to this special issue demonstrate, the intersection of international investment law and environmental protection is not merely an academic exercise but a practical imperative that will shape the future of international economic relations. The development of legal frameworks that can effectively balance investment protection with environmental imperatives represents one of the most significant challenges facing international law in the twenty-first century.

Through rigorous analysis and thoughtful consideration of these complex issues, this special issue, which spans four volumes and includes the diverse perspectives of more than 60 authors from around the world, aims to contribute to the ongoing evolution of international investment law in a manner that serves both economic development and environmental protection objectives. The stakes could not be higher, and the need for legal innovation and adaptation has never been more pressing.

The first volume of this Special Issue focuses on the evolving nexus between international investment arbitration, environmental protection, and climate change issues. With climate change increasingly influencing the global legal and regulatory landscape, the volume explores how investment arbitration intersects with pressing environmental concerns, presenting a collection of insightful analyses by leading scholars and practitioners.

The opening article, Investment Treaties and Environmental Protection by Joaquin P. Terceño, Ewa Kondracka, and Tobias D. McKinnon, traces the evolution of environmental clauses in investment treaties since the 1990s. It categorises the various forms these provisions take, including exception clauses, procedural safeguards, and environmental harm clauses, while analysing how arbitral tribunals utilise the Vienna Convention on the Law of Treaties (VCLT) to interpret and integrate these provisions within broader treaty frameworks.

Gray Morfopoulos, in Environmental Protection Clauses in Investment Treaties, questions the necessity of explicit environmental carve-outs in investment treaties. While such provisions symbolise environmental commitments, Morfopoulos argues that arbitral tribunals have consistently upheld states' regulatory rights in environmental matters, even in the absence of such clauses, thus challenging their practical indispensability.

In Investor's Environmental Diligence in Investment Arbitration, Andreea I. Nica examines how tribunals assess the environmental diligence of investors. The article highlights how tribunals shape corporate behaviour by evaluating environmental responsibility during disputes, emphasising the importance of sustainable operations in transnational investments.

The fourth contribution, Trends in Environmental Jurisprudence and Climate Change Disputes by Annika Frosch and Wojciech Giemza, highlights a growing trend in arbitral decisions recognising environmental concerns. The authors discuss the challenges posed by climate-related disputes and predict an increased interplay between climate change law and investment arbitration in the years to come.

María José Monroy Valencia's article, Coexistence of Investment Arbitration and Environmental Law, tackles the fragmentation of international law and the conflicts between investment and environmental regimes. She explores mechanisms to harmonise these fields and enable sustainable environmental governance within investment arbitration frameworks.

In Environmental Law and Public Policy in Islam, Dr. Mahmoud Hussain and Nadia Ridwan Simpson delve into the UAE's legal system, which draws heavily on Sharia law, to examine how environmental protection aligns with public policy. The authors explore the arbitrability of environmental disputes under Islamic legal principles and the UAE's approach to sustainability.

Sudhanshu Swaroop and Paul Barker, in their article Paris Agreement, Energy Transition, and ISDS, focus on the intersection of international investment treaties and climate policies. They advocate for the modernisation of treaties like the Energy Charter Treaty (ECT) to align investment arbitration with the global transition to clean energy, encouraging capital flows into renewable energy projects.

Oliver Hailes, in Customary Duty and Energy Investment Arbitration, explores states' duties under customary international law to prevent environmental harm from unabated fossil fuel production. He examines how these duties influence treaty interpretation and investor expectations, particularly in energy-related disputes.

China's Perspective on Carbon Neutrality and Investment Protection, by Professor Tong Qi and Diwan Liu, examines how global environmental consciousness impacts China's investment treaties and foreign investment policies. The article emphasises the challenges of balancing investment protection with sustainability in a transitioning economy.

Erin Eckhoff, Sati Nagra, and Jack McNally's article, Contributory Negligence in Climate Investment Disputes, addresses whether investors can be held accountable for failing to anticipate climate-related risks. They explore how principles of contributory negligence could be applied in disputes where investors overlook environmental and regulatory challenges.

Kazim Berkay Arslan, in Precautionary Principle in Investment Arbitration, investigates the role of the precautionary principle in addressing environmental risks amidst scientific uncertainty. The article examines its implications for procedural and substantive aspects of disputes, including burden of proof and compensation.

Kendra Magraw's article, Institutional Practices for Sustainable Arbitration, shifts focus to the role of arbitral institutions in promoting sustainable practices. Magraw discusses how institutions can adopt innovative measures to reduce the environmental impact of arbitration while balancing stakeholder concerns and cost-effectiveness.

In Climate Action and Investment Protection, James Langley and Catherine Gilfedder reflect on the evolving standards of investment protection in light of climate change impacts. They explore how these developments may influence the interpretation and application of investment protections in future disputes.

William J. Simonsick, in Territoriality of Investment Agreements and Climate Change, examines how climate change challenges the territoriality principles of investment treaties. He advocates for new jurisdictional approaches to address the transboundary nature of climate change and its implications for treaty-based arbitration.

Finally, Prof. Dr. Maria Rosaria Mauro, in Investment Disputes and the Energy Charter Treaty, evaluates the ECT's role in climate-related disputes. She critically examines the modernisation efforts of the treaty and their potential to reconcile investment protections with the EU's environmental commitments, highlighting the challenges and opportunities of treaty reform.

The second volume of this Special Issue continues to delve into the dynamic interplay between international investment arbitration, environmental protection, and climate change, showcasing innovative legal thought and practical solutions to emerging challenges in this domain. The articles explore themes ranging from treaty reform and climate-centric policies to counterclaims and procedural developments, providing a nuanced understanding of how investment arbitration can align with global environmental goals.

The opening article, Navigating Investment Law in a Changing Climate, by Ben Sanderson and Lucia Bizikova, examines how states can balance their obligations under investment treaties with commitments to combat climate change. Using the Energy Charter Treaty modernisation as a case study, the authors propose a five-point action plan for states to minimise disputes arising from climate-related regulatory measures, emphasising proactive engagement with investors, treaty reform, and clear legislative frameworks.

In Simplifying the Pathway to 2030, Reg Fowler and Michael C.N.C.G. Putra advocate for increased protection for climate change-related investments. They argue that a Climate Change Investment Treaty focusing on carbon-critical countries is essential to bridge the energy transition investment gap and ensure the scale and pace needed to meet global climate targets.

Irene D. Valones, in Transnational Investment State Arbitration: A New Game-Changer for Global Climate Change Goals, explores the potential of transnational arbitration to reconcile state obligations for sustainable development with investor protections. She examines how reconfiguring FET provisions in IIAs can support climate change goals.

The fourth article, The Rise of Environmental Disputes: A Due Process-Based Approach to Evaluating Scientific Evidence by Joaquin P. Terceño, Campbell M.M. Herbert, and Pedro Ramirez, addresses the growing need for consistency in the treatment of scientific evidence in environmental disputes. The authors propose a due process-based framework to assess such evidence, drawing inspiration from Methanex v United States and other international jurisprudence.

Md Sekander Zulker Nayeen, in Politics of Investment Protection, explores the historical interplay between investment protection and environmental regulation. He traces the evolution of environmental clauses in IIAs and their increasing role in balancing state regulatory powers against investment protections, particularly in the context of sustainable development.

Addressing Climate Change through Non-Regression Clauses by Alexandros-Cătălin Bakos discusses the inclusion of non-regression clauses in investment treaties as a means to prevent states from diluting environmental protections. Bakos views this as part of a broader trend toward a regulatory paradigm that balances investor and environmental interests.

In How Are Investment Tribunals Going to Interpret 'Environmental Provisions' under New Generation Investment Agreements?, Shirin Sultana examines the environmental clauses in newer IIAs. She questions their effectiveness, given the lack of concluded arbitral decisions, and highlights the uncertainty surrounding their interpretation by tribunals.

Professor Tomoko Ishikawa, in Counterclaims Based on Corporate Climate Change Responsibility, discusses the role of counterclaims in addressing the distribution of climate mitigation burdens between states and investors. She emphasises the need for balanced frameworks to avoid unfair cost impositions on states while ensuring investor accountability.

Agata Zwolankiewicz, in Should Host-States Be Allowed to Make Counterclaims for Environmental Damage in Investment Disputes?, explores the legal basis for counterclaims in investment arbitration. Using cases like Perenco v Ecuador and Burlington v Ecuador, she evaluates how environmental counterclaims can balance the scales in investor-state disputes.

Finally, Are Counterclaims in Investment Treaty Arbitration an Effective Tool to Protect the Environment?, by Mayara Nunes Medeiros de Souza, examines jurisdictional and admissibility challenges for environmental counterclaims. She highlights the potential for such claims to enforce investor accountability, particularly under modern treaties with environmental provisions.

The third volume of this Special Issue continues its exploration of the critical intersections between investment law and environmental concerns. The collection of articles in this volume examines evolving practices, emerging challenges, and innovative approaches to align international investment arbitration with global climate goals.

The opening article, Mapping Climate-Related Investment Arbitrations, by Dr. Matteo Fermeglia, Catherine Higham, Korey Silverman-Roati, and Dr. Joana Setzer, presents an updated mapping of climate-related arbitrations under ISDS. The authors classify these cases and analyse their development, offering insights into the growing influence of climate concerns in investment disputes.

In Third-Party Funding in ISDS: Implications for Access to Justice in Environmental Disputes, Dr. Sai Ramani Garimella and Gautam Mohanty explore how third-party funding (TPF) facilitates access to justice, particularly for environmental disputes. The article discusses the regulatory challenges associated with TPF and advocates for transparency and disclosure mechanisms to ensure fairness and accountability.

Dr. Aikaterini Florou's article, Climate Change Arbitration: Using the Energy Charter Treaty to Enforce the New European Green Deal, examines the role of the ECT in promoting renewable energy investments under the EU Green Deal. It analyses the treaty's use in protecting legitimate expectations of investors in the renewable energy sector while addressing climate objectives.

In US and English Courts as the New Way to Circumvent the Ban on Intra-EU Arbitration, Dr. Delphine Defossez critiques the enforcement of arbitral awards in non-EU jurisdictions, such as the US and UK, despite the EU's ban on intra-EU arbitration. She highlights the tension between protecting investors and addressing environmental concerns within the evolving ISDS framework.

Olajide Akinleye-Martins, in A Review of Legal and Policy Compliance Measures of African Countries with the Commitments of the Paris Agreement, evaluates the challenges faced by African states in meeting their Paris Agreement obligations. The article underscores the socio-economic and political barriers to compliance and suggests tailored strategies for improved climate governance.

Alessandro Monti's article, Different Paths to the Same Goal? The Potential of BITs and FTAs for Achieving Climate Objectives, compares climate-related provisions in BITs and free trade agreements (FTAs). Monti highlights the fragmented nature of these agreements and their potential to align trade and investment law with climate action.

In Climate Change Considerations through the Environment Protection Lens in Investor-State Dispute Settlement (ISDS), Professor Dr. Rumana Islam and Mohammad Golam Sarwar address how ISDS tribunals handle climate change mitigation claims. The authors analyse the gaps in existing BITs and IIAs and explore the challenges faced by tribunals in integrating climate concerns into investment protection.

Hui (Helen) Pang, in The Role of International Investment Law in Climate Change Mitigation - A Theoretical Perspective, conceptualises renewable energy investments as global public goods. She critiques the state-centric focus of current investment law literature and advocates for broader inclusion of non-state actors in addressing climate change.

Dr. Okechukwu Ejims, in Developing a Climate-Resilient Investment Protocol: Lessons from the Final Draft Protocol on Investment to the Agreement Establishing the African Continental Free Trade Area, explores the potential for the AFCFTA Investment Protocol to integrate climate change objectives. The article emphasises the importance of accountability mechanisms for both states and investors.

Dr. Flavia Marisi's article, Counterclaims in ISDS: Refining the Balance between Economic Growth and Environmental Protection, examines the potential of environmental counterclaims to address damages caused by investments. Marisi analyses jurisdictional and admissibility challenges, offering insights into how tribunals can balance economic and environmental considerations.

Finally, States' Human Rights Counterclaims and Other Methods to Hold Investors Accountable for Their Human Rights Violations in Investment Treaty Arbitrations, by Heidi Yildiz, argues for broader acceptance of human rights and environmental counterclaims in investment arbitration. The article highlights the procedural and substantive barriers states face and proposes alternative methods for ensuring investor accountability.

The fourth volume of this Special Issue presents a multifaceted examination of the evolving relationship between international investment law, arbitration, and climate change, highlighting the challenges, prospects, and necessary reforms in this dynamic field.

Joseph M. Matthews reviews Thomas Lehmann's book, Investment Arbitration and International Climate Change Law: Revaluing Legitimate Expectations (published earlier this year) , which offers the first comprehensive analysis of how international climate law influences the legitimate expectations of foreign investors in the energy sector. This work aims to provide guidance to practitioners, arbitrators, policymakers, and treaty drafters dealing with net-zero-related disputes.

Khan Khalid Adnan's article explores the tensions between states' obligations to protect foreign investors and their duties to uphold human rights and environmental standards. Using the cases La Oroya v Peru and Renco v Peru (II) as focal points, the article examines how the doctrines of regime interaction and cross-fertilisation can shape substantive and procedural outcomes in investment dispute resolution.

Krystal Lee and Teresa Queirós critically assess the jurisdictional hurdles faced when raising environmental protection and climate change claims within investment arbitration. They highlight how treaty requirements concerning protected investments and the consent scope for counterclaims continue to act as significant barriers, even as environmental counterclaims become more frequent in other dispute forums.

Milcar Jeff Dorce addresses the conflict between the FET standard in international investment agreements and states' regulatory autonomy to pursue climate policies. Drawing on the "renewable energy saga" in Europe, the article critiques the overprotective interpretation of FET and advocates for recalibrating the standard to restore regulatory space and advance climate justice.

Peter Kayode Oniemola and colleagues analyse the implications of energy transition policies in petroleum-rich African states under international investment law. Emphasising the necessity of reform, the authors argue for a cautious approach to reforming oil and gas industries to mitigate exposure to arbitration risks while supporting climate commitments.

Dr. Seyed Nasrollah Ebrahimi and Dr. Youssef Ali examine transnational petroleum law (TPL) as a regulatory framework shaped by international energy contracts, arbitration awards, and principles of sustainability, human rights, and energy justice. Their study contends that TPL not only evolves from but also actively shapes these contracts, adapting to industry needs while fostering consistency in global energy transactions.

Stuart Bruce's article engages with increasing environmental disputes in investment arbitration, advocating for better integration of environmental considerations through refined treaty interpretation and applicable law principles. This approach aims to enhance investment arbitration's legitimacy and alignment with the rule of law.

Yağmur Gündoğdu highlights the urgent need to transform international investment law to align with climate objectives. Recognising the shortcomings of existing IIAs and ISDS mechanisms-originally designed with fossil fuel interests-the paper argues for their overhaul to incorporate climate-responsive provisions, emphasising tribunals' evolving role in interpreting climate-sensitive issues and advocating for IIAs as key tools within broader climate policy.

Finally, Dr. Seyed Nasrollah Ebrahimi, Sanaz Youssefi, Hamed Shakeri, and Ali Farahzad's paper examines the tensions in international investment arbitration resulting from states' climate policy actions that alter or terminate investment contracts. The authors analyse both procedural (jurisdiction, admissibility) and substantive (expropriation, compensation) challenges, focusing on the interplay between state police powers and investor rights under evolving treaties. By reviewing recent arbitral awards, new treaty provisions like sustainability and environmental carve-outs, and doctrinal debates, the study assesses when climate measures constitute compensable indirect expropriation and details difficulties in calculating damages, particularly for fossil fuels. The paper advocates for legal frameworks that balance urgent climate objectives with investor protections, offering guidance for policymakers and arbitrators navigating the energy transition and environmental accountability.