Proportionality Test in International Investment Agreements: Balancing Regulatory Sovereignty and Investor Protection
Main Article Content
Abstract
This study analyzes the jurisdictional clash between investor protection and host state regulatory sovereignty within modern international investment agreements. While new generation treaties incorporate explicit right to regulate provisions, arbitral tribunals frequently undermine these reforms through orthodox interpretations, creating a systemic arbitral backlash. Employing a normative legal methodology with statutory, conceptual, and case approaches, this research investigates the urgency of integrating the proportionality test into investor state dispute settlement. The systemic integration principle from the Vienna Convention on the Law of Treaties legitimizes this methodological transplantation. Results indicate that adopting proportionality as a mandatory standard of review effectively limits arbitral overreach, converting the conditional defenses of the state into inherent police powers. Contextualized within the new Model Bilateral Investment Treaty of Indonesia, this structural adaptation proves empirically vital. Ultimately, aligning national textual reforms with supranational proportionality analysis provides an equitable framework, successfully harmonizing absolute investment protections with public welfare mandates.
Downloads
Article Details
Section

This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
How to Cite
References
Aaken, Anne van. “Investment Law in the Twenty-First Century: Things Will Have to Change in Order to Remain the Same.” Journal of International Economic Law 26, no. 1 (March 9, 2023): 166–76. https://doi.org/10.1093/jiel/jgac054.
Alschner, Wolfgang. Investment Arbitration and State-Driven Reform. Oxford University Press, 2022. https://doi.org/10.1093/oso/9780197644386.001.0001.
Brabandere, Eric De, and Paula Baldini Miranda da Cruz. “The Role of Proportionality in International Investment Law and Arbitration: A System-Specific Perspective.” Nordic Journal of International Law 89, no. 3–4 (November 12, 2020): 471–91. https://doi.org/10.1163/15718107-89030012.
Gazzini, Tarcisio. “The Right to Regulate in International Investment Law.” In Routledge Handbook on International Economic Law, 383–401. London: Routledge, 2025. https://doi.org/10.4324/9781003399711-28.
Hailes, Oliver. “Environmental Clauses in Investment Arbitration: Deep Roots, Green Shoots and Dead Wood.” ICSID Review 40, no. 2 (January 13, 2026): 399–440. https://doi.org/10.1093/icsidreview/siaf003.
Hamamoto, Shotaro. “Aikaterini Titi, The Right to Regulate in International Investment Law.” In Permutations of Responsibility in International Law, 835–38. Brill | Nijhoff, 2016. https://doi.org/10.1007/978-3-319-29215-1_40.
Henckels, Caroline. “General and Security Exceptions and the Question of Compensation in International Investment Law.” Journal of International Economic Law 28, no. 1 (April 8, 2025): 63–77. https://doi.org/10.1093/jiel/jgaf005.
International Institute for Sustainable Development. “Philip Morris Brands Sàrl, Philip Morris Products S.A. and Abal Hermanos S.A. v. Oriental Republic of Uruguay, ICSID Case No. ARB/10/7.” International Institute for Sustainable Development, 2018. https://www.iisd.org/itn/2018/10/18/philip-morris-v-uruguay/.
Kingsbury, Benedict, and Stephan W. Schill. “Public Law Concepts to Balance Investors’ Rights with State Regulatory Actions in the Public Interest—the Concept of Proportionality.” In International Investment Law and Comparative Public Law, 75–104. Oxford University Press, 2010. https://doi.org/10.1093/acprof:oso/9780199589104.003.0003.
Kriebaum, Ursula, Christoph Schreuer, and Rudolf Dolzer. Principles of International Investment Law. Oxford University Press, 2022. https://doi.org/10.1093/law/9780192857804.001.0001.
Kuzhatov, Bagdat G. “The Energy Charter Treaty Reform: Why and How to Reach a Consensus on Fair and Equitable Treatment?” Energy Policy 163 (April 2022): 112769. https://doi.org/10.1016/j.enpol.2021.112769.
Lévesque, Céline. “The Inclusion of GATT Article XX Exceptions in IIAs: A Potentially Risky Policy.” In Prospects in International Investment Law and Policy, 363–70. Cambridge University Press, 2013. https://doi.org/10.1017/CBO9781139565479.029.
Mariani Agnestasia Soeitoe, Zaenal Arifin, Wijayono Hadi Sukrisno, Putri Haliza, and Ni Nyoman Tri Partini. “Adaptabilitas Arbitrase Internasional Dalam Sengketa Investasi: Studi Indonesia Dan Singapura.” Journal Juridisch 4, no. 1 (March 3, 2026): 93–109. https://doi.org/10.26623/jj.v4i1.13406.
McLachlan KC, Campbell. The Principle of Systemic Integration in International Law. Oxford University Press, 2024. https://doi.org/10.1093/law/9780192893741.001.0001.
Methanex Corporation v United States of America, UNCITRAL (Final Award on Jurisdiction and Merits) Part IV, Chapter D, para 7. (2025). https://www.italaw.com/sites/default/files/case-documents/ita0529.pdf.
Miles, Kate. The Origins of International Investment Law. Cambridge University Press, 2013. https://doi.org/10.1017/CBO9781139600279.
Price, David. “Indonesia’s Bold Strategy on Bilateral Investment Treaties: Seeking an Equitable Climate for Investment?” Asian Journal of International Law 7, no. 1 (January 11, 2017): 124–51. https://doi.org/10.1017/S2044251315000247.
Qian, Xu. “Revisiting Proportionality in Investment Arbitration: Theory, Methodology, and Interpretation.” Chinese Journal of International Law 21, no. 3 (December 15, 2022): 547–87. https://doi.org/10.1093/chinesejil/jmac020.
Qurbani, Indah Dwi, and Ilham Dwi Rafiqi. “Ecological Justice and Energy Transition Policy in Indonesia.” Jurnal Pembangunan Dan Alam Lestari 16, no. 2 (October 24, 2025): 89–94. https://doi.org/10.21776/ub.jpal.2025.016.02.03.
Schill, Stephan, and Christian Tams, eds. International Investment Protection and Constitutional Law. Edward Elgar Publishing, 2022. https://doi.org/10.4337/9781839100420.
Simbolon, Putu George Matthew, and Oktavani Yenny. “The Chilling Effect of International Investment Law and Indonesia’s Preventive Steps to Overcome It.” Jurnal Kajian Pembaruan Hukum 5, no. 1 (June 20, 2025): 91–122. https://doi.org/10.19184/jkph.v5i1.53690.
Sornarajah, M. The International Law on Foreign Investment. 5th ed. Cambridge: Cambridge University Press, 2021. https://doi.org/10.1017/9781316459959.
Szostak, Aleksander. “Towards Right to Regulate for Climate Actions: A Closer Look at the Modernized Energy Charter Treaty.” The Journal of World Investment & Trade, August 22, 2025, 1–29. https://doi.org/10.1163/22119000-12340382.
Tienhaara, Kyla. “Regulatory Chill in a Warming World: The Threat to Climate Policy Posed by Investor-State Dispute Settlement.” Transnational Environmental Law 7, no. 2 (July 22, 2018): 229–50. https://doi.org/10.1017/S2047102517000309.
Titi, Catharine. “The Right to Regulate in International Investment Law (Revisited).” Courses of the Summer School on Public International Law 18 (March 14, 2022). https://doi.org/10.65556/MYOE1036.
United Nations Conference on Trade and Development. “International Investment Agreements Navigator: Indonesia.” United Nations Conference on Trade and Development, 2026. https://investmentpolicy.unctad.org/international-investment-agreements/countries/97/indonesia.
———. “Investment Policy Framework for Sustainable Development,” 2015. https://unctad.org/system/files/official-document/diaepcb2015d5_en.pdf.
———. “The Reform of International Investment Agreements – State of Play.” United Nations Conference on Trade and Development, 2023. https://unctad.org/system/files/official-document/diaepcbinf2023d5_en.pdf.
United Nations Framework Convention on Climate Change. “The Paris Agreement.” United Nations Framework Convention on Climate Change, 2026. https://unfccc.int/process-and-meetings/the-paris-agreement.
World Trade Organization. “WTO Rules and Environmental Policies: GATT Exceptions.” World Trade Organization, 2026. https://www.wto.org/english/tratop_e/envir_e/envt_rules_exceptions_e.htm.
Zugliani, Niccolò. “A Role for Precedent in the Determination of the Standard of Review Applicable by Investment Arbitral Tribunals? A Case Study of Ect-Based Energy Disputes Against Spain.” The Italian Review of International and Comparative Law, December 19, 2022, 1–20. https://doi.org/10.1163/27725650-02020008.