Legitimizing ISDS: Can Third-Parties Advance Sustainability Interests?

The study of the uneasy interplay between investor-state dispute settlement (ISDS) and sustainable development has already caused a great deal of ink to flow. While there are some separate attempts to align international investment agreements (IIAs) with sustainable development goals, most IIAs cannot accommodate such objectives within their traditional frameworks. These tensions are especially evident when an investment tribunal is invited to decide on a dispute that ultimately produces long-term effects on societies. Amicus curiae and other forms of third-party participation can enhance sustainable development standards within international investment law, constituting one of the crucial procedural pillars between these two competing regimes. This article scrutinizes various forms of third-party participation in defending sustainable development standards in the context of existing transparency and accountability safeguards in investment arbitration. It explores the general legal standards and developments in judicial practice, the critical modifications of investment treaties and arbitration rules and assesses their impact on revitalizing third-party participation, primarily through amicus curiae briefs, to advance compliance with sustainable development standards.