This book highlights the intersection between international investment law and sustainable development, particularly in the context of the right to regulate for public interest related to sustainable development. Addressing key challenges hindering the harmony between investment law and sustainable development, the book unveils a new methodology to assess whether a government measure or foreign investment contributes to sustainable development. The primary question driving this text is: how should investment treaty arbitration tribunals evaluate the sustainable development impact of both government measures and foreign investments affected by those measures? Beginning by establishing a conceptual framework around the right to regulate for public interest, the book also identifies limitations in the typical approach taken in investment treaty arbitration. Additionally, broader systemic constraints within international investment law concerning sustainable development are discussed. This book will be of interest to students and scholars in the field of international investment law, economic law, and sustainable development.