International Investment Agreements in the Era of Transformation: Finding a Balance between Investor Protection and Regulatory Autonomy of States

The article provides a comprehensive analysis of the international legal foundations of international investment agreements (IIAs) using historical-legal and comparative-legal research methods. The author examines the evolution of foreign investment regulation from customary law norms to the modern system of treaty relations. The typology, functions, and regionally determined approaches to IIAs (European, North American, Asian, Latin American) are analyzed in detail. The territorial and temporal scope of application of agreements is investigated with emphasis on denunciation issues and sunset clauses. The key concepts of “investment” and “investor” are thoroughly examined, including objective criteria for investments in arbitration practice (the Salini test). Using specific cases (Vattenfall v. Ger-many (II), Joy Mining v. Egypt, Biwater Gauff v. Tanzania), the article demonstrates practical aspects of IIAs applica-tion. The research identifies the main problems of the international investment agreements system and analyzes cur-rent reform initiatives at UNCTAD and UNCITRAL platforms, as well as alternative national and regional approaches. The author concludes that a new balance between investor protection and states’ regulatory autonomy must be es-tablished. The article contributes to the understanding of contemporary challenges and development trends in inter-national investment law amid growing criticism of the existing IIAs system.