Research on the Interpretation Competition and Normative Path of Fair and Equitable Treatment Clause from the Perspective of International Investment Arbitration

In the context of profound changes in the geopolitical landscape, many sovereign states have begun to resist the broad interpretation of the Fair and Equitable Treatment (FET) clause, in order to safeguard their regulatory measures in the field of climate governance and public policy. At the same time, emerging issues such as artificial intelligence (AI) and digital assets are challenging the traditional definition of investment under international investment law. Whether the host country's regulatory measures violate the reasonable expectations of investors has also generated long-term uncertainty. This paper uses the methods of literature analysis, comparative analysis and inductive analysis to sort out the international investment agreements and related arbitration practices, and analyzes the game of interpretation between national regulatory power and investor protection caused by vague provisions. On this basis, it further investigates how to achieve a reasonable balance between investor protection and national regulatory power through rule coordination. The study reveals that the open-ended formulation of the FET clauses is a structural characteristic of international investment law that adapts to the interests of different legal entities, and it is also an important reason for the long-standing differences in its interpretation. Based on this, this paper proposes a governance path from regional practice to multilateral rule coordination, and establishes a more stable and sustainable balance between rule certainty and interpretation diversity by improving the coordination mechanism.