The FET standard is one of the most important standards of protection in international investment law. Despite its widespread incorporation into investment treaties and extensive application in arbitral practice, disagreement persists regarding its normative foundation and the manner in which its elements can be coherently integrated. The principal question addressed in this study is: What is the normative foundation of the FET and how is this foundation reflected in the interpretation and application of its constituent elements? The study aims to identify the common normative foundation underlying these elements and to examine how considerations of justice and fairness are translated into applicable legal criteria, having regard to the limits of arbitral jurisdiction and the State’s right to regulate. The findings demonstrate that the constituent elements of FET including good faith, the prohibition of arbitrariness, transparency, the protection of legitimate expectations, proportionality, and procedural fairness, should not be regarded merely as a collection of separate and fragmented obligations. Rather, they can be understood in light of a common normative foundation and through recognized legal principles. Accordingly, justice and fairness are manifested through legal interpretation and objective criteria as applicable legal obligations, rather than as an autonomous source for creating new obligations. Consequently, the normative coherence of the standard can facilitate reconciliation between investment protection and the State’s public interests, provided that its application remains grounded in the treaty text, legal principles, the limits of arbitral jurisdiction, and the State’s right to regulate.