Application of the principle of legitimate expectation in the light of the decisions of the Constitutional Court and the Council of State

In this study, the principle of legitimate expectation, which has become one of the fundamental principles of administrative law, is examined in terms of its conceptual foundations, its applications in Turkish law, and its comparative dimensions within the framework of international law. In the first chapter, the definition of the principle, its legal basis, its relationship with related concepts, and its limits are analyzed; discussions in the doctrine and judicial precedents are included. In the second chapter, the interpretation of the principle in national law is explained in light of the decisions of the Constitutional Court and the Council of State; from an international law perspective, the development of the principle is addressed through the case law of the European Court of Human Rights, the Charter of Fundamental Rights of the European Union, and decisions of international investment arbitration. As a result, it has been determined that the principle of legitimate expectation is increasingly applied in Turkish law; however, it still lacks a clear normative basis, there is no consistency in judicial precedents, and its application remains limited in certain areas (particularly tax and social security). In this context, it is concluded that the principle should be legally defined, judicial decisions should be made consistent, and it should be developed in harmony with international standards.