The Principle of Legitimate Expectations in Administrative Law: Development, Comparative Concepts, and Analysis for Thailand

Abstract

The principle of legitimate expectations constitutes a key mechanism in modern administrative law aimed at protecting the trust of individuals in the conduct of public authorities. This article examines the development and core substance of this principle through comparative legal analysis. In the German legal system, legitimate expectations are recognized as a general constitutional principle (Allgemeiner Rechtsgrundsatz) under the rule of law, closely tied to legal certainty and the principle of proportionality. In English law, the principle originated from procedural fairness and has evolved toward the substantive protection of individual interests through a balancing test with overriding public interests. Other jurisdictions—such as Australia, Canada, Poland, India, and France—have adopted varying approaches reflecting a shared objective: to constrain arbitrary state power and safeguard the public’s trust in administrative governance. In the Thai context, the Administrative Court has established interpretive guidelines in several landmark decisions. These include the recognition of substantive protection that upholds legal status even after administrative decisions are revoked, the weighing of individual expectations against public interests, and the linkage between legitimate expectations and the constitutional principle of the rule of law. Nonetheless, exceptions remain in cases involving gross negligence or concealment of material facts. Despite these developments, the application of the principle in Thailand remains inconsistent and underdeveloped. This article proposes a comprehensive framework for enhancing the protection of legitimate expectations in Thai administrative law. Recommendations include amending existing legislation to encompass a wider range of expectations, developing consistent judicial interpretive standards that cover both procedural and substantive dimensions, and establishing new institutional mechanisms—such as a dispute mediation committee—to promote fairness, transparency, and coherence in public administration in accordance with the rule of law.