The law and economics literature has traditionally paid very little attention to administrative law history and rules. Economic analysis of law, however, can provide a useful explanation of the logic of administrative law, beyond the purely legal top-down approach. On one side, administrative law provides public bodies with all the needed powers and prerogatives to face and overcome different types of market failures. On the other side, administrative law is a typical regulatory device aiming to face some structural and functional distortions of bureaucracy, as a multi-principal agent. From this economic (and political) point of view, administrative law is much less stable than what it is usually thought to be. Frequent changes in both substantive and procedural rules can be explained as the outcome of repeated interactions among the legislator, the bureaucrats and the private stakeholders.