Abstract
Originally conceived as a technique of territorial organization of the unitary State, territorial decentralization produces effects on the whole unitary legal system. A tripartite dimension of decentralization (purpose, function, subject) leads to report on the evolution of the relationships between the State and local authorities. Territorial decentralization adapts the unitary legal system of State. First, on internal aspects, with a renewal of the theoritical conception of State with pluralism and new forms of States. Then, on external aspects with a renewal of local public action where local authorities adapt their operation in the face of external constraints more and more significant for the State and local authorities.