The State is organized under the principles of subsidiarity, local government autonomy, and democratic decentralization of the public service.
Although mainland Portugal has yet to implement a regional level tier, the autonomous regions of Madeira and the Azores have their own regional political and administrative statutes and self-governing institutions.
Until the end of the authoritarian regime (1926–1974), the administration of Portugal was highly centralized in the monarchy and, later, the republican governments.
Administratively, Portugal was divided into districts , municipalities and civil parishes , with only the last two having some political autonomy.
The current government structure is based on the 1976 Constitution, adopted after the 1975 Carnation Revolution.
In addition to defining the autonomous status of the Azores and Madeira (Articles 225-234), the Constitution specifically identifies the three tiers of government (Article 235-262): civil parishes, municipalities and administrative regions .
In addition, Law No.11/2003 (13 May 2003) allows the municipalities to organize themselves into inter-municipal communities , that can be of general or specific purposes; and metropolitan areas , that can be of two types: great metropolitan areas and urban communities .
The 1976 Constitution allows a high degree of freedom for the lower tier governments to decide their expenditures, but they are conditioned by state transferences to operate.
A referendum was conducted in 1998 in order to implement statutory and political regions with some degree of autonomy, but was rejected.
As a consequence of these constitutional revisions the "district" has been removed from the legal framework, but still remains an important and relevant division for other entities.
Similarly, it is still recognized by the general public. The 2011 bailout accord resulted in the proposed reduction of the number of municipal and parish local governments after July 2012, a condition of the $110 Billion accord.
In addition, the Portuguese territory was redefined during European integration, under a system of statistical regions and subregions known as Nomenclature of Territorial Units for Statistics.
These NUTS definitions, used for collecting statistical information, follow many of the countries border definitions. Although utilized by the Portuguese government, they do not have a legal status in law.