A confederation is a political union of sovereign states united for purposes of common action. Usually created by a treaty, confederations of states tend to be established for dealing with critical issues, such as defence, foreign relations, internal trade or currency, with the central government being required to provide support for all its members. Confederalism represents a main form of intergovernmentalism, defined as any form of interaction around states that takes place on the basis of sovereign independence or government.

Federalism is a mode of government that combines a general government with regional governments in a single political system, dividing the powers between the two. Johannes Althusius is considered the father of modern federalism along with Montesquieu. Althusius notably exposes the bases of this political philosophy in Politica Methodice Digesta, Atque Exemplis Sacris et Profanis Illustrata (1603). In the Spirit of the Laws, Montesquieu for his part sees examples of federalist republics in corporate societies, the polis bringing together villages, and the cities themselves forming confederations. Federalism in the modern era was first adopted in the unions of states during the Old Swiss Confederacy.