In broad terms, the investment of authority at the lowest possible level of an institutional hierarchy.
The origin of the principle of subsidiarity is in Catholic Social Theory (CST), although similar principles can be found in Calvinist thought. The purpose of subsidiarity in CST was, on the one hand, to limit the role of government as a whole in order to vindicate and protect the place of private institutions including the Church itself, while, on the other hand, justifying some role for government. This notion of subsidiarity was enmeshed in an understanding of society as an organism characterized by a hierarchy of organs. Subsequently subsidiarity has been used as a quasi-constitutional concept in some federal or federal-type political systems to provide a rationale for the allocation of powers between various levels of government. Wherever possible, powers are given to the least aggregated level of government; only when a particular task cannot be undertaken adequately by a ‘low’ level of government will it be handed ‘up’ to a higher level. It is this conception which is most useful in the analysis of German, Swiss, and European Union politics, which provide the empirical context for most discussion of subsidiarity. Controversy over subsidiarity in the EU has shown it to be an essentially contested concept. What to one person is of only local interest, to another is a matter of Union-wide concern. Transport of animals and working conditions are two examples. Although not inevitably incompatible with the CST definition, the use of the notion of subsidiarity in debates about federalism does not necessarily rest on an organic conception of society, as it focuses exclusively on the institutions of government.
— Daniel Wincott




