Subsidiarity is emphasized in the Catechism, the social encyclicals of the popes and the teaching of the Fathers and Doctors.
This document strikes Catholics as deeply bizarre. We're used to self-important position papers from Curia functionaries, but this one is particularly incoherent.
Subsidiarity is an organizing principle that matters ought to be handled by the smallest, lowest or least centralized competent authority.
But apparently there are some loop holes
Subsidiarity is perhaps presently best known as a general principle of European Union law. According to this principle, the EU may only act (i.e. make laws) where action of individual countries is insufficient.
http://en.wikipedia.org/wiki/Subsidiarity