We consider a paradigm for distributed control where not only the control is distributed, the design problem for the control laws is also. The framework is based upon sufficient local conditions for global stability of dynamic systems on graphs, where the interconnections are by means of physical variables which are either shared or conserved. In the case of linear systems these conditions take the form of Nyquist-like tests which must be satisfied by each system and its neighbours. Examples will include a non trivial application to power systems stability.