In considering the independent Italian city-republics Baldus elaborates a theory of the legal sovereignty of the city conceived as a whole, that is as a populus. His thesis of popular sovereignty is no general theory or blue-print, but is tailored to apply to this specific political context. Within the overall structure of the sovereign city-populus he is able to elaborate his theory of its membership, its form of government, and the limitations on its authority. Baldus, recognising that contemporary cities present a range of levels of jurisdiction from subordination to sovereignty, finds for all levels a place in his political theory; but his major contribution lies in his justification of the status of sovereign city-republics through developing and deepening the de facto argument, the result of his thorough-going acceptance of political reality. This is not to deny that Baldus admits for many cities a parallel structure of valid de iure jurisdictional rights derived from imperial or papal privilege or concession. Certainly any sovereignty enjoyed by a city is to some extent curtailed by Baldus' basic hierarchical view; yet the aspect of direct subordination to a superior contained in de iure concession means, as we shall see, that it is the de facto argument which produces the highest level of sovereignty of which cities are capable.