World federalism or global federalism is a political ideology advocating a democratic, federal world government. A world federation would have authority on issues of global reach, while the members of such a federation would retain authority over local and national issues. The overall sovereignty over the world population would largely reside in the federal government. World federalism is distinguished from unitary world government models by the principle of subsidiarity, where decisions are made as much as possible at the most immediate level, preserving national agency to a large degree. Proponents maintain that a world federation offers a more effective and accountable global governance structure than the existing United Nations organization, while simultaneously allowing wide autonomy for continental, national, regional and local governments.