The research engages with federalism’s oldest question: how to draw the vertical division of powers between the central authority and the states. Focusing mainly on socio-political factions over fundamental rights, the research’s overarching goal is to develop a theoretically grounded criteria to help determine which structural division of power may better suit resolving which type of faction. Specifically, the research confines its ambit to conflicts concerning minority rights—which pit majorities against minorities—and morally divisive rights, such as abortion—which splits majorities amongst themselves.

The analysis is carried out on two levels. First, on a normative and comparative level, the research reinstates federalism’s original principle of nemo judex in causa sua—no person ought to judge their own cause. This is to offer a theoretical account, revisiting James Madison’s theory on factions, impartiality, and the design of integrative polycentric/federal constitutions. In doing so, the research develops a comprehensive typology of the vertical division of powers and structural interactions on socially divisive issues in the US and EU. Through comparing minority rights, equal pay, and abortion cases on the two sides of the Atlantic, it provides a needed distinction to the underlying Madisonian theory in the Tenth Federalist.

Drawing on David Hume's work, the research finds that socio-political divisions over rights falls within the categories of principle-based and interest-based factions. Next, it establishes that polycentrism/federalism’s capacity to resolve conflict is optimised when interest-based factions are centralised. Contrariwise, principle-based factions are better placed in polycentricism’s fourth option which I term ‘mediated plurality’. It further offers analysis of the structural dynamics where the two factions overlap.

Secondly, on a prescriptive level, the research travels Eastward and utilises the ensuing theoretical findings to critically assess and reconstruct a century-old, yet incomplete, polycentric/supranational project in the Middle East. This is to demonstrate how a polycentric constitutional structure could better remedy factionalism in the region.