Equal Representation in Two-tier Voting Systems

The paper investigates how voting weights should be assigned to differ-ently sized constituencies of an assembly. The one-person, one-vote prin-ciple is interpreted as calling for a priori equal indirect influence on deci-sions. The latter are elements of a one-dimensional convex policy space and may result from strategic behavior consistent with the median voter theorem. Numerous artificial constituency configurations, the EU and the US are investigated by Monte-Carlo simulations. Penrose’s square root rule, which originally applies to preference-free dichotomous deci-sion environments and holds only under very specific conditions, comes close to ensuring equal representation. It is thus more robust than pre-viously suggested.