The hidden curse of French inter-communal power

In 2020, the issue of strengthening collaboration among French municipalities reached a turning point. As of January 2020, every municipality had to join one of the 1254 French inter-municipal structures. This milestone was accompanied by precise rules governing the distribution of seats among municipalities within the inter-municipal councils that govern each structure. However, the fairness of seat allocation among municipalities, according to the rules proposed by French law and based on the principles of proportionality, can be questioned. Since the pioneering works of Penrose (J R Stat Soc 109(1):53–57, 1946. https://doi.org/10.1111/j.2397-2335.1946.tb04638.x) and Banzhaf (Rutgers Law Rev 13(2):317–343, 1965), power index theory has shown that allocating representation to municipalities in proportion to their population tends to grant excessive power to the larger members. In this paper, we examine whether this phenomenon of imbalance can also be observed in France since 2020, using a new database that provides precise information on the number of seats allocated to each city. Even though we encounter significant variation across the country, our findings show that the current rules often result in over-representation of major cities. We also propose alternative allocation methods designed to mitigate these inequalities in representation.