Les effets de la généralisation de la proportionnelle aux élections municipales : une parité incomplète au détriment de la participation

This note evaluates the effects of the 2013 reform that introduced proportional party-list voting with mandatory gender parity in French municipalities of 1,000 inhabitants and above, using a regression discontinuity design around that population threshold across the 2014 and 2020 elections. The findings reveal a clear trade-off: while the proportional list system mechanically increases the share of female candidates and elected councilors by 7 to 8 percentage points, it has no effect on the proportion of female mayors, only marginally boosts electoral competition (+0.1 candidate per seat on average), and -most strikingly -depresses voter turnout by 2 to 3 points in uncontested races while causing a dramatic surge in blank and spoiled ballots of up to 16 points, as voters accustomed to the flexibility of plurality voting are left with an all-or-nothing choice they cannot modulate. We conclude that the 2025 law, by extending this system to all French municipalities, is likely to amplify these democratic costs nationwide.