Political Parties and Institutional Design: Explaining Constitutional Choice in Latin America

The formulas for electing presidents and the rules determining the legislative powers of presidents are important variables for explaining the performance of presidential democracies. This article develops a strategic choice model to explain variations in these institutional features. Based on this model, it is proposed here that constitution makers are likely to opt for more-than-plurality rules of presidential elections when the number of parties necessary to pass constitutional changes increases. It is also proposed that the makers of constitutions are likely to strengthen the legislative powers of the president when the number of parties necessary to pass constitutional changes increases and when parties are decentralized. The argument is supported by a statistical analysis of the determinants of constitutional choice in Latin America.