Voting and Information Aggregation in Parliamentary and Semi-Presidential Democracies

This paper investigates legislation in parliamentary and semi-presidential democracies where the legislature and the president have formal role in legislation. A proposed law is first voted in the legislature and if it passes, comes to the consideration of the president. I study two prevalent legislative procedures: (i) Single-round legislation where the president's action is final, (ii) Two-round legislation the president's approval enacts the law but after his veto proposal returns to the legislature for rediscussion. In this setup I examine power balance and the efficiency of information aggregation. For this I build a model of strategic voting with incomplete information and analyze different ideological profiles of the president and the homogenous legislature. The president seems powerless in two-round legislation but in equilibrium there are instances he can change the legislation result. Power struggle arises only when the legislature is modernist and the president is conservative. If the legislature is conservative and the president is modernist, the president has no impact on the outcome, but adversely affects informational efficiency. If they have the same ideological bias, the presidential institution is beneficial and the president's existence provides full information aggregation with finite legislature size in single-round legislation. Above results can be generalized to heterogeneous legislature with two types, except full information aggregation is never achieved.