Voting and Information Aggregation in Unicameral 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 …rst 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 …nal, (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 e¢ ciency of information aggregation. For this I build a model of strategic voting with incomplete information and analyze di¤erent ideological pro…les 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 imPreprint submitted to Elsevier Science 21 April 2010 pact on the outcome, but adversely a¤ects informational e¢ ciency. If they have the same ideological bias, the presidential institution is bene…cial and the president’s existence provides full information aggregation with …nite legislature size in singleround legislation. Above results can be generalized to heterogeneous legislature with two types, except full information aggregation is never achieved. JEL Numbers: D72, D78