Are semi-presidential constitutions bad for democratic performance?

Many countries since 1990 have adopted semi-presidential constitutions, which are often considered to be problematic, primarily because of the potential for conflict between the assembly-supported government and the popularly elected president. Such conflicts are said to lead to unstable governments, policy paralysis and the eventual undermining of the democratic regime. Using data for all parliamentary and semi-presidential democracies between 1946 and 2006, we examine the effect of semi-presidential constitutions on the duration of prime ministers' tenure in office, government accountability with respect to economic outcomes, and democratic survival. We also examine (for a smaller sample of post-communist countries) the impact of these constitutions on the progress of structural reforms. We find that the observed higher instability of prime ministers in semi-presidential democracies is more due to the electoral system than to the presence of a popularly elected president. We also find that semi-presidential constitutions have little impact on the government's accountability to economic outcomes and on the survival of democratic regimes. Finally, we find that neither a weak president nor a weak government is optimal for the progress of economic reforms in post-communist countries. Regarding economic reforms, the optimal allocation of constitutional powers between the president and the government grants both significant powers.