In this article, I offer a theory of lawmaking in multiparty presidential systems with different legislative institutions. I present a model that combines Krehbiel's pivotal politics theory with Tsebelis's veto players theory. This model simplifies various institutional veto players into the de facto veto players. I analyze the model to explain how the government type (unified versus divided governments), the legislative rules (majoritarian versus supermajoritarian rules), and the party system (two-party versus multiparty systems) affect legislative productivity. I apply the theoretical results obtained to solve the puzzle about the nondifferential legislative performance between unified and divided governments in the National Assembly. I test a hypothesis stating that the distance between the ideological positions of the agenda-setter and the de facto veto players has a negative effect on the proportion of controversial bills enacted between the 16th and the early 21st National Assemblies.

Relying on social choice theory, this paper argues that uncertainty regarding future public policies is likely to be related to party institutionalization and legislative organization. The argument is evaluated using survey data from businesses in eight EU member states in East Central Europe. It finds that firms report lower concern over policy uncertainty in systems with higher party institutionalization. There is also some evidence, although less robust, that restrictive parliamentary agenda control leads to lower perceptions of policy uncertainty and this effect mediates the influence of party institutionalization. These results tend to hold if one controls for the effect of other national and firm-level factors.