The veto players theory can be used to analyze all political systems regard
less of regime ( presidential or parliamentary), party system (one-, two-,
or multiparty), and type of parliament (unicameral or multicameral). This p
aper develops the veto players theory to account for a series of important
political phenomena: the difference between majoritarian and supermajoritar
ian institutions; the importance ob absenteeism, or of political marginaliz
ation; the importance of agenda control and referendums; the reasons for go
vernment stability (parliamentary systems) and regime stability (presidenti
al systems); the reasons for independence of bureaucracies, and judicial in
dependence. All these phenomena are analyzed in a coherent way, on the basi
s of the same framework. Empirical evidence from existing literature corrob
orating the theory is provided.