The paper explores the conditions under which institutional veto players such as upper houses can be influential in parliamentary and semi-presidential systems without being subject to substantial reform pressures themselves. We argue that institutions with equal absolute veto power differ systematically in their “restrictiveness”, i.e., in the extent to which they constrain the processes of legislation and cabinet formation. Based on a sample of 21 advanced democracies between 1955 and 2015, we argue that a newly created index of restrictiveness can help us to explain patterns of cabinet formation as well as constitutional reform. Using conditional logit analyses, we show that potential coalitions that control restrictive veto institutions are more likely to form, everything else being equal, whereas the same is not true for permissive veto institutions. We also show that restrictive veto institutions are more likely to be weakened or abolished, if their veto power is not "absorbed" due to consistently high levels of compositional congruence.

Steffen Ganghof is a professor of comparative politics at the Faculty of Economics and Social Sciences of the University of Potsdam, Germany. His research interests include political institutions, democratic theory and political economy. He is the author of The Politics of Income Taxation (ECPR Press, 2006). His articles have been published or are forthcoming in journals such as the British Journal of Political Science, Comparative Political Studies, the European Journal of Political Research, Political Studies as well as Politics, Philosophy and Economics. Before joining Potsdam University, he was assistant professor of comparative government at the University of Mannheim and research fellow at the Max Planck Institute for the Study of Societies in Cologne.