Constitutional Rigidity Matters: A Veto Players Approach

Constitutional amendment rules have traditionally been considered the most important part of a constitution. Nevertheless, recent empirical analyses argue that constitutional amendment rules do not matter at all. This dispute is due to the misuse of independent and dependent variables and inappropriate methodology. Using the Veto Players approach to measure constitutional rigidity, this article proposes a new index covering ninety-four democratic countries. It starts by explaining the underlying logic of the veto players approach and describing the specific derivation of the rules for the construction of the rigidity index, which aggregates all institutional provisions in a logically consistent way. It then explains why the lack of constitutional rigidity is a necessary but not sufficient condition for significant constitutional amendments in democratic countries. Finally, the author creates a new dataset on the significance of constitutional amendments and estimates the appropriate (heteroskedastic) model, which corroborates the theoretical expectations and demonstrates that more significant amendments lead to a better fit.