When Congress Prevails: Veto Overrides and Legislative Fragmentation in Multiparty Legislatures

This study delves into the determinants of legislative overrides in multiparty legislatures, with a specific focus on the influence of partisan fragmentation within congress. Utilizing an original dataset spanning from 1995 to 2017, we examine the cases of Ecuador and Peru. Our argument posits that during lawmaking, a dispersed and fragmented party system prevents the president from anticipating the preferences of the congressional pivotal party. In such a scenario of incomplete information, the president's capacity to introduce selective incentives through vetoes is limited. In this way, the president is less likely to break the congressional majority supporting a bill. Consequently, the vetoed bill becomes less acceptable compared to the original statute. This, in turn, provides the congressional majority with increased incentives to uphold the original bill, elevating the likelihood of a legislative override. In alignment with this rationale, our findings indicate that an increase in the effective number of parties (ENP) has a positive and significant impact on the probability of a legislative override. Additionally, our evidence underscores a noteworthy contrast between the relatively high rate of legislative overrides in Latin America and findings for the US case.