Party Cohesion in European Legislatures: Cross-Country and Cross-Party Comparisons

Abstract

Most legislative studies based on roll-call voting analysis describe European parliamentary parties as highly unified actors. However, this unity in voting behavior does not mean that parliamentary parties are homogeneous entities: ‘pre-floor’ disagreements can be frequent, and MPs might display varying degrees of party loyalty. This paper views party agreement and party loyalty as two dimensions of cohesion, and investigates party cohesion across fifteen European national legislatures on the basis of the cross-national PARTIREP MP Survey. First, the paper shows that, while roll-call voting analyses give a picture of highly united parliamentary parties, these European parliamentary parties in fact vary quite a lot according to their degree of cohesion. Second, the paper investigates some of the factors that might explain these variations. On the one hand, the paper deals with the impact of electoral rules (electoral formula, ballot structure and candidate selection methods). On the other hand, the paper examines the role of ideology in determining the frequency of MP-party disagreement and MPs’ attitudes of (non)loyalty. These observations help to understand what produces parliamentary parties’ varying levels of agreement and loyalty and how institutional and sociological factors can affect distinctly each dimension of cohesion. In this way, the paper provides new insights into the study of legislative party dynamics.

Keywords: Party Cohesion Legislative Studies