Understanding the Complexity of Party Instability in Parliaments

• In Event: Inter-Party Legislative Politics

Abstract

Elected representatives are widely expected to remain affiliated with the political parties that got them elected. However, party switching in parliaments is common, if not endemic, in many established and young democracies. By changing their affiliation, elected representatives create party instability: new parties form, existing parties dissolve, and the size of parties in parliament changes. Legislative party switching may have important effects on election and government formation outcomes, public policy and voter representation.

Yet, the legislative studies and party politics scholarship has not sufficiently examined the complexity of party instability created by legislative party switching. The well-established research on party switching has proposed insightful theoretical models that consider both politicians’ incentives to stay or leave their parties and the incentives for parties to keep or accept switchers (e.g., Desposato 2006; Heller and Mershon 2009). Empirical analyses generally focus on the costs and benefits of switching for individual legislators in terms of votes, office and policy, and have emphasised the role of political ambition as a key factor (Yoshinaka 2015). However, this research tradition tends to conceptualise party switching as the move of an individual legislator between two parliamentary groups. While this is certainly accurate in many instances, evidence suggests a much broader range of party instability in parliaments. This includes “collective defection” (coordinated switches from one parliamentary group to another), “fission-fusion” (coordinated moves from several groups to form a new parliamentary group), “entry” (an independent MP entering a parliamentary group) and “exit” (MPs exiting their parliamentary group to become independent MPs). Understanding these forms of party instability may require scholars to modify theoretical explanations based on the conceptualisation of switching as a move of an individual legislator between two parliamentary party groups. For example, the levels of discipline set by the party leadership is not relevant for “entry” switching, and “collective defection” may be driven by the factors that go beyond the cost-benefit calculus of an individual legislator.

Our goal in this paper is to shed light on under-researched forms of party switching by conceptualising and mapping out different forms of party instability in parliaments. We analyse the patterns of party switching in eight democracies (Estonia, Ireland, Italy, Lithuania, Norway, the Netherlands, Poland and Romania) from early 1990s to early 2020s, as well as in Denmark, France, Germany, Sweden and the United Kingdom beginning in Fall 2021. We measure the switches in three dimensions: (1) the magnitude (the number of MPs involved) and the coordination of moves (individual vs. collective switching), (2) the origin of switchers: unaffiliated MPs, from one or several parliamentary groups, and combinations thereof, (3) the destination of switchers: non-affiliated status, an existing or new parliamentary group, and combinations thereof.

In line with the state-of-the art research on legislative party switching, our empirical strategy is based on detailed records of party switching collected from the official information sources. We complement our quantitative datasets with qualitative data collection on the coordination of moves by individual legislators implemented as part of the research project “Party Instability in Parliaments (INSTAPARTY)”.

Using our new typology as a basis for examining a broader set of possible types of instability will allow us to provide a more complete empirical picture of parliamentary party instability than is provided in the current literature. We also expect that a deeper understanding of the complexity of this instability will provide new insights into both its causes as well as its effects on party support.

Authors

• Sona N. Golder, Penn State University

• Raimondas Ibenskas, University of Bergen

• Allan Sikk, University College London