Anti-defection rules and party switching in the Italian Parliament

Abstract

Despite considerable progress in the study of party switching, scholarly interest in institutional constraints explicitly designed to limit or penalise inter-party mobility remains limited in the literature. This paper contributes to the emerging scholarship on party switching and legal institutional constrains by assessing the effectiveness of the new anti-defection regulations introduced in the Italian Senate starting from 2018. To evaluate the impact of this intervention, we develop two quasi-experimental research approaches that take advantage of the bicameral structure of the Italian Parliament and the fact that the anti-defection regulations were only implemented in the Senate and not in the Chamber of Deputies. Our results indicate that anti-defection regulations failed both to limit inter-party mobility and the formation of new legislative parties. However, they results effective in influencing the timing of party switching, concentrating it in the phases of government formation and dissolution.