Shaping Legislative Behavior: The Power of Institutional Design on Politicians’ Behavior

The institutional approach posits that political institutions have a significant influence on political behavior by creating incentives for certain actions while discouraging others (Powell and DiMaggio, 1991). This has also been argued in the context of personalism, a phenomenon in which individual politicians play a more central role in politics than their parties (Rahat and Sheafer, 2007). When institutional arrangements grant greater autonomy to legislators, they are encouraged to act independently of their party, seek personal visibility, and advance individual goals. Conversely, when institutions concentrate power at the party level and foster collegiality, legislators are more likely to align their behavior with the party interests. This paper examines whether parliamentary institutions indeed shape the behavioral strategies of Members of Parliament (MPs). More specifically, it investigates whether high levels of institutional personalism correlate with more personalized behavior among MPs, and whether institutional collegialism fosters cooperative, party-oriented conduct. MPs’ behavior is assessed across three dimensions: (1) party switching, (2) the use of individual parliamentary tools, and (3) dissent from the party line. The study employs a comparative analysis of cases representing highly personalized parliamentary institutions (Australia, Greece, and the United Kingdom) and highly collegial ones (Spain, Denmark, and Ireland), following the framework of Friedman and Zamir (2023). The paper argues that institutional design strongly shapes MPs’ strategic choices. In personalized parliaments, MPs are expected to exhibit higher rates of party switching, greater reliance on individual tools, and more frequent dissent from their party. In contrast, collegial parliaments are expected to foster cooperative, team-oriented behavior, with MPs demonstrating stronger alignment with party goals.