Parliamentary norms

Parliamentary norms facilitate party group unity and are crucial for lawmaking and government stability. Previous studies on legislative norms have established the widespread prevalence of these norms, but have contributed little to understanding the determinants of role adoption. This study investigates whether and how party group leaders can foster these norms. Party group leaders have a strong interest in developing legislative norms, as they facilitate coordination and help ensure voting unity, thereby enhancing voting power. Drawing on survey data from parliamentarians across five legislatures (UK, Netherlands, Germany, Switzerland, European Parliament) and 80 elite interviews with group leaders and experts, the study examines the factors shaping the strength of legislative norms. Findings show a correlation between the disciplinary efforts of party group leaders and the extent of legislative norms, highlighting the role of leadership in shaping parliamentary behaviour.