Who works with whom? Collaboration ties in legislative policy-making networks

Social relations have the potential to shape who assumes policy leadership positions in legislative politics. Applying a relational event modeling framework, this paper investigates if homophily and reciprocity predict patterns of collaboration between lawmakers as they negotiate proposed legislation. Specifically, it examines if members of the European Parliament (EP) who serve as rapporteurs or shadow rapporteurs are more likely to select into working with colleagues who share their personal attributes or with whom they have previously collaborated. It conceives of EP policy-making as an evolving two-mode network comprised of legislators and jointly produced policy documents as nodes, and (shadow-) rapporteurships as ties. Conditional logistic regression analyses confirm that previous collaboration, shared native language and gender, as well as policy expertise, increase the likelihood of MEPs becoming (shadow-)rapporteurs. In contrast, party loyalty shows no clear, unambiguous effect.