A parliament beyond borders? Parties, nationality, and cooperation in the European Parliament

The European Parliament is a unique institution among parliaments worldwide and among the other institutions that make up the European Union. One question that is key to various bodies of scholarly work is that of how legislators cooperate within parties, party groups, and national delegations. Depending on the research focus, either the former two or rather the latter are found to be more important. This puzzling and seemingly contradictory finding is the starting point of this dissertation. By analysing virtually all forms of cooperation in the use of the main parliamentary instruments (roll-call voting, amendments, motions, parliamentary and agenda-setting questions), the author finds that the factors that influence cooperation decisions by legislators depend strongly on the type of parliamentary instrument, the time period, and the policy issue. This finding has consequences for our understanding of the role of the European Parliament, both internally as well as in relation to other (EU) institutions.