Playing the co-decision game?: Rules' changes and institutional adaptation at the LIBE committee

The introduction of co-decision has transformed the European Parliament (EP), changing the patterns of behaviour inside the institution, especially its committees. The entry into force of the Treaty of Lisbon extends the use of co-decision; thus, more EP committees will have to adapt to the new patterns of behaviour set out by the new decision-making rules. In order to understand how this process of adaptation occurs and what the consequences are, the present study examines the change in decision-making rules that occurred in the committee for civil liberties and justice and home affairs (LIBE) after 2005 as a precedent for future changes. Interviews and analyses of legislative texts indicate that adaptation to co-decision may occur very quickly but that its extent can be limited by forms of dual behaviour, when the coexistence of two decision-making rules oppose two different worldviews, introducing uncertainty inside committees and among external actors.