Dynamics of formal and informal institutional change in the EU

The introductory article to this special issue pursues two main objectives, one empirical the other theoretical. First, we argue that in order to obtain more comprehensive explanation of European integration we need to make a distinction between scholarship on history-making integration - departing from the assumption that transfers of sovereignty are chiefly the result of formal interstate bargains at treaty-amending intergovernmental conferences (ICGs) - which dominates most of the analyses on European integration, and the often-neglected sphere of interregnum integration - connoting that transfers of sovereignty result from informal bargains among EU actors in-between treaty-amending IGCs. Secondly, we seek to explore the conditions under which (informal) interregnum integration is likely to occur and how it interlinks with (formal) history-making integration. For this purpose, we develop a theoretical framework - rational choice historical institutionalism (RCHI) - and deduce a set of hypotheses about formal and informal institutional change which will be subjected to exploratory empirical testing in the contributions to this special issue.