The external dimension of EU justice and home affairs after the Lisbon Treaty::analysing the dynamics of expansion and diversification

The article introduces a research framework for analysing the external dimension of EU Justice and Home Affairs after the Lisbon Treaty. The dynamics of expansion and diversification, discernable for both the EU policy-making and the scholarly work dedicated to it, are at the centre of the article and constitute a common reference point for the present Special Issue. These dynamics have been triggered through deliberate decisions of involved policy-makers as well as through unintended spillover effects from other policy areas and/or decisions. The article also engages with the theoretically informed literature on the subject, which struggles with the definition of what this dimension actually constitutes, as well as how to best capture the practices of this field.We take stock of the scholarly debates by comparing the diverse approaches and discussing how much they complement each other and/or present different dimensions of a single ‘policy universe’.