The European Union, owing to its unique institutional structure, faces a major challenge when formulating foreign policies. On the one hand, the support of its Member States (MS) is essential in order to formulate common positions and coordinate foreign policies; to develop common policies (e.g. enlargement); and to advance integration in areas related to foreign policy (e.g. defence). On the other, the Commission, and with the coming into force of the Lisbon Treaty the European Parliament, have become significant actors that affect EFP through their agenda-setting and monitoring prerogatives.

Traditionally, European foreign policy was implemented through the interplay between the Union's three pillars. With the coming into force of the Lisbon Treaty on December 2009, this structure has been abolished, even if the divisions generated by the pillar structure will probably take some time to disappear. Bretherton and Vogler (2006), for example, have argued that actorness is different both in its nature and effects depending on the issue area examined. In particular, commercial policy is the domain of the Commission, which has the sole right of initiative, even though it is the Council and European Parliament that ratify agreements. This has not changed with the new treaty. Changes took place previously in the so-called ‘second pillar’, which included the intergovernmental Common Foreign and Security Policy (CFSP), and from 1998-1999 onwards, the European Security and Defence Policy (ESDP). Lisbon has renamed ESDP as the Common Security and Defence Policy (CSDP). The position of high representative created at the Cologne European Council of 1999 has mutated into a de facto foreign minister, currently Catherine Ashton. In the new European External Action Service (EEAS) in her domain, crisis management (previously in the second pillar) has been merged with related elements at the Commission (e.g. DG Relex) to avoid duplication. The rationale for this was that rivalries amongst the Commission and the Council were commonly assumed to be one of the main problems for the lack of coherence of European foreign policy. Indeed, several observers had identified the rivalry amongst the Council and the Commission as one of the key problems in the implementation of ESDP/CSDP (see: Korski/Gowan 2009).