The Schengen area represents a textbook example of differentiation in the European Union. Not all EU member states are part of Schengen whilst others have opt-outs. At the same time, the common free movement area also embeds several non-EU states. Aside from the varied membership of the Schengen system, differentiation can also be observed in the internal rules that govern it. These rules, and particularly the option to reintroduce internal border controls, provide states with a failsafe option to return to national borders in high-pressure situations. As the paper argues, Schengen’s differentiated integration mechanisms, and the flexibility they provide, are part of its strength. They enable joint solutions to shared cross-border challenges in this highly sovereignty-sensitive area. However, there are risks attached to this flexibility as well. As recent crises highlight, an over-use of the system’s flexibility risks instilling fragmentation among states or can lead to situations where temporary controls become semi-permanent. Against this background, the paper proposes a set of three recommendations: (i) strengthening coordination mechanisms, (ii) strengthening common rules around the reintroduction of internal controls and (iii) promoting a stronger use of the Commission’s control and coordination competences.
1. The causes and nature of differentiated integration
2. Schengen under pressure – Overstretching flexibility
2.1 The Franco-Italian affair
2.2 Migration governance crisis of 2015–2016
2.3 The COVID-19 pandemic
3. Differentiation or disintegration? Concluding thoughts and recommendations