Differentiated Integration in the EU - From the inside looking out. CEPS Paperbacks. January 2014

Flexibility might be convenient when it comes to accommodating member states’ differing socio-economic and political interests in an expanding EU. Yet, opt-outs, enhanced cooperation and cooperation between member states outside the EU’s legal framework are calling into question the boundaries of this constitutional, institutional and legal differentiation in an EU that is founded on common principles, with a specific legal order and common institutions.

The fall-out from the Brussels terrorist attacks. EPC Commentary, 16 June 2016

On 22 March, Belgium got a brutal wake-up call. In a coordinated attack, two nail bombs exploded in the departure hall of the Brussels National Airport. A little over an hour later, a third bomb exploded inside a metro train passing through Maelbeek station. 32 civilians lost their lives, while more than 300 people were injured. The Islamic State (IS) network, which was responsible for the Paris attacks on 13 November 2015, claimed responsibility. The arrest of Salah Abdeslam, the sole survivor of the Paris attacks, on 18 March, seems to have made IS expedite the Brussels attacks following a claim from the Paris prosecutor that Abdeslam would cooperate with the French Justice Department over the Paris attacks.