The article examines the limits, set out by the ECHR and European Union law, on the length of the detention of an alien subject to expulsion. First, it considers the guarantees elaborated by the case law of the Court of Strasbourg by interpreting Art. 5 (1) (f). The article highlights the absence of time limits on detention in the ECHR. Important limits on the length of detention, however, derive from the obligation to execute the removal arrangements with due diligence and from the obligation to release the migrant in the absence of a “realistic prospect of removal”. European Union law has implemented the guarantees established by the ECtHR in Directive 2008/115: the EU legal order permits the detention of aliens if removal arrangements are executed with due diligence and if a “reasonable prospect of removal” exists. In addition, Art. 15 of the Directive provides for maximum terms of detention (a period of six months extendable for a further period of twelve months). The article analyzes the issue of the possibility of a new detention period after the expiration of these time limits. Moreover, the article analyzes the procedural guarantees, paying particular attention to those provided for by the Directive in case of extension of the first detention period.
