According to the CJEU abstract:

K, a Pakistani national residing irregularly in Germany, was placed in detention in August 2020, for the purpose of deportation, in the Langenhagen section (Germany) of the penitentiary establishment in Hanover (Germany). This detention, initially limited until the end of September 2020, was extended, by decision of the Amtsgericht Hannover (district court of Hanover, Germany), until November 2020. The applicant, K, appealed  against that decision, and the latter court questions the legality of his detention in the light of the requirements imposed by Directive 2008/115. It pointed out that, during a certain period of the detention in question, the Langenhagen section received, in separate buildings, on the one hand, persons detained for the purpose of deportation and, on the other hand, common law prisoners. The same prison staff intervene there to take care of both convicted persons and persons held for the purpose of deportation. Furthermore, although this section has its own director, it is administratively attached to the Hanover prison establishment, which is placed, in its entirety, under the supervision of the Minister of Justice.

It was in the light of those circumstances that the District Court of Hanover decided to refer questions to the Court for a preliminary ruling relating to Directive 2008/115. The Court is asked to specify the conditions that a detention establishment must satisfy in order to be considered as a "specialized detention centre", suitable, in accordance with that directive, for the detention of third-country nationals awaiting deportation. The Court was further asked clarifications on the conditions and the judicial review required when a Member State, by way of derogation, detains these nationals in a prison establishment.

In the first place, as regards the concept of 'specialised detention centre' within the meaning of Article 16(1) of Directive 2008/115, the Court observes that the conditions of detention in such a centre must have certain specific features in relation to the conditions for the enforcement of custodial sentences in prisons. The detention of a third-country national for the purpose of removal is intended only to ensure the effectiveness of the return procedure and does not pursue any punitive purpose. Consequently, the conditions of detention in such a centre must be such that they avoid, as far as possible, detention being akin to confinement in a prison environment, suitable for detention for punitive purposes. In addition, both the rights guaranteed by the Charter of Fundamental Rights of the European Union ('the Charter') and the rights enshrined in Article 16(2) to (5) and Article 17 of Directive 2008/115 must be respected.

As regards the assessment of the place and conditions of detention in the present case, the Court states that it is for the referring court. That said, the Court states, inter alia, that the administrative attachment of a place of detention to an authority which also has powers over penitentiary establishments is not sufficient to exclude that it may be a 'specialised detention centre'. The same applies solely to the fact that a separate part of a complex in which third-country nationals are detained for the purpose of removal receives convicted persons, provided, inter alia, that separation is effectively guaranteed. In addition, the referring court must pay particular attention to the layout of the premises specifically dedicated to the detention of third-country nationals, to the rules specifying their conditions of detention and to the specific qualification and powers of the staff responsible for supervising detention and the establishment in which it takes place.

In the second place, the Court specifies the conditions under which a Member State may temporarily provide for the detention of third-country nationals, for the purpose of removal, in a prison, thus derogating from the principle of detention in a specialised centre.

First, such a derogation may be justified under Article 18(1) of Directive 2008/115, as long as the Member State concerned cannot reasonably be expected to put an end to the heavy and unforeseen burden, which continues to weigh on the capacity of its specialised detention centres, because of the exceptionally high number of third-country nationals subject to a decision ordering their detention for removal purposes. A periodic review of the situation may be necessary in this regard. Moreover, such detention in a prison is precluded if it proves incompatible with a possible situation of vulnerability of the third-country national concerned. In any event, it shall also be excluded where a place is available in one of the specialised detention centres of the Member State concerned or where a less coercive measure is possible. Finally, the conditions of detention must be distinguished, as far as possible, from the conditions of detention applicable to persons convicted of criminal offences.

Second, under the second sentence of Article 16(1) of Directive 2008/115, detention in a prison may, exceptionally, be justified by reason of a total, sudden and temporary saturation of all specialised detention centres in the Member State concerned, provided that the third-country national concerned is separated from ordinary prisoners and appears, clearly, that no less coercive measure is sufficient to ensure the effectiveness of its return procedure. Any detention in a penitentiary institution based on this provision may be ordered only for a short period of time and ceases to be justified when the saturation of specialised detention centres persists beyond a few days or is repeated systematically and at short intervals. Finally, the fundamental rights guaranteed by the Charter and the rights enshrined in Article 16(2) to (5) and Article 17 of Directive 2008/115 must be respected throughout the period of detention.

If the conditions of the abovementioned situations are not met and the national legislation concerned cannot be interpreted in accordance with EU law, the principle of the primacy of EU law requires the national court to disapply that legislation.

Finally, in the third place, the Court examines the extent of judicial review incumbent on a national court when it receives an application for detention, in a prison, of a third-country national for the purpose of removal, or an application for an extension of such detention, on the basis of Article 18 of Directive 2008/115. In the light of the right to effective judicial protection, guaranteed in Article 47 of the Charter, that court must be able to verify compliance with the conditions imposed by Article 18. For those purposes, it must, in particular, be able to rule on any relevant matter of fact and law, that power cannot be limited solely to the evidence submitted by the administrative authority concerned.