1. Exhaustive list of grounds As illustrated above, there is considerable diversity on how grounds for detention are reflected in national laws. While in general terms the different grounds reviewed can all be linked in one way or another to Article 5.1(f ) ECHR, the wording sometimes used does not necessarily imply that the deprivation of liberty is resorted to in order to prepare the return or implement removal. This is in particular the case when irregular entry or stay constitutes a ground for detention. FRA Opinion Grounds for pre-removal detention must be exhaustively listed in national legislation and defined in a clear manner. The simple fact of being an irregular migrant should never be considered as a sufficient ground for detention. 1.3. Grounds not covered by Article 5.1(f) ECHR Court of Justice of the European Union Kadzoev, 2009, paragraph 70 The possibility of detaining a person on grounds of public order and public safety cannot be based on Directive 2008/115 [the Return Directive]. The European Court of Human Rights (ECtHR) held that the lawfulness of detention also implies that the deprivation of liberty is in keeping with the purpose of the restrictions permissible under Article 5.1 of the Convention.39 Article 5.1(f ) ECHR allows for the deprivation of liberty of a person either to prevent his effecting an unauthorised entry into the country or against whom action is being taken with a view to deportation or extradition. Detention of nonnationals on other grounds, such as crime prevention, public health or vagrancy, is not admissible under this provision of the Convention. Stricter safeguards need to be fulfilled to justify detention on criminal grounds;40 whereas detention for reasons of public health is allowed only as a last resort for diseases, which spreading is dangerous for public health or safety.41 It should also be recalled that national security or public order are per se not sufficient to justify a deprivation of 39 ECtHR, Bouamar v. Belgium, No. 9106/80, 29 February 1988, at 50. 40 Article 5.1(a) requires a conviction by a competent court, whereas Article 5.1(c) on the arrest of a person suspected to have committed a crime in order to bring him/her before a court necessitates a ‘reasonableness’ test, which would require “the existence of some facts or information which would satisfy an objective observer that the person concerned may have committed the offence”, ECtHR, Fox, Campbell and Hartley v. the United Kingdom, Nos. 12244/86, 12245/86 and 12383/86, 30 August 1990, paragraph 32. 41 See ECtHR, Enhorn v. Sweden, No. 56529/00, 25 January 2005, paragraph 44. liberty, which, according to the Convention, has to be based on one of the exhaustive grounds foreseen in Article 5.1 and formulated in a clear manner. Similarly, the Return Directive only allows for detention of an irregular migrant in order to prepare the return and/ or in order to carry out the removal process. It provides two circumstances – risk of absconding and other actions by the person concerned which avoids or hampers the return or removal process – which illustrate when deprivation of liberty can be resorted to.42 In a number of countries, however, alien legislation is used as a basis to provide for the detention of thirdcountry nationals also for public health, public order or national security reasons or when there is a risk that the persons concerned may commit a crime. Based on a review of national legislative provisions accessible to the Agency, several countries contain in their immigration or aliens laws references to public health, public order or national security considerations. In a first group of countries, these considerations describe in greater detail circumstances in which detention for the purpose of removal is allowed. In the Czech Republic, aliens in return or removal proceedings can be detained in three different situations, including if there is a risk that the person might endanger the security of the state or might materially disrupt public order. This includes, for example, situations in which the foreigner might endanger state security by using violence for political aims or situations in which the foreigner endangers public health, due to his/her suffering from a serious disease.43 In Finland, an alien may be detained to prevent his/her entry or facilitate removal, if taking account of the alien’s personal and other circumstances, there are reasonable grounds to believe that he or she will commit an offence in Finland.44 In Greece, the provision on administrative expulsion allows detention of an alien considered dangerous for the public order.45 In Germany, detention can be applied in case of well-founded suspicion of terrorism, although only if the deprivation of liberty is necessary to ensure his/her removal.46 In Hungary, detention to secure expulsion is admissible in case the third-country national has seriously or repeatedly violated the code of conduct of the place of compulsory confinement.47 In a second group of countries, public health, public order or national security considerations seem to justify detention regardless of whether action is being taken 42 Return Directive, Article 15.1. 43 Act No. 326/1999 on the Residence of Foreign Nationals in the Territory of the Czech Republic; Section 124 (1). 44 Aliens Act, Section 121.1 read in conjunction with Section 118. 45 TCN Act at Article 76.3. 46 German Residence Act, Section 58a read in conjunction with Section 62(2)1a and 62(2). 47 TCN Act, Section 54.1(c). 19