Detention of third-country nationals in return procedures by the authorities to remove the person concerned or not. Such grounds are clearly not foreseen in the Return Directive, nor are they covered by Article 5.1(f ) of the ECHR. In Latvia, for instance, the fact of being an irregular migrant is per se one of the grounds for detention. When courts are asked to decide on a possible extension of detention they have to consider a number of circumstances, including risk of criminal behaviour and threats to national security public order and safety.48 In Lithuania, an alien may be detained (i) in order to stop the spread of dangerous and especially dangerous communicable diseases; (ii) when the alien’s stay in the Republic of Lithuania constitutes a threat to public security, public policy or public health.49 In Malta, prohibited immigrants, against whom a removal order has been issued, shall be detained and may not be released by the Immigration Appeals Board if they could pose a threat to public security or public order.50 48 2007 Immigration Law, Section 51.1 and 54.1 (points 4 -7). 49 Aliens Act, Article 113.1 at (6) and (7). 50 Maltese Immigration Act, Articles 14.2 and 25A.11 (c). The Maltese Ministry for Justice and Home Affairs informed the FRA that if a removal order is issued detention is mandatory, as it is considered necessary in order to prevent the person from absconding. 20 FRA Opinion EU Member States should ensure that grounds for detention established at a national level do not extend beyond the exhaustive list of legitimate grounds foreseen in Article 5.1 ECHR. Deprivation of liberty based on crime prevention, public health considerations or vagrancy should be governed by the same rules, regardless of the legal status the person concerned has in the host country. These grounds should therefore not be regulated by aliens or immigration laws, but in other pieces of legislation. Otherwise, there is a risk that this will lead to the application of different standards based on the legal status of the person in the country.