Why Union Law Can And Should Protect Stateless Persons 129 objectives, and if no Treaty provision specifically creates a legislative competence to attain that objective, Article 352 TFEU can be used. We feel, however, that it is unnecessary (and therefore legally objectionable) to rely on Art. 352 TFEU, because Art. 79 TFEU already provides the necessary powers. For the purposes of developing a common immigration policy, paragraph 2(a) contains the legal basis for defining the conditions of entry and residence of third-country nationals. Paragraph 2(b) is the legal basis for defining the rights of persons who reside legally as third-country national in a Member State. It follows from Art. 67(2) that both paragraphs apply to stateless persons as well. There is nothing in the text of Art. 79(2)(a) which precludes defining the circumstances under which statelessness per se is a ground for residence. The fact of being stateless may, just as the fact of being a third-country national student having been accepted at a European university, the fact of being a third-country national with a work contract with a European employer and meeting a certain salary threshold, or the fact of being a third-country national with a hosting agreement with a European research institute—all categories which are not specifically mentioned in Art. 79 TFEU but do benefit from EU legislative action—be formulated as a ground for residence in Union law. Art. 79 TFEU does not in any way exclude certain motives for granting residence from its scope. On the contrary, its very aim is to harmonize these motives. Article 79 TFEU must also be considered to make the EU competent to establish common standards on statelessness determination procedures. If protection takes the form of a residence status on the grounds of statelessness, the mechanism for establishing statelessness is obviously essential for access to this status and the competence to set rules in that respect is therefore inherent in Art. 79(2)(a). Other directives adopted on the basis of Article 79 TFEU, such as the Students Directive (2004/114/EC), the Family Reunification Directive (2003/86/EC), and the Long-Term Residence Directive (2003/109/EC) also contain extensive rules on the procedural framework for determining whether the conditions for residence are met. 5.3 Subsidiarity The subsidiarity principle sets out that the EU should only act if the objectives of the proposed action cannot be sufficiently met by the Member States and that Union action shall not exceed what is necessary to achieve the objectives of the Treaty.107 We have already formulated a number of Union rationales for harmonizing Member States’ legislation on statelessness in section 4 above. The most forceful subsidiarity argument for EU legislative action is that within 107 Art. 5(3)-(4) TEU. European Journal of Migration and Law 19 (2017) 101–135