Choice of Legal Basis
As a consequence of the principle of conferred competence, every legal act adopted by the EU institutions must be based on a legal basis in the Treaties. The legal basis shows that the Union is entitled to legislate within the area and sets out the applicable procedure(s) for doing so. As discussed previously in this chapter, the choice between legal bases, such as Articles 192(1), 114(1), and 43(2) TFEU, for the adoption of a legal act can have significant implications for the division of competence between the Union and the Member States, as well as between the EU institutions involved in the legislative process. It also partly defines the room for more protective measures at Member State level. If an activity is deemed to fall within one of the areas in which the EU enjoys exclusive competence, such as the conservation of marine biological resources under the CFP, the Member States can only influence the regulation of that activity through the EU institutions.
Although the differences between legal bases have become smaller, for example through the strengthening of the powers of the EP in areas where it was previously only to be consulted, some important implications of the choice of legal basis also remain outside the area of exclusive EU competence. There are, for example, still areas, including land use and provisions primarily of a fiscal nature, where the EP is only to be consulted by the Council during the legislative process. The most significant difference, however, is perhaps the general right of Member States to take more stringent protective measures when an EU legal act has been based on Article 192(1) TFEU, which only has a very limited analogue in Article 114 TFEU, and none at all in legal bases such as Article 43 TFEU on the CAP.
The Court of Justice has established two main requirements that apply to the choice of legal basis. One is that the choice must be based on objective factors amenable to judicial review.96 These factors include in particular the aim and content of the measure.97 The other requirement is that the legal basis shall be used that is required by the ‘main or predominant’ purpose of the legal act.98 In this regard reference is often made to the ‘point of gravity’ of the legal act. If, exceptionally, it is established that an act simultaneously pursues a number of objectives, ‘indissociably linked, without one being secondary and indirect in relation to the other’, an act may be founded on two or more corresponding legal bases.99 More on this below.
The Court of Justice has repeatedly held that the legal basis which has been used for the adoption of other EU measures which display similar characteristics is irrelevant, as the legal basis for a measure must be determined having regard to the purpose and content of each specific measure.100 A close examination of each new measure is required. Some guidance may, however, be had from the fact that where the Treaty contains a more specific provision that is capable of constituting the legal basis for a specific measure, that provision is to be used.101 Whether the Court’s rather extensive case law on the choice of legal basis provides much clarity is, in itself, far from clear.
If the aims of an EU legal act cover more than one policy area it must be considered whether the measure relates principally to a particular field of action, having only incidental effects on other policies, or whether both aspects are equally essential. If the latter is the case the measure shall, in principle, be adopted on the basis of the two or more provisions from which the EU law-maker’s competence derives. Such dual basis is not possible where the procedure laid down for each legal basis are incompatible with each other.102 However, the Court of Justice has accepted the use of legal bases as long as the Council acts by a qualified majority under both procedures even though the EP has different levels of influence according to the 
procedures. As long as the procedure is applied which grants the EP the more extensive influence, its rights are not encroached upon.
The Court of Justice has found that dual legal bases should be used, inter alia, for the approval of the Rotterdam Convention and the adoption of a regulation implementing that Convention.103
-  6 Case 45/86 Commission v Council EU:C:1987:163, para 11 and subsequent case law. 97 Case C-300/89 Commission v Council ECLI:EU:C:1991:244, para 10. 98 See, eg, Case C-336/00 Huber (n 7), para 31. 99 Ibid, para 31. 1°° See, eg, Case C-656/11 United Kingdom v Council EU:C:2014:97, para 48. 101 Case C-15 5/07 Parliament v CouncilECLI:EU:C:2008:605, para 34. 102 Joined Cases C-164/97 and C-165/97 Parliament v Council (n 5), para 14 and the case lawcited there.