Sincere cooperation

According to Article 4 (3) TEU, the Union and Member States shall, pursuant to the principle of sincere cooperation and in full mutual respect, assist each other in carrying out tasks which flow from the Treaties. Member States shall take all necessary measures to ensure that their obligations under the Treaties and EU secondary legal acts are fulfilled. They shall also assist the Union to fulfil its undertakings, and refrain from any measure that may jeopardise fulfilment of the Union’s objectives. The duty of sincere cooperation has in practice been interpreted as an obligation on Member States’ competent authorities to use any available means to achieve the Union’s objectives.^{[1] [2] [3] [4] [5] [6] [7] [8]} Practical and political obstacles to implementation of EU law cannot normally be considered. In a case concerning a Member State’s failure to act against individuals whose actions undermined the free movement of goods within the EU, the Court of Justice held:

It is for the Member State concerned, unless it can show that action on its part would have consequences for public order with which it could not cope by using the means at its disposal, to adopt all appropriate measures to guarantee the full scope and effect of Community law so as to ensure its proper implementation in the interests of all economic operators.16⁴

Member States have also specific obligations to act or refrain from acting when the Commission has already submitted a proposal to the Council, which, even if not yet adopted by the Council, constitutes the starting point for a coordinated EU measure.165

The duty of sincere cooperation is also applicable in situations when Member States are entitled to enter into legal obligations in relation to third countries.166 The implications of the principle of sincere cooperation for a Member State’s action in the framework of an international environmental protection convention to which both the EU and the Member State are parties were dealt with by the Court of Justice in Case C-246/07, Commission v Sweden. 16⁷ This will be discussed further in Chapter 5.

The principle of sincere cooperation is reciprocal; hence, the Commission, also, is obliged to cooperate with Member States and not to take measures that prevent them from fulfilling their obligations under EU law.16⁸ The Court of Justice found in the Intertanko case that according to the principle of sincere cooperation and the international-law principle of good faith, it had to interpret a directive and a convention to which EU is a party in the light of the MARPOL 73/78 Convention,^ even though the EU itself was not a party to the latter but Member States wereTh⁰

In this way, the risk of Member States being forced to choose between acting according to EU law or to international law obligations is eliminated or at least reduced.

EU institutions are also required to cooperate sincerely with each other, for example in relation to consultation procedures.^{[9] [10] [11] [12] [13] [14] [15]} One expression of this is that the Council cannot decide about accession to an international convention in a way that prevents the Commission from complying with its international law obligations. 172

• [1] Case C-165/91 van Munster ECLI:EU:C:1994:359.
• [2] 164 Case C-265/95 Commission v France ECLI:EU:C:1997:595, para 56.
• [3] Case C-804/79 Commission v United Kingdom ECLI:EU:C:1981:93, para 28.
• [4] 166 Case C-266/03 Commission v LuxemburgECLI:EU:C:2005:341, para 58.
• [5] Case C-246/07 Commission v Sweden ECLI:EU:C:2010:203.
• [6] Case C-523/04 Commission v Netherlands ECLI:EU:C:2007:244, para 34.
• [7] International Convention for the Prevention of Pollution from Ships as amended by its 1978protocol (MARPOL 73/78) 1340 UNTS 184.
• [8] Case C-308/06 Intertanko and Others ECLI:EU:C:2008:312, para 52.
• [9] Case C-65/93 Parliament v Council ECLI:EU:C:1995:91, para 23.
• [10] 172 Case C-29/99 Commission v CouncilECLI:EU:C:2002:734, para 69.
• [11] For a comprehensive study of these principles, see Horspool and Humphreys European UnionLaw (n 83) 125—9; Barnard and Peers European Union Law (n 86) 206—12.
• [12] Case C-115/08 Land Oberosterreich v CEZ ECLI:EU:C:2009:660, para 92.
• [13] Ibid, para 139.
• [14] 176 Case C-344/04 International Air Transport Association ECLI:EU:C:2006:10, para 95 and theother cases referred to there.
• [15] Case C-127/07 Arcelor Atlantique and Lorraine and Others ECLI:EU:C:2008:728, para 47.