Sincere cooperation

A legal limit to sincere cooperation has been imposed within the same Article 4:

2. The Union shall respect the equality of Member States before the Treaties as well as their national identities, inherent in their fundamental structures, political and constitutional, inclusive of regional and local self-government. It shall respect their essential State functions, including ensuring the territorial integrity of the State, maintaining law and order and safeguarding national security. In particular, national security remains the sole responsibility of each Member State.

Right before the principle of sincere cooperation is introduced, the legislator notes the importance of national identities.^[2] Therefore, by looking at Article 4(2) and 4(3) TEU simultaneously, there are "constitutional limits in an institutional and procedural framework" that are inherent to the framework around which the principle of sincere cooperation operates.^[16] Simultaneously, this does not infer that national identity enjoys supreme power within the Union's system, yet it is balanced against the "uniform application of EU law" through a composite constitutional structure of the CJEU and the national courts and institutions.^[16] Precisely for this to function in practice, the principle of sincere cooperation is invoked again as it its importance is crucial for the coordination of this multi-dimensional jurisprudence.^[16]

Consequently, this once again, emphasizes the interconnection between national identities, sincere cooperation, and the Union's foreign policy. To this end, the Member States concerned for their rights to sovereignty within this multi-dimensional jurisprudence that requires sincere cooperation on an international level, have emphasized the non-exclusionary rights through Declarations 13 and 14 of the Lisbon Treaty: the mutual political solidarity and sincere cooperation on the CFSP EU level, "do not affect the responsibilities of the Member States... for the formulation and conduct of their [national] foreign policy...".^[13]

The EU legal order and the ECHR legal system are two separate ones, and while the EU is not a member of the Council of Europe, the Member States of the Union are; consequently, the principle of sincere cooperation has appeared in cases before the European Court of Human Rights.^[17]

The case Könyv-Tár Kft and Others v. Hungary (Application No. 21623/13) concerned three applicant companies, all schoolbook distributors, which claimed that the creation of a state monopoly on school books is a breach of Article 1 of the Protocol No.1, namely the peaceful enjoyment of possessions. In the ECtHR deliberations, the Court has made the following arguments regarding the principle of sincere cooperation as part of the European Union legislation:^[18]

38. The Court further notes that, in accordance with Article 267 of the TFEU and the well-established case-law of the CJEU, a preliminary rulinggiven by the CJEU is binding on the referring national court as to the interpretation of the provision of EU law in question. It clarifies and defines the meaning and scope of that provision as it must be, or ought to have been, understood and applied at the time it came into force. Furthermore, pursuant to the principle of “sincere cooperation”, the authorities of EU member States have the task of ensuring, within the sphere of their competence, that the rules of EU law, as interpreted by the CJEU, are observed and that individuals’ rights under EU law are judicially protected. Consequently, the Court considers that guidance provided by a preliminary ruling must be observed not only in the specific dispute which has given rise to the referral but also, indirectly, in other cases, even those concerning legal relationships which had arisen before the CJEU gave the ruling in question.

Here, the ECtHR notes the importance of sincere cooperation on a judicial level between the Court of Justice of the European Union and the national courts, while also stipulating that the Union's authorities have a responsibility to observe the practice of sincere cooperation within their conferred competence.^[18]

While the respect for national identities has been enshrined in Article 4 TEU, it is notable that post-Lisbon, for any competences that are not conferred on the Union where the Member States could exercise their sovereignty, they are still restricted in that they need to facilitate the Union's objectives and goals within their sovereignty—according to the principle of sincere cooperation.^[19] Consequently, Member States' interactions with the Union is continuously guided by the aforementioned principle. This has been reflected in CJEU case law in different areas of competence across the EU.

In Case C-516/22 Commission v United Kingdom of Great Britain and Northern Ireland decided on 14 March 2024, the Court assessed the judgment of the Supreme Court of the United Kingdom in the case Micula v Romania.^[20] The Supreme Court of the United Kingdom in the aforementioned case ordered Romania to pay a compensation to Swedish investors, despite the Commission prohibiting Romania to do so, as it was incompatible with EU law.^[21] As a result of the decision of the Supreme Court of the United Kingdom, the CJEU declared that "the United Kingdom has failed to fulfil its obligations under EU law":^[21]

"...Consequently, where the outcome of the dispute before the national court depends on the validity of the Commission decision, it follows from the obligation of sincere cooperation that the national court should, in order to avoid reaching a decision that runs counter to the Commission decision, stay its proceedings pending final judgment in the action for annulment before the Courts of the European Union, unless it takes the view that, in the circumstances of the case, a reference to the Court of Justice for a preliminary ruling on the validity of the Commission decision is warranted."

Therefore, the Court establishes a direct link through the principle of sincere cooperation between the national courts, and the institutions of the European Union:^[20]

"...In particular, the application of the rules of EU law on State aid laid down in Articles 107 and 108 TFEU is based on an obligation of sincere cooperation between, on the one hand, the national courts, and, on the other hand, the Commission and the Courts of the European Union, in the context of which each acts on the basis of the role assigned to it by the Treaty."

In the case (C-454/22), Commission v Latvia, the European Commission brought the Republic of Latvia before the Court for failing to adopt all the legal provisions by transposing "necessary to comply with Article 124(1) of Directive (EU) 2018/1972 of the European Parliament and of the Council of 11 December 2018 establishing the European Electronic Communications Code".^[22] Consequently, the Court has elaborated on the role of Member States in the process of transposition of a Directive, according to the principle of sincere cooperation:

"In that context, the Court has already held that the expression ‘obligation to notify measures transposing a directive’ in Article 260(3) TFEU refers to the obligation of the Member States to provide sufficiently clear and precise information on the measures transposing a directive. In order to satisfy the obligation of legal certainty and to ensure the transposition of the provisions of that directive in full throughout their territory, the Member States are required, in accordance with the principle of sincere cooperation laid down in Article 4(3) TEU, to state, for each provision of the directive, the national provision or provisions by means of which they consider that they have fulfilled the various obligations imposed on them by that directive. Once notified, where relevant in addition to a correlation table, it is for the Commission to establish, for the purposes of seeking the financial penalty to be imposed on the Member State in question laid down in Article 260(3) TFEU, whether certain transposing measures are clearly lacking or do not cover all of the territory of the Member State in question, bearing in mind that it is not for the Court, in judicial proceedings brought under that provision, to examine whether the national measures notified to the Commission ensure a correct transposition of the provisions of the directive in question."

In the case (C‑316/19), Commission (supported by the European Central Bank) v Slovenia, the Commission brought the Republic of Slovenia before the Court because it alleged that it breached the Union's law and failed to cooperate sincerely "by unilaterally seizing at the premises of the Banka Slovenije (Central Bank of Slovenia) documents connected to the performance of the tasks of the European System of Central Banks (ESCB) and of the Eurosystem".^[23] The Court, in its findings, focuses on the reciprocity of the relationship between the Union's institutions and the Member States:

"According to settled case-law of the Court, under the principle of sincere cooperation provided for in Article 4(3) TEU, the Member States are required to eliminate the unlawful consequences of a breach of EU law and such an obligation is owed, within the sphere of its competence, by every organ of the Member State concerned."

"Admittedly, the obligation of sincere cooperation is, by its very nature, reciprocal (judgment of 16 October 2003, Ireland v Commission, C‑339/00, EU:C:2003:545, paragraph 72). It was consequently for the ECB to assist the Slovenian authorities so that the latter could remedy, as far as possible, the unlawful consequences of its seizure of documents at the premises of the Central Bank of Slovenia on 6 July 2016."

Therefore, the Court establishes that even in a situation where there is a breach of Union's law on the side of the Member State, thus failing to adhere to the principle of sincere cooperation—reciprocity remains a core component of this principle, and a way to continue to uphold it is by providing assistance from the Union's institutions.^[23]