Introduction
European Union (EU) law plays a decisive role in the legal order of the Member States, as it penetrates national legal systems and shapes key aspects of their legal orders. The effectiveness of EU rules depends largely on how they are applied both by national authorities and by individuals. In this context, two fundamental principles that guarantee the enforcement of EU law at national level are direct effect and indirect effect.
The principle of direct effect allows EU rules to create rights and obligations which individuals can invoke directly before national courts, without the need for further national implementing measures. This possibility derives from the case law of the Court of Justice of the European Union (CJEU) and has contributed significantly to strengthening the primacy of EU law. Indirect effect, on the other hand – also known as the principle of consistent interpretation – imposes on national courts an obligation to interpret domestic law, in so far as possible, in a manner consistent with EU law, even when the latter does not have direct effect.
Although both principles aim at ensuring the uniform application of EU law, their operation is subject to specific conditions and limitations. Analysing the conditions for their application, as well as the obstacles that arise in judicial practice, highlights the dynamic relationship between national and EU law and the crucial role of case law in shaping the effectiveness of EU rules.
The notion of direct and indirect effect
Direct effect
Direct effect refers to the principle whereby individuals can rely directly on provisions of EU law before national courts, without the need for those provisions to be transposed by national legislation. This principle was formulated in the judgment in Van Gend en Loos (Case 26/62), where the Court of Justice of the European Union (CJEU) held that EU law does not merely impose obligations on Member States, but also confers rights on individuals which they can assert in court.1
Direct effect can be divided into vertical and horizontal, depending on the relationship between the parties. Vertical direct effect concerns relations between individuals and the state. This means that an individual may invoke a provision of EU law against the state or state bodies, thereby ensuring that Member States comply with their obligations arising from EU law. Horizontal direct effect, by contrast, refers to the possibility for an individual to invoke EU law against another individual in private disputes. This distinction is particularly important, as the Court of Justice has recognised full direct effect (that is, both vertical and horizontal) only for certain types of EU acts. For example, Treaty provisions and Regulations may have both vertical and horizontal direct effect, provided that the criteria laid down in the case law are satisfied. Directives, by contrast, which bind Member States only as to the result to be achieved, have vertical direct effect only and cannot be relied upon in disputes between private parties.2
Direct effect was consolidated in the case law of the Court of Justice of the European Communities (CJEC) with the judgment in Van Gend en Loos (1963), which became a landmark for the application of EU law in the Member States. The case concerned the imposition by the Dutch authorities of increased customs duties on imports of chemical products from Germany, which the company Van Gend en Loos claimed was contrary to Article 12 of the EEC Treaty (now Article 30 TFEU), which prohibited the introduction of new customs duties or the increase of existing ones. The key question before the CJEC was whether this provision created rights that individuals could invoke directly before national courts. The Court held that EU law is not addressed exclusively to the Member States, but produces immediate effects and creates rights for individuals which national courts must protect. It further held that, in order for a provision to have direct effect, it must be clear, precise and unconditional, and must not depend on further national or EU implementing measures. Through this judgment, the CJEC recognised the obligation of national courts to ensure the application of EU law and to protect the rights arising from it. At the same time, Van Gend en Loos established vertical direct effect, namely the right of individuals to invoke provisions of EU law against state authorities, thereby strengthening the immediate force and primacy of EU law.3
The importance of this case law becomes apparent when compared with public international law, where, in the event of a breach of an international treaty, the disobedient state is exposed to “horizontal” risks, namely sanctions or countermeasures from other states, but not to “vertical” risks, as individuals cannot normally bring actions before national courts to enforce the provisions of the treaty, since they are not contracting parties. In EU law, by contrast, the recognition of direct effect allows individuals to claim rights before national courts, making EU law more effective than classical international legal orders.4
Indirect effect
Indirect effect, also referred to as the principle of consistent interpretation, imposes on national courts an obligation to interpret their domestic law in conformity with EU law, in so far as possible. This principle ensures that EU law influences the way national provisions are applied and interpreted, reinforcing its primacy over interpretations that would be inconsistent with EU rules.5 In doctrinal terms, it is an interpretative principle which requires national courts to construe domestic law (especially legislative acts transposing EU directives) in a manner consistent with EU law, even where the latter does not have direct effect.6
The importance of this principle emerged through the case law of the Court of Justice, notably in Von Colson (1984). In that case, two social workers brought an action against the Land of North Rhine-Westphalia, claiming that they had not been recruited to work in a prison because of their sex, even though they had more qualifications than the male candidates selected. German law, although it had transposed Directive 76/207/EEC on equal treatment for men and women in employment, provided only for reimbursement of application expenses as a remedy, without securing genuine and effective legal protection. The Court held that, even though the Directive did not have direct effect, the national court was required to interpret domestic law in the light of its objectives, so as to ensure the full application of the principle of equal treatment.
This interpretative obligation was strengthened further in Marleasing (1990), where the Court adopted an important interpretative approach. The case concerned a dispute between private parties, in which one party argued that a company had been incorporated in breach of the national civil code, while the other relied on a Directive providing for different grounds of nullity. The Court held that the principle of consistent interpretation is not limited to provisions adopted to transpose a Directive, but extends to the entire body of national law. Consequently, Member States are required to interpret all domestic law in a way that is compatible with EU law, even if the relevant national provisions were enacted before the Directive was adopted. Through this judgment, the Court firmly established the broad scope of indirect effect, preventing Member States from maintaining national rules that could undermine the objectives of EU law, where those rules are open to a conforming interpretation.7
Limitations on direct and indirect effect
Although direct and indirect effect contribute to the effective application of EU law, their operation is not unlimited. There are specific constraints which derive both from the nature of EU provisions and from the case law of the Court of Justice of the European Union (CJEU).
Limitations on direct effect
Direct effect does not apply to all provisions of EU law. For a provision to have direct effect, it must be clear, precise and unconditional, and must not require further national implementing measures. The CJEU developed this criterion in Van Gend en Loos (Case 26/62). However, where EU law leaves a margin of discretion to the Member States, direct effect is not recognised. In Becker (Case 8/81), the Court held that a provision requiring national implementing measures could not have direct effect. Moreover, Directives do not have horizontal direct effect, that is, they cannot be relied upon by an individual against another private party. This was confirmed in Faccini Dori (Case C-91/92), where the Court refused to extend the direct effect of Directives to disputes between private parties.8
Furthermore, the principle of the primacy of EU law may be constrained by certain constitutional reservations in some Member States. In Costa v ENEL (Case 6/64), the Court established that EU law prevails over national law, but its application may encounter limits stemming from fundamental constitutional principles in the domestic legal order.
Limitations on indirect effect
The principle of indirect effect, as established in Von Colson (Case 14/83), requires national courts to interpret their domestic law in conformity with EU law. However, this obligation applies only where such an interpretation is possible under national law. If a national provision is in direct and unavoidable conflict with EU law, consistent interpretation cannot be used to bridge the gap.
In Marleasing (Case C-106/89), the Court clarified that the duty of consistent interpretation applies even to national provisions adopted before the Directive. Nevertheless, the obligation of consistent interpretation cannot lead to a contra legem interpretation, that is, an interpretation that runs counter to the clear wording of national law. Finally, where consistent interpretation is not possible, the only remedy available to an individual may be an action for damages against the state, based on the principle of state liability, as developed in Francovich (Joined Cases C-6/90 and C-9/90).9
On the basis of these limitations, direct and indirect effect, although essential tools for the application of EU law, cannot go beyond the boundaries set by the case law of the CJEU and the domestic legal order.
Conclusion
Direct and indirect effect constitute fundamental principles of EU law, ensuring the effective application of EU rules in the Member States. Direct effect allows individuals to invoke provisions of EU law directly before national courts, while indirect effect imposes on courts a duty to interpret domestic law in conformity with EU law. The consolidation of these principles in the case law of the Court of Justice has contributed to the emergence of a unified legal order, reinforcing the primacy of EU law and the judicial protection of individual rights.
However, the application of these principles is not without limits. Direct effect is subject to strict criteria, such as the clarity and unconditional nature of the relevant provisions, and Directives are not recognised as having horizontal direct effect. Similarly, indirect effect cannot lead to a contra legem interpretation, and its operation depends on the interpretative limits of national law. These constraints make it clear that, despite their dynamic character, the principles operate within the framework laid down by the CJEU’s own case law.
Direct and indirect effect therefore play a crucial role in safeguarding the uniform application of EU law, while at the same time reflecting the limits of EU intervention in national legal systems. The balance between strengthening the legal protection of individuals and preserving the autonomy of the Member States remains a field in constant development and interpretation, mirroring the ongoing interaction between national and EU law.
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[1] “The difference between Direct and Indirect Effect”, AskanAcademic.com, 20 September 2019, [https://askanacademic.com/law/the-difference-between-direct-and-indirect-effect-34/](https://askanacademic.com/law/the-difference-between-direct-and-indirect-effect-34/) (last accessed 16/02/2025).
[2] «Το άμεσο αποτέλεσμα του δικαίου της Ευρωπαϊκής Ένωσης» [The direct effect of European Union law], EUR-Lex, [https://eur-lex.europa.eu/legal-content/EL/TXT/?uri=LEGISSUM:l14547](https://eur-lex.europa.eu/legal-content/EL/TXT/?uri=LEGISSUM:l14547) (last accessed 16/02/2025).
[3] Νόρα Κούρτη, «Van Gend en Loos: Μια υπόθεση ορόσημο για τη θεμελίωση της ευρωπαϊκής αρχής του άμεσου αποτελέσματος» [Van Gend en Loos: A landmark case for establishing the European principle of direct effect], 22 March 2022, Offline Post, [https://www.offlinepost.gr/2022/03/22/van-gend-en-loos-mia-ipothesi-orosimo-gia-ti-themeliosi-tis-evropaikis-arxis-tou-amesou-apotelesmatos/](https://www.offlinepost.gr/2022/03/22/van-gend-en-loos-mia-ipothesi-orosimo-gia-ti-themeliosi-tis-evropaikis-arxis-tou-amesou-apotelesmatos/) (last accessed 16/02/2025).
[4] Αλέξανδρος Τσαδήρας, «Εισαγωγή στο Δίκαιο της Ευρωπαϊκής Ένωσης» [Introduction to European Union Law], Sakkoulas, p. 78.
[5] “The difference between Direct and Indirect Effect”, AskanAcademic.com, 20 September 2019, [https://askanacademic.com/law/the-difference-between-direct-and-indirect-effect-34/](https://askanacademic.com/law/the-difference-between-direct-and-indirect-effect-34/) (last accessed 16/02/2025).
[6] “Indirect effect (EU)”, Thomson Reuters Practical Law, [https://uk.practicallaw.thomsonreuters.com/7-107-6712](https://uk.practicallaw.thomsonreuters.com/7-107-6712) (last accessed 16/02/2025).
[7] Άννα Α. Αρναούτη, «Η σύμφωνη με το ενωσιακό δίκαιο ερμηνεία του εθνικού δικαίου» [Consistent interpretation of national law with EU law], LL.M. thesis, September 2016, pp. 6–11.
[8] Ευγενία Πρεβεδούρου, «Άμεσο αποτέλεσμα των οδηγιών – Δυνατότητα επίκλησης των οδηγιών παρά την έλλειψη μεταφοράς τους στην εθνική έννομη τάξη» [Direct effect of directives – Possibility of invoking directives despite lack of transposition into national law], 22 April 2014, [https://www.prevedourou.gr/΄αμεσο-αποτελέσμα-των-οδηγιών-δυνατό/](https://www.prevedourou.gr/΄αμεσο-αποτελέσμα-των-οδηγιών-δυνατό/) (last accessed 16/02/2025).
[9] Ευγενία Πρεβεδούρου, «Η αστική ευθύνη των κρατών μελών λόγω παραβιάσεων του δικαίου της Ένωσης» [Civil liability of Member States for breaches of EU law], 17 June 2014, [https://www.prevedourou.gr/h-αστική-ευθύνη-των-κρατών-μελών-λόγω-πα/](https://www.prevedourou.gr/h-αστική-ευθύνη-των-κρατών-μελών-λόγω-πα/) (last accessed 16/02/2025).
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* This article is based on a university assignment that was completed in 2025 as part of my Law studies at the Open University of Cyprus. This article is for informational purposes only and does not constitute legal advice.
