D. GALLO, Direct Effect in EU Law

It is quite a challenge to write a book on the principle of direct effect, especially given the extensive body of literature that has been developed ever since the Court of Justice of the European Union (the ‘Court of Justice’ or the ‘Court’) delivered its seminal ruling in van Gend en Loos back in 1963.¹ This is also because that principle brings together the role of individual rights in European integration with the autonomy of EU law, while also defining EU law’s relationship with both national and international law. From an academic perspective, and in light of the thousands – if not tens of thousands – of pages one must read to master this principle, Professor Gallo’s book is a highly valuable contribution.

His legal, theoretical, and contextual analysis of the principle of direct effect not only injects fresh perspective into academic discussions on the nature, content, and implications of the principle, but also thoroughly engages with the case law of the Court of Justice. This last aspect is of the utmost importance, given that the principle of direct effect is, after all, a judge-made principle (or, to put it in the beautiful Italian language, ‘un principio pretoriano’).

The book is not only descriptive in that it provides the reader with the relevant information to understand the principle of direct effect, but also normative in that it puts forward a series of arguments which seek to improve the coherence and clarity of the existing case law.

After a brief introduction, the book is divided into seven chapters, which aim to provide the reader with a comprehensive overview of the principle of direct effect. As might be expected, Chapter I opens with a detailed explanation of the judgment of the Court in van Gend en Loos. In the Author’s view, that judgment did not come as a surprise, but was instead ‘the product of an evolution of case law’.² The judgment of the Court of Justice in van Gend en Loos placed individuals at the centre of European integration, inasmuch as the principle of direct effect – as derived from that judgment – ‘implies the granting of rights to individuals and, consequently, the creation of a subjective legal position’.³ Coupled with the principle of primacy, the principle of direct effect has enabled EU law to become an ‘independent source of law’, thereby bringing the European integration project closer to its citizens.

In Chapter II, the book makes the argument that the principle of direct effect and the preliminary ruling procedure have acted as a ‘motor of integration’.⁴ On the one hand, the principle of direct effect empowers national courts to set aside national laws that are incompatible with EU law. On the other hand, through the preliminary ruling procedure, national courts can engage in a dialogue with the Court of Justice on questions of EU law, which guarantees the uniform interpretation of that law. Taken together, this means that national courts — in cooperation with the Court of Justice — can serve as ‘legal vigilantes’ for the rights that EU law confers on individuals and, thus, for the effective enforcement of that law. As the Author rightly emphasises later on, this illustrates the inextricable link between the principle of direct effect and the right to effective judicial protection. The last part of this chapter sets the stage for the Author’s normative views on the principle of direct effect: the case law of the Court of Justice suffers from contradictions, inconsistencies and a lack of clarity, which make ‘direct effect a very imprecise notion, difficult to frame in a legal sense, particularly in its ambit of application and objectives’.⁵

In Chapter III, the Author observes that the concept of ‘direct effect’ is inherently dynamic and has evolved over time, notably by broadening its scope. This point is illustrated by the application of that principle to horizontal situations, including fundamental rights. Next, he posits that three requirements must be fulfilled in order for a provision to be directly effective, namely, precision, clarity and unconditionality. However, he takes the view that this three-pronged test is outdated, given that the case law reveals that it is ultimately the unconditional nature of the provision, which relates to the degree of discretion left to the Member States in the application of EU law,⁶ that is decisive. A provision that is immediately/directly applicable and thus justiciable without the need for any further intermediary of national law, is unconditional and therefore, directly effective.

Chapter IV is one of the central chapters of the book in which the Author makes the case for the ‘decoupling’ between the principle of direct effect and the conferral of rights, departing from the original concept of direct effect put forward by the Court in van Gend en Loos. It is true that the conferral of EU rights is essential for the ‘subjective-substitutive’ dimension of direct effect: the EU right in question ‘cancels and replaces’ conflicting national laws. However, the principle of direct effect should be interpreted broadly so as to include an ‘objective-exclusionary’ dimension: the EU provision in question does not confer EU rights but may be relied upon in order to set aside conflicting national laws (as a standard of legality). To be clear, the Author is not arguing in favour of the applicability of non-directly effective provisions by virtue of the principle of primacy alone. An argument that was explicitly discarded by the Court of Justice in the seminal judgment in Popławski II.⁷ Instead, finding support in the case law and academia,⁸ he favours a broad understanding of direct effect, which includes ‘objective direct effect’. First, such inclusion is not new and can be found in national legal systems. Second, individuals can benefit from unconditional norms that do not confer rights upon them. Third, objective direct effect should not be construed as a ‘by-product’ of subjective direct effect. This is because ‘domestic provisions can be applied and govern the case at hand autonomously’.⁹ Fourth, the case law reveals that objective direct effect can take place beyond the scope of EU provisions of a technical nature imposing procedural obligations upon the Member States (as it results from the CIA Security International, Unilever and more recently, Airbnb line of case law).¹⁰

Chapter V focuses on the duty of national courts to disapply conflicting provisions of national law. It is the combined effect of the twin principles of primacy and direct effect that justifies that duty. Similarly, because those twin principles work together, some of the limitations examined by the Author may also be explored under the prism of the principle of primacy. This is the case of the principle of res judicata, limitations on the temporal scope of the Court of Justice rulings and the Taricco Saga.¹¹ By contrast, other limitations are specific to the principle of direct effect, such as the prohibition against horizontal direct effect of directives and that against inverse vertical direct effect, which respond to different rationales. In relation to the latter prohibition, the Author expresses his concerns about the judgment of the Court of Justice in Infraestruturas de Portugal.¹² If the Court were to follow a broad reading of that judgment applying its rationale beyond the bounds of public procurement law, the prohibition against inverse direct effect would be called into question. In that regard, the Author argues that inverse direct effect should be handled with the greatest care and should apply only prospectively. This is because EU law provisions that are directly effective cannot be detrimental for all private parties involved in a dispute.

In Chapter VI, entitled the ‘Controversial Horizontal Direct Effect’, the Author makes what is probably the most bold (and yet, rather convincing) argument contained in the book. He posits that the techniques developed by the Court – such as a broad understanding of public authority,¹³ triangular situations,¹⁴ the expansion of consistent interpretation,¹⁵ and the case law on the Charter¹⁶ – to get around the ‘no horizontal direct effect rule’, particularly with regard to directives, are rather unsatisfactory.¹⁷ That is why the Court should discard that rule and recognise the horizontal direct effect of directives. Notably, in order to make his case, the Author argues in favour of ‘spinning’ the principle of legitimate expectations, which has been relied upon by the Court to deny such effect. He observes that ‘[t]he paradox resulting from the prohibition of horizontal direct effect of directives is that [the private party] who acts in conformity with a directive is at a disadvantage compared to [the private party] who acts contrary to that directive, but in conformity with national law—a law that, in any case, must be amended to ensure conformity with the EU legal system’.¹⁸ Why should the legitimate expectations of the former invariably yield to those of the latter? This is not the best solution, given that a directive is a legal source superior to domestic law.

Chapter VII is different from the previous chapters in that it focuses on the direct effect of international law within the EU legal order. In this chapter, the Author highlights the contrast between the ‘internal’ direct effect of EU law and the ‘external’ direct effect of international law. While in respect of the former the Court of Justice has adopted a rather broad interpretation, the latter is subject to strict conditions that seek not to undermine the external action of the EU and to serve as a sign of judicial self-restraint: the EU judiciary should not enter into the realm of politics. By examining the current practice of the EU institutions, the Author observes that those institutions tend to include a ‘no-direct effect clause’ in new international agreements, thereby diminishing the role of the Court of Justice as the gatekeeper of secondary EU law complying with international law.

The conclusion is my favourite part of the book, because in four pages the Author manages to summarise the thrust of his arguments. This is quite remarkable and shows the sharpness and coherence of the ideas he supports.

In a clear and entertaining style, the book written by Professor Gallo will soon become a classic of EU literature, as it contains a thorough and critical overview of the case law of the Court of Justice on the principle of direct effect. It thus provides the reader with all the necessary elements to understand fully the nature, objectives, and dynamics underpinning that principle.

Students, scholars, and practitioners will all benefit greatly from it. On all accounts, it is a great pleasure to welcome this book.

¹ Court of Justice, 5 February 1963, Case 26/62, van Gend & Loos, ECLI:EU:C:1963:1.

² D. Gallo, Direct Effect in EU law, OUP, Oxford, 2025, p. 12.

³ Ibid., p. 22.

⁴ Ibid., p. 48.

⁵ Ibid. p. 55.

⁶ Ibid. p. 95.

⁷ Court of Justice, 24 June 2019, Case C‑573/17 Popławski II, ECLI:EU:C:2019:530.

⁸ The Author refers to the ‘Becker Formula’. See Court of Justice, 19 January 1982, Case 8/81, Becker, ECLI:EU:C:1982:7. As to academic literature, the Author refers to the works of Prechal, Ruffert and van Gerven. See D. Gallo, op. cit., pp. 107 to 109.

⁹ Ibid., p. 112.

¹⁰ Court of Justice, 30 April 1996, Case C‑194/94, CIA Security International, ECLI:EU:C:1996:172; 28 January 1999, Case C‑77/97, Unilever, ECLI:EU:C:1999:30; and 19 December 2019, Case C‑390/18, Airbnb Ireland, ECLI:EU:C:2019:1112.

¹¹ Court of Justice, 8 September 2015, Case C‑105/14, Taricco and Others, ECLI:EU:C:2015:555; and 5 December 2017, Case C‑42/17, M.A.S. and M.B., ECLI:EU:C:2017:936.

¹² Court of Justice, 21 December 2023, Case C‑66/22, Infraestruturas de Portugal and Futrifer Indústrias Ferroviárias ECLI:EU:C:2023:1016.

¹³ Court of Justice, Case C‑413/15, 10 October 2017, Farrell, ECLI:EU:C:2017:745.

¹⁴ Court of Justice, Case C‑201/02, 7 January 2004, Wells, ECLI:EU:C:2004:12.

¹⁵ Court of Justice, 18 January 2022, Case C‑261/20, Thelen Technopark Berlin, ECLI:EU:C:2022:33.

¹⁶ See, e.g., Court of Justice, Case C‑414/16, 17 April 2018, Egenberger, ECLI:EU:C:2018:257.

¹⁷ See D. Gallo, op. cit., p. 238 (arguing that ‘[w]hat is certain is that the EU jurisprudence on horizontality and directives is, to date, a minefield, studded with alternative solutions and argumentative palliatives that undermine the principle of legal certainty and the related principle of legitimate expectations’).

¹⁸ Ibid., p. 242.