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EU Private International Law before the ECJ: A Look into Empirical Data

Private international lawyers and the ECJ are bound by a love-hate relationship: one single judgment delivered by the latter may sometimes give rise to a fully-fledged conference where, at the end of a lively discussions, the former express harsh criticisms, tepid approval or high praise towards the solution shaped by the Luxembourg Court. But while PIL scholars usually tend to dissect every substantive aspect of the Court’s ruling, little attention is usually paid to the ‘procedural’ context in which such decision has been reached. I admit that, before coming to Luxembourg, I myself took little notice of details such as the existence (or lack of) an AG’s Opinion, the reporting judge assigned to the case or the judicial formation having rendered the decision. However, these arguably are important indicators of the way in which a question concerning EUPIL is treated – both procedurally and substantively – by the Luxembourg Court.

Against this backdrop, it could be interesting, if not useful, to take a broader look at the relationship between the ECJ and EUPIL, going beyond the individual judgment and aimed at assessing preliminary rulings on this subject as a systemic phenomenon. The purpose of this analysis is twofold.

Firstly, it serves to disprove the belief – still held dear by some scholars – that PIL issues are ‘merely technical’ in nature. In fact, these are seldom treated as such in Luxembourg, as evidenced by the overwhelming majority of cases assigned to Chambers of five rather than to a Chamber of three. Moreover, since an Opinion of the AG is delivered in more than half of PIL cases, these often raise ‘new questions of law’, in the sense of Article 20 of the ECJ’s Statute. This finding holds true also with respect to instruments – such as the Brussels Regulations – that are of long-standing application in national courts and frequently interpreted in Luxembourg, thus confirming that, in PIL cases, facts and legal rules tend to combine in ever-changing constellations of interactions.

Secondly, the discussion may be useful in view of eventual future reforms of the ECJ’s internal structure and/or working methods. This Institution is presently coming under growing pressure owing to the ever-increasing number of cases introduced before it on a yearly basis. In 2021, this rise was deemed ‘significant’ and affected mostly the Court of Justice (see the Report ‘Year in Review’, p. 28). The reasons behind this surge of cases are, on the one hand, an increase in the appeals brought against rulings of the General Court (ibid, p. 28) and, on the other hand, the ever-growing number of preliminary references filed by national courts (in 2021, they accounted for the largest share (68%) of new cases brought before the Court: Management Report 2021, p. 6). According to President Lenaerts, the Court is currently engaged in ‘a reflection on how to achieve a rebalancing of the workload between the Court of Justice, composed of one judge per Member State, and the General Court, which, since September, has two judges per Member State’ (Report ‘Year in Review’, p. 5). Since the Court has already tackled – at least partially – the ‘appeals problem’ by introducing a filtering mechanism, this further ‘rebalancing’ might include, in theory, the transfer to the latter of some of the functions currently performed by the former, such has the delivery of preliminary rulings, following a sectoral approach limited to certain subject-matters. The question (purely hypothetical at present) as to whether – and to what extent – the field of civil cooperation in civil matters should be touched by this eventual ‘rebalancing’ should be addressed based on said systemic analysis of the relationship between the ECJ and EUPIL. Its aim is to identify trends – if any – in the adjudication of these cases and to decipher their meaning.


The two objectives stated above can be best served with the assistance of empirical legal research. To my knowledge, there is no existing data (institutional or otherwise) that specifically concerns PIL cases brought before the ECJ. The Charts appearing in the following sections are therefore drawn from a repository of cases I compiled myself based on the information which is publicly available on EUR-LEX and Curia, or was made public at the hearing. This repository puts together the requests for preliminary rulings filed and/or decided with respect to EUPIL instruments from January 2015 to August 2022.

For the purposes of this research, ‘EUPIL’ is understood as encompassing the Brussels-Lugano Regime (Regulations 44/2001 and 1215/2012 as well as the Lugano II Convention), the Brussels II Regime (limited to Regulation 2201/2003, since there are presently no cases on Brussels II-ter), the Rome Regulations (593/2008, 864/2007 and 1259/2010); the Succession Regulation and the ‘smaller’ Regulations (EAPO, EPO, EEO, ESC, Service and Evidence I Regulations). The Regulations on matrimonial and registered partnership property issues have been taken into account, but there is currently no request for interpretation concerning them.

The selected time-frame (2015-2022) has been identified based on the (debatable) assumption that the last 7 years could provide for ‘meaningful’ empirical evidence concerning the application of all the above mentioned instruments, including the eldest, the Brussels I Regulation (which still applies to legal proceedings instituted, to authentic instruments formally drawn up or registered and to court settlements approved or concluded until 9 January 2015).

The numerical labels appearing in the Charts refer not to the number of cases filed with the ECJ, but to the number of preliminary references raised with respect to each instrument (e.g. if one case raised questions concerning two different EUPIL instruments, it was counted twice).

General Overview

Overall, there are 245 preliminary references concerning EUPIL instruments in the selected timeframe. Unsurprisingly, the Brussels-Lugano regime accounts, alone, for more than 50% of the total references submitted to the ECJ, followed by Reg. 2201/2003 as a far second (12 %). The Rome Regulations, taken together, make up for another 12 % of the total cases.

A closer look at the geographical origin of the preliminary references confirms that EUPIL preliminary references are not equally distributed across the Member States.

National courts in Germany and Austria have indisputably acquired a leading role as triggers of EUPIL case law and of its evolution over the past 7 years. Rather surprising is the data concerning Luxembourg, where the ‘cross-border dimension’ of cases is almost a daily occurrence. This suggests that there is no necessary correlation between the application rate of EUPIL instruments and the number of preliminary references submitted to the ECJ.

Opinions of the AG and Judicial Formations.

Data from the last seven years shows that a generous majority of EUPIL cases commands an Opinion of the AG. The percentages shown in Chart 5, below, are based on aggregated data concerning all EUPIL instruments, as defined above sub A.

In actual truth, there are perceivable sectoral variations, across the several instruments, with this percentage hovering between a maximum rate of 80 % in the Succession Regulation to a minimum of 33% under the EEO Regulation (except, of course, for the 0% rate that characterizes the Evidence and the ESC Regulations). The Charts below give a good idea of such sectoral variations.

Another good indicator of the relative ‘weight’ of EUPIL cases (and of the importance of the legal questions raised therein) is the number of preliminary references that, owing to their difficulty, their importance for Union Law or the particular circumstances surrounding them, are assigned to the Grand Chamber (cf Article 60 of the Rules of Procedure of the Court).

In this respect, it is apparent from the Charts below that the field of EUPIL is characterized by a relatively low number of Grand Chamber cases (6 cases in total over the last 7 years, ie 3 %). As a reminder, these Grand Chamber cases are:

The vast majority of cases remains assigned to Chambers of five, which is the ordinary formation of the Court. Chambers of three, which are reserved to cases that are either highly technical in nature or of straightforward solution, are less frequent in EUPIL, accounting for around one quarter of the total cases. These are relatively more common under the Brussels I and Ibis Regulation, possibly because of the existence of a long-standing and well-developed body of case law that may better contribute to the straightforward solution of the case.

Interestingly, there is a certain number of cases assigned to a Chamber of three but decided with the support of an AG Opinion. This may, at first (and only at first), seem like a contradiction in terms. As mentioned above, the Opinion of the AG should, in principle, be delivered solely in cases that raise ‘new questions of law’. In practice, however, it is apparent that Opinions have been asked under other circumstances, presumably to help the drafting of the future judgment, or because different approaches to the solution of a case could easily be envisioned. Hence, it is not inconceivable that a case may be, at once, highly technical in nature – thus justifying the deferral to a Chamber of three – and open to different alternative solutions, calling therefore for the advisory assistance of the AG (as it was the case in C-214/17, where AG Szpunar explicitly evokes the doubts expressed by the referring court concerning two alternative approaches to the solution of the question raised, §21-23). Similarly, a case can present a question which is at the same time highly technical in nature, but ‘novel’ in the sense of Article 20 of the Statute, as it might have been the case in C-555/18, concerning the weight to be attached to the requirement of enforceability for the purposes of the uniform definition of ‘authentic instrument’ under the EAPO Regulation (there was, in that case, a target Opinion by AG Szpunar).

The Form of the Decision

Another and more significant pointer to the ‘novelty’ of the legal questions raised by EUPIL cases is the form taken by the decision finally delivered by the ECJ.

It should be reminded that the ECJ usually rules through judgments (arrêts, in French), but it can exceptionally adopt a ‘reasoned order’ where (a) a question referred to the Court for a preliminary ruling is identical to a question on which the Court has already ruled ; or (b) where the reply to such a question may be clearly deduced from existing case-law ; or (c) where the answer to the question referred for a preliminary ruling admits of no reasonable doubt (Article 99 of the Rules of Procedure). Moreover, where it is clear that the Court has no jurisdiction to hear and determine a case or where a request or an application is manifestly inadmissible, the Court can decide to give a decision by reasoned order without taking further steps in the proceedings (Article 53 (2) Rules of Procedure).

Against this backdrop, the more surprising result is not so much the high number of judgments delivered in EUPIL matters, but rather the extremely low number of Article 99 Orders, even more so with respect to the Brussels I Regulation, which has by now undergone almost two decades of application and interpretations by the Luxembourg Court, and could itself profit from the interpretive rulings previously rendered under the 1968 Brussels Convention according to the 1971 Protocol.

Considering the high recurrence rate of questions concerning the interpretation of certain specific provisions of the Brussels Regulations, such as those dealing with the heads of jurisdiction in contractual matters and torts, consumer contracts and exclusive or prorogated jurisdiction, the low number of Article 99 Orders means, in practice, that the application of such provisions to concrete facts continues to give rise to new scenarios, with respect to which existing case law provides for an answer that is either partial, incomplete or open to further interpretation.

Informal Specialization

The final aspect considered by this empirical research relates to the (only apparent) lack of internal specialization within the ECJ, in the sense that this Institution is not formally divided into Chambers dedicated to specific subject-matters. Each of the Chambers of the Court, whatever the judicial formation, can in fact hear cases relating to any matter that falls within the jurisdiction thereof. Considering the wide scope of EU law and in the light of the current challenges brought by the inflating number of new cases, this lack of specialization of the Court’s Chambers could be seen as a hindrance to the Institution’s efficiency. Again, this conclusion must be nuanced, if not completely set aside, based on the analysis of the Court’s case law. Despite the lack of institutional specialized Chambers, the Court has developed an internal system for the allocation of cases among reporting judges and AGs which favours, at once, informal specialization and flexibility. Concerning the latter, the internal allocation of cases must be flexible enough to accommodate the contingent organizational needs of an Institution of such size, such as, for example, the need of ensuring an equal distribution of cases and expedited treatment of PPU cases or of avoiding national or other kinds of bias. Concerning specialization, existing case law clearly shows that certain judges and AGs that have been consistently entrusted, over the time, with EUPIL cases.

(***Note of the Author: data about Reporting Judges are incomplete, as this information is not disclosed with respect to cases that have been withdrawn and removed from the register. The Order of the President only mentions the designated AG***)

Obviously, this is not to say that the final decision on the case will reflect exclusively or even predominantly the individual views of these judges. Rather, this decision will always be the result of the collective will emerged from the discussion within the Chamber (of five or of three judges). This informal specialization of the Reporting Judge and of the AGs ensures nonetheless the efficient working of the Institution at the initial stage of the proceedings, concerned with the preliminary analysis of the case geared towards the identification of the appropriate judicial formation and of other procedural needs (eg. the need for further written clarifications or for an oral hearing). It could also favour, over time, a certain consistency in the (procedural and substantive) approach adopted with respect to recurrent issues, thus enhancing the overall coherence of the Court’s case law in EUPIL.

Legal Assistant at the ECJ. The opinions expressed in this publication are those of the author. They do not purport to reflect the opinions or views of the ECJ or its Members.

3 comments on “EU Private International Law before the ECJ: A Look into Empirical Data

  1. Burkhard Hess

    Congratulations, Martina! This is a vey thorough and thought provoking article. Very well done.

  2. Martin Margonski

    A great piece of analysis. Thank you Martina.

    From my point of view two remarks:
    1. Highly interesting would be data on member states delivering written observations in PIL cases, taking part in legal dialogue that way. Surprisingly, in that respect Austria seems to be very reluctant. A great pity, given that Austrian courts apply for instance the succession regulation as it is and do not look for reasons not to do so. On the other hand Spain is from my point of view a great “how to” example in that respect. Spanish government delivered written observations in most succession regulation cases known to me – open minded and showing great skills. The lecture was always an intellectual pleasure.

    2. The access to written opinions is something that really needs reform. From my point of view as a rule such opinions of public stakeholders, such as the Commission and member states, should be – at least for closed cases – publicly accessible. In Poland I apply for them under Polish freedom of information act in PIL cases interesting to me and obtain those filed by the Polish (and just the Polish) government. Similar possibility is needed on EU level so that the public has a chance to find out, which state delivered what arguments in a particular case, what was the position of the Commission, which stakeholders were open to which lobbying groups or followed which third-party interests ect. That transparency is definitely missing. We are not talking about private matters or private bodies and are talking about cases that shape our reality in many respects. The reason why the public is not able to get to know those statements made by public players is not understandable to me.

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