The Comdribus case recently decided by the CJEU (C-371/24, 19 March 2026) concerned the systematic collection of biometric data from persons suspected of having committed a criminal offence but ultimately not convicted. The case presents some striking similarities with S. and Marper v. the United Kingdom, decided by the ECtHR almost twenty years earlier (30562/04 and 30566/04, 4 December 2008), making a comparison between the two cases particularly interesting.

Both cases indeed raised similar legal questions. While both European Courts concur in rejecting the systematic collection or retention of such data, their focus is different: the CJEU mainly addresses the selection of the data concerned, whereas the ECtHR focuses on their use.

The CJEU indeed requires, in substance, that the collection of such data should, in each individual case, be “strictly necessary”. This must be justified by a sufficient statement of reasons, relying on specific and concrete purposes defined, in an appropriate and sufficiently precise manner, by national law. The ECtHR, for its part, found that the blanket and indiscriminate nature of the powers of retention at stake failed to strike a fair balance between the competing public and private interests (§ 125).

The facts

In S. and Marper, the applicants had been arrested and had their fingerprints and DNA taken. One was acquitted; the proceedings against the other were discontinued. Yet the authorities refused to destroy their fingerprints, cellular samples and DNA profiles. The Grand Chamber of the ECtHR held that the blanket and indiscriminate retention of data relating to persons who had not been convicted failed to strike a fair balance between the public interest in crime prevention and the applicants’ right to respect for their private life. There had therefore been a violation of Article 8 of the Convention (right to private life).

The facts in Comdribus were rather similar. HW was suspected of having committed criminal offences and, during the investigation, refused to have his fingerprints and photograph taken. He was ultimately acquitted of the underlying offences, but was convicted and fined for refusing the collection of his identification data.

There are, however, some differences between the two cases. While S. and Marper concerned the retention of personal data – the biometric and genetic material had already been collected and was retained after acquittal or discontinuance – Comdribus concerns the collection of personal data (fingerprints and photographs), which was refused by the person suspected of the offences. Comdribus also concerned the question whether a person may be prosecuted for such a refusal even if the underlying offence ultimately does not result in prosecution or conviction. The CJEU answered in the affirmative, but only where the envisaged collection itself complied with EU data-protection requirements and the penalty was proportionate.

Similar criteria

The two cases also operate within different legal frameworks: Article 8 of the Convention in S. and Marper and, in Comdribus, the much more detailed requirements of Directive 2016/680 (on the protection of natural persons with regard to the processing of personal data by competent authorities for the purposes of prevention, investigation, detection or prosecution of criminal offences or the execution of criminal penalties, and on the free movement of such data), particularly Article 10 on sensitive personal data, read in conjunction with Articles 4(1)(a) to (c) and 8 of the Directive and Articles 7, 8, 47 and 49 of the EU Charter.

Despite their different legal frameworks, the two European Courts reach their conclusions by applying criteria that are, in many respects, similar.

Both European Courts indeed consider personal data to be particularly sensitive and therefore to require “rigorous” or “careful” scrutiny of their processing (S. and Marper, §§ 103–104; Directive, Article 10; Comdribus, § 28).

Both Courts also rely on broadly similar criteria with regard to these data, notably:

• the precise objectives and purposes of the processing;
• the type of biometric data concerned;
• the nature and gravity of the suspected offence;
• the strength of the suspicion;
• the age, profile and conduct of the person suspected, including his or her previous arrests or criminal history;
• other particular circumstances;
• the availability of independent judicial review; and
• particularly in S. and Marper, the duration of the storage of the data.

Consequently, both Courts reject the “blanket and indiscriminate” (S. and Marper, §§ 119, 125) or “indiscriminate and general” use of such data (Comdribus, §§ 36 and 51).

Different guiding principles

These criteria, however, are applied in light of different guiding principles.

In Comdribus, based on the wording of Article 10 of the Directive, the guiding principle is the “strict necessity” of the collection of the personal data concerned (§§ 26, 29, 32, 33 and 34), combined with the principle of data minimisation (§§ 26 and 32). Under this approach, the question is not simply whether the use of biometric data is useful for combating crime. Rather, the authorities must ask whether the specific purpose of the data collection could be achieved just as effectively through less intrusive means or through categories of data that are less sensitive.

Thus, strict necessity places the emphasis on the selection of the data. The question is: why do we need these particular sensitive data for this particular purpose? In this context, data minimisation requires the authorities to use no more sensitive data than is strictly necessary.

By contrast, in S. and Marper, the guiding principle is proportionality. It requires the retention of biometric data to strike a fair balance between the public interest in exploiting modern scientific techniques for the prevention and detection of crime and the individual’s private-life interests (§§ 107, 112, 118 and 125). By relying on proportionality, the ECtHR does not require the State necessarily to use the smallest possible amount of personal data, as the CJEU does. It requires, rather, that the use of such data remain proportionate to the legitimate aims pursued. In other words, having regard to the circumstances of the case, the public interest served by the retention of the data should not be allowed to unduly outweigh the interest of the person concerned in maintaining the confidentiality of his or her personal data.

Thus, proportionality places greater emphasis on the overall use of the data. It looks beyond the mere collection of sensitive personal data and asks whether the concrete modalities of their retention and future handling are fairly balanced against the individual’s fundamental rights.

Complementary approaches

Because of their different focuses, these two approaches would appear to be complementary rather than mutually exclusive. The result is a two-layered form of scrutiny.

First, under EU law, the collection of sensitive personal data must satisfy the particularly demanding requirement of strict necessity. Second, under Article 8 of the Convention, the handling of those data must remain subject to the broader requirements of proportionality and fair balance.

For national judges confronted with the increasingly extensive use of biometric data in criminal justice, the two lines of case-law should therefore be read together: strict necessity to determine whether the data should be collected at all; proportionality to ensure that, once collected, they are handled in a manner that respects the fair balance required by Article 8.

Over the past seven years, more than 100 posts comparing the case-law of the European Court of Human Rights and the Court of Justice of the European Union have been published on this blog. To facilitate their consultation and help draw broader conclusions about the interplay between the Convention and EU law, the document below brings these posts together and organises them into the following thematic areas:

• Scope of the Convention and EU Law
• Rule of law and judicial independence
• Criminal procedure
• Judicial cooperation and mutual recognition
• Asylum, migration and international protection
• Privacy, data protection and personal identity
• Fundamental rights and equality
• Family, children and personal status
• Human dignity, living conditions and detention
• Environment, society and emerging challenges

This classification, which will be regularly updated, provides a broad overview of major developments which have shaped the relationship between these two European sources of law over the past seven years in each of these areas.

One of the main lessons emerging from this overview is that the interaction between Strasbourg and Luxembourg has not been uniform. The picture is nuanced and contrasted, marked by both convergences and divergences (for a descrition of the latter, see Trends 2021-26).

In this respect, the reality of the case-law developments does not always correspond to the frequently expressed assumption that the relationship between the Convention and EU law is characterised solely by harmony. The approaches taken by the two European courts sometimes reinforce one another and sometimes point in different directions, but they are rarely without mutual implications.

Against this background, one of the key challenges remains preventing the fragmentation of fundamental rights protection in Europe. Meeting that challenge requires a holistic approach: one that is attentive to significant differences where they exist, while ensuring that such differences do not weaken the overall effectiveness and coherence of European fundamental rights protection.

This thematic classification aims to assist judges, practitioners, researchers and students in navigating this rich and evolving body of case law.

It also features on top of recent case-law.

AW ‘T’ (4.9.2025, C-225/22) is another ruling by the CJEU on the rule-of-law crisis in Poland and the consequences to be drawn of the fact that, because of serious flaws in the procedure for the appointment of its members, the Chamber of Extraordinary Review and Public Affairs (CERPA) of the Polish Supreme Court cannot be regarded as an independent and impartial court previously established by law (see, among others, Krajowa Rada Sądownictwa). This time, the issue was about the effects of a decision by the CERPA upholding an extraordinary appeal lodged by the Prosecutor General.

The facts of the case can be summarized as follows. In 2004, AW ‘T’ filed a lawsuit against other companies claiming infringement of industrial property rights and unfair competition related to crossword puzzle magazines. After years of litigation, the Cracow Court of Appeal issued a final judgment in 2006. However, in 2020, the Prosecutor General filed an extraordinary appeal against the 2006 judgment, arguing procedural violations. The CERPA upheld the appeal in 2021, overturned the 2006 judgment, and referred the case back to the Court of Appeal for re-examination. The Court of Appeal referred the matter to the CJEU, seeking clarification on whether EU law allowed it to disregard the CERPA’s decision because of the serious flaws in the procedure which had led to the appointment of its members, thus raising doubts about its independence.  

In essence, the CJEU ruled that the principle of the primacy of EU law requires national courts to disregard national rules or decisions that conflict with EU law, including those of constitutional courts. Consequently, decisions by judicial bodies which do not meet the EU law requirements of independence, impartiality, and lawful establishment must be regarded as null and void by lower courts. Thus, the Cracow Court of Appeal should assess, in light of the criteria listed by the CJEU, whether the CERPA meets these requirements. If not, it is prevented under EU law from carrying out the re-examination ordered by the CERPA.

Interestingly, in Wałęsa v. Poland (23.11.2023, 50849/21), the ECtHR also had to deal with an extraordinary appeal lodged by the Polish Prosecutor General before the CERPA. This time, the CERPA had reversed a Court of Appeal judgment in favour of the applicant in a defamation case and had dismissed the latter’s claim. The applicant is a former leader of the “Solidarity” (Solidarność) trade union, a former President of Poland (from 1990 to 1995) and laureate of the 1983 Nobel Peace Prize.

AW ‘T’ and Wałęsa v. Poland thus provide a good opportunity to compare the Luxembourg and Strasbourg approaches on the legal consequences of the CERPA not being an independent and impartial court, which is an essential issue in the context of the rule-of-law crisis in Poland, with implications for similar constellations in other European countries.

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A first observation in this context is the consensus between the two European Courts on the fact that the CERPA lacks the necessary independence and impartiality for it to be considered a proper court for the purposes of the Convention and EU law.

In AW ‘T’, the CJEU recalled its ruling in Krajowa Rada Sądownictwa (C-718/21, 21.12.2023) in which it explicitly followed the conclusion reached by the ECtHR in Dolińska-Ficek and Ozimek v. Polandto the effect that because of the manner in which its members had been appointed, the CERPA could not have the status of an independent and impartial tribunal previously established by law, for the purposes of the second subparagraph of Article 19(1) TEU, read in the light of the second paragraph of Article 47 of the EU-Charter (§ 49).

In Dolińska-Ficek and Ozimek v. Poland, the ECtHR indeed concluded as follows:

“The breaches of the domestic law that [the ECtHR] had established, arising from non-compliance with the rule of law, the principle of the separation of powers and the independence of the judiciary, inherently tarnished the impugned appointment procedure. A procedure for appointing judges disclosing undue influence of the legislative and executive powers on the appointment of judges was per se incompatible with Article 6 § 1 of the Convention and, as such, amounted to a fundamental irregularity adversely affecting the whole process and compromising the legitimacy of a court composed of the judges so appointed. In sum, the breaches in the procedure for the appointment of judges to the CERPA of the Supreme Court were found to have been of such gravity that they impaired the very essence of the applicants’ right to a ‘tribunal established by law.’” (§§ 348-350)

Consequently, according to the CJEU, the competent panel of the CERPA had not met the requirements of effective judicial protection, as prescribed by the above provisions. Its composition was “such as to give rise to reasonable doubts, in the minds of individuals, as to the imperviousness of those judges and the panel in which they sit to external factors, in particular the direct or indirect influence of the national legislature and executive and their neutrality with respect to the interests before them. Those factors were thus capable of leading to a lack of appearance of independence or impartiality on the part of those judges and that body likely to undermine the trust which justice in a democratic society governed by the rule of law must inspire in those individuals” (§ 50).

Indeed, the presence, in the judicial body concerned, of a single judge appointed in such circumstances is sufficient to deprive that body of its status as an independent and impartial tribunal previously established by law (§ 57).

The remarkable consequence drawn from this conclusion by the CJEU is that, having regard to the primacy of EU law, the Court of Appeal should disregard, as being null and void, the decision by the CERPA ordering the Court of Appeal to re-examine the case in which the same Court of Appeal had already handed down a final judgment, regardless of the fact that this decision had the force of res judicata.

Accordingly, there was no need for the CJEU to engage in an assessment of the extraordinary appeal as such, as the decision of the CERPA to uphold it was null and void and could be disregarded. That was already the end of the story for the CJEU.

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Not so in Wałęsa v. Poland. The res judicata at stake here was not, as in AW ‘T’, the one attaching to the decision of the CERPA but the one attaching to the final judgment of the Court of Appeal which was set aside by the CERPA. Thus, the issue before the ECtHR was not only, as for the CJEU, the independence and impartiality of the CERPA, but whether there had been an abuse of the extraordinary appeal by the CERPA, making that appeal an ordinary appeal in disguise.

This difference has everything to do with the different position of the ECtHR and the different timing of its intervention in the judicial process, as pertinently observed by Advocate General Spielmann in paragraph 82 of his Opinion in AW ‘T’:

“The role of the Court of Justice when giving a preliminary ruling is to give national courts ex ante indications on how to apply EU law and not to determine ex post the existence of an infringement in a specific case, as is the case with the European Court of Human Rights. Thus, with regard to the requirements relating to an independent and impartial tribunal previously established by law, the Court has entrusted the national courts, as ordinary courts operating under EU law, with the task of monitoring compliance with those requirements and, where necessary, restoring the effectiveness of judicial protection in the Member States concerned.”

In other words, in AW ‘T’, the preliminary ruling by the CJEU disqualifying the CERPA prevented, at the level of the Cracow Court of Appeal, the extraordinary appeal from having any effect. By contrast, in Wałęsa v. Poland, the extraordinary appeal led to a judgment by the CERPA overturning the final judgment of the Court of Appeal and dismissing the applicant’s claims. The ECtHR was therefore called on to rule on the use and the effects of the extraordinary appeal in this case.

The ECtHR did not prohibit in the abstract any use of extraordinary appeals. Neither did it consider the composition of the CERPA as automatically entailing an abusive use of an extraordinary appeal. Rather, the flawed composition of the CERPA was only one aspect to be taken into account by the ECtHR, next to other criteria such as the public bodies authorised by law to lodge an extraordinary appeal, the grounds for lodging an extraordinary appeal, the time-limits for lodging an extraordinary appeal and the powers and characteristics of the adjudicating body (§§ 228-239).

In light of these criteria, the ECtHR found that the extraordinary appeal procedure as currently operating in Poland was incompatible with the fair trial standards and the principle of legal certainty under Article 6 § 1. This was because the circumstances of the case indicated an abuse of the extraordinary appeal by the State authority in pursuance of its own political opinions and motives. Accordingly, the ECtHR found no circumstances of a substantial and compelling nature that would justify the departure from the principle of res judicata in respect of the overturned judgment (§§ 254-255).

However, in contrast with the CJEU judgment in AW ‘T’, where the overturned final judgment was protected in the end, the judgment in Walesa v. Poland does not (yet) have the effect of restoring the overturned judgment.

It may nonetheless have a wider impact, since in view of the systemic nature of the violations found, the ECtHR decided to apply the pilot-judgment procedure (Rule 61 of the Rules of Court) as well as Article 46 of the Convention. Under the latter provision, the ECtHR indeed gave rather clear indications on the measures to be taken by the Polish government in order to remedy the situation on a larger scale, under the supervision of the Committee of Ministers of the Council of Europe (§§ 328-332).

This approach resulted from the fact that, in the ECtHR’s opinion, the violations found of Article 6 § 1 of the Convention originated in the interrelated systemic problems connected with the malfunctioning of domestic legislation and practice caused by several factors, including (a) a defective procedure for judicial appointments involving the National Council of the Judiciary, (b)  the resulting lack of independence on the part of the CERPA, (c)  the exclusive competence of the CERPA in matters involving a plea of lack of independence on the part of a judge or a court, (d)  the defects of the extraordinary-appeal procedure, and (e) the exclusive competence of the CERPA to deal with extraordinary appeals.

Interrestingly, the deficiencies thus identified to a large extent stem from the Polish laws which, in Commission v. Poland (Indépendance et vie privée des juges) (5.6.2023, C-204/21), the CJEU found in infringement proceedings to be in breach of EU law. One may therefore expect, as in the cases of Ilva and Cordella (see Two Courts, Two Paths: Comparing Europe’s Environmental Jurisprudence), some “synergies” between the European Commission and the Committee of Ministers of the Council of Europe in their efforts to bring the Polish judiciary in line with their common European standards.

Meanwhile, on 17 November 2025, the processing of currently about 1100 applications pending before the ECtHR concerning the “rule-of-law crisis” in Poland has been further adjourned until 23 November 2026, at the request of the Polish government, to give it more time to adopt general measures following the Wałęsa v. Poland pilot judgment (see the press release to that effect).

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When asking what the bottom line of the above considerations is, the following considerations come to mind.

1. Both European Courts are determined to fight populist agendas aiming at weakening the rule of law and judicial independence. They agree on the substance of the requirements which these values entail (on this, see also Populism on Trial: The European Courts’ Response to a Common Challenge).
2. The AW ‘T’ ex ante approach seems like a quick fix, protecting the res judicata of judgments being challenged through extraordinary appeals. From an applicant’s perspective it represents a preventive and therefore higher protection standard, which is entirely compatible with the Convention (see Art. 53). It may however leave the national judges applying the AW ‘T’ doctrine and disregarding judgments of a higher court in a somewhat delicate, unprotected position in the Polish judiciary.
3. By contrast, the Strasbourg ex post approach is slower but more comprehensive, thus benefiting a greater number of victims of the abuse of the extraordinary appeal. Indeed, 1100 applications concerning this systemic problem are currently pending before the ECtHR. However, this approach is also requiring a higher level of cooperation by the domestic authorities.
4. Both approaches in the end reinforce each other and are therefore to be welcomed.

Within a single month, both the European Court of Human Rights (ECtHR) and the Court of Justice of the European Union (CJEU) – acting through their Grand Chambers – issued judgments regarding dispute resolution in professional sports. These cases focused on the roles played by the Court of Arbitration for Sport (CAS) and the Swiss Federal Supreme Court (FSC).

In Semenya v. Switzerland (10934/21, 10.7.2025), the ECtHR adjudicated the case of an international-level South-African athlete who complained about a set of regulations issued by World Athletics (“the DSD Regulations”) requiring her to decrease her natural testosterone level in order to be allowed to take part in international competitions in the female category.

Royal Football Club Seraing (C-600/23, 1.8.2025), decided by the CJEU, concerned a Belgian football club which had concluded financing agreements with a Maltese company. The Fédération internationale de football association (FIFA) found these agreements to be in breach of the prohibition on third parties holding players’ economic rights and therefore imposed several sanctions on the club.

Pursuant to the regulations applicable to international sports competitions, which establish the CAS as having mandatory and exclusive jurisdiction in respect of disputes arising in this area, both cases were first brought before the CAS, the awards of which were subsequently challenged, by way of a civil-law appeal, before the Swiss Federal Supreme Court, which dismissed both appeals. In both cases, the review by the FSC was limited to assessing whether the CAS award was “incompatible with public policy”, a concept which under Swiss law is even more restrictive than that of arbitrariness (Semenya, § 226).

In Semenya, the ECtHR found inter alia that the FSC had breached Article 6 § 1 of the Convention (right to a fair trial). Because of its proximity with RFC Seraing, this finding will be the focus of the following developments.

In RFC Seraing, the CJEU ruled, in substance, that in circumstances as in the case at hand, where the dispute is linked to the pursuit of a sport as an economic activity, no authority of res judicata and no probative value could be conferred within the territory of a Member State on an award made by the CAS.

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With the two European Courts pronouncing upon the same international arbitration system – one that plays an important role in the world of international sports – the question arises as to what these rulings have in common, and how domestic courts should handle them.

A first common feature of these two rulings is the understanding shown for the particularities of litigation in international sports, which may justify certain restrictions on the common procedural rights (Semenya, §§ 195-199; RFC Seraing, § 84). However, there are limits to these restrictions, not least because of the structural imbalance which often exists between sportspersons and the bodies which govern their respective sports, and because these sportspersons have no choice other than submitting to the compulsory arbitration of the CAS. It is on the definition of these limits that the two European Courts follow different approaches. While the Luxembourg approach is more formal, the Strasbourg approach is more substantial.

The CJEU draws the line where matters relating to EU public policy are involved. These matters include the competition rules and the freedoms of movement (§§ 88-89). I such cases, the second sub-paragraph of Article 19(1) TEU, read in conjunction with Article 267 TFEU and Article 47 of the EU-Charter, requires full respect of the right to an effective judicial review. In concrete terms, this means that any domestic court of a Member State called on to give effect to an arbitration award such as the one by the CAS in the present case, must review that award for consistency with EU public policy and have the possibility to refer questions for a preliminary ruling by the CJEU, pursuant to Article 267 TFEU.

By contrast, the judgment of the ECtHR, which is directly reviewing the judgment of the FSC, follows a more substantial approach. Considering the case under Article 6 § 1 of the Convention, the ECtHR first notes the nature and importance of the “civil rights” invoked by the applicant, which are in fact fundamental rights, notably the rights to privacy, bodily integrity and dignity (§§ 215, 217).

This fact, in addition to the compulsory but private nature of the arbitration at stake, along with the restrictions it imposed on the rights being invoked, lead the ECtHR to hold that Article 6 § 1 required the FSC to carry out a “particularly rigorous examination” (§ 216) and an in-depth review (§ 238) of the civil-law appeal lodged with it by the applicant. Since the FSC failed to do so in respect of some key arguments of the applicant, even though the CAS itself had expressed serious concerns as regards some of the applicable DSD Regulations, the ECtHR concluded that before the SFC Ms Semenya had not benefitted from the safeguards provided by Article 6 § 1 (§ 238).

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What should be retained from this comparison?

The Luxembourg approach is limited in scope, as it applies only when a) EU law applies, b) the dispute is linked to the pursuit of a sport as economic activity, and c) matters relating to EU public policy are at stake. But when that is so, it requires full respect of the right to an effective judicial review, regardless of the concrete issues. To this extent, the Luxembourg approach is more formal but at the same time more comprehensive and more conducive to legal certainty.

By contrast, the Strasbourg approach is not limited in scope and more substantial, as it takes the importance and weight of the issues at stake before the CAS and the FSC as criterion and justification of the requisite intensity of the FSC’s scrutiny. To this extent, it is more facts-based, more selective and less conducive to legal certainty. The focus is on the essential issues in each case, which may vary in light of the concrete circumstances.

What does that mean for domestic judges? The good news is that while different, these two approaches seem compatible with each other. This is because, when applicable, the Luxembourg approach requiring full respect of the right to an effective judicial review would appear to represent a higher standard than the Strasbourg “particularly rigorous examination”, the scope and intensity of which might moreover vary from case to case. Yet, it is well-known that the Strasbourg standard is only a minimum which may be raised (Art. 53 of the Convention).

The bad news, on the other hand, is for the FSC who is being told by RFC Seraing that however compliant with Article 6 § 1 of the Convention its review of CAS awards might be in the future, it cannot legally replace within the territory of the European Union a review by a court of a Member State authorised to make a reference to the CJEU for a preliminary ruling.

See also: European Case-Law on Sport: Challenges for National Judges