62023CC0679
OPINION OF ADVOCATE GENERAL
ĆAPETA
delivered on 12 June 2025 (
1
)
Case C‑679/23 P
WS,
WT,
WY,
WZ,
YA,
YB
v
European Border and Coast Guard Agency (Frontex)
(Appeal – Area of freedom, security and justice – Policies on border checks, asylum and immigration – Regulation (EU) 2016/1624 – European Border and Coast Guard Agency (Frontex) – Joint return operation – Alleged breach of fundamental rights – Non-contractual liability – Causal link)
I. Introduction
1.
A family of Syrian Kurds was returned by plane from Greece to Türkiye in a joint return operation coordinated by Frontex. (
2
)
2.
They now ask the EU Courts, on the basis of Article 268 TFEU and the second paragraph of Article 340 TFEU, to order Frontex to pay them damages. They claim that the material and non-material damage they suffered were caused by Frontex’s illegal action – or more precisely, inaction – before, during and after that return operation, which infringed a number of their fundamental rights.
3.
Can the European Union incur liability for damages for unlawful actions and/or omissions of Frontex during a joint return operation? In principle, such operations are the primary responsibility of the Member State from which the returns are carried out (‘the host Member State’), and Frontex has a supporting role in the preparation, organisation and coordination of such operations. This case therefore raises the question as to whether Frontex has concrete obligations in such operations, and if so, which of those obligations, if infringed, may lead to the European Union’s liability for damages, notwithstanding the primary responsibility of the host Member State for such operations.
4.
However, this case has reached the Court of Justice on appeal against the General Court’s judgment at first instance. (
3
) The General Court dismissed the action of the Syrian family on the basis of the lack of a causal link between the alleged illegal conduct of Frontex and the damage suffered. Thus, the General Court did not assess the other conditions for incurring non-contractual liability, namely those relating to unlawfulness and damage. (
4
)
5.
Consequently, the assessment by the Court of Justice in the present case is limited to issues ruled on by the General Court. Nevertheless, the Court of Justice has the opportunity to clarify whether Frontex could incur liability for the breach of fundamental rights in joint return operations, as well as to develop its case-law on causal link. (
5
)
II. Events leading to the proceedings before the General Court
6.
The applicants, WS and Others, are a family of six Syrian nationals who are ethnic Kurds, consisting of two parents and four children.
7.
On 9 October 2016, they arrived on the island of Milos (Greece) among a group of 114 refugees. (
6
)
8.
On 14 October 2016, they were transferred to the Reception and Identification Centre in Leros (Greece), where they formally declared their interest in applying for international protection. (
7
)
9.
On 19 October 2016, according to the applicants, the Greek police transported them, along with a number of other Syrian nationals, from the Leros hotspot to the Leros police station. They were told that they were being transferred to Athens (Greece) the next day.
10.
On 20 October 2016, they were taken by plane to Adana (Türkiye) in a joint return operation of Greece and Frontex (‘the joint return operation’). (
8
) The applicants were then transferred to a temporary reception centre in south-eastern Türkiye.
11.
During the return flight, the applicants claim that they were each seated next to an escort officer and not allowed to communicate. According to the applicants, they still believed that they were being transferred to Athens; it was only when they disembarked from the plane and were handed over to Turkish officials that they realised that they had been brought to Türkiye instead.
12.
On 2 November 2016, the Turkish authorities issued the applicants with temporary protection documents and a temporary travel permit. The applicants left the reception centre and moved to the village of Saruj (Türkiye), where they rented a house and bought furniture. However, according to the applicants, they later moved to Erbil (Iraq) because they feared that the Turkish authorities would return them to Syria. They have resided there ever since.
13.
On 4 January 2017, the applicants lodged a complaint with Frontex regarding the joint return operation. They claimed that their fundamental rights had been infringed due to the assistance of Frontex in that operation.
14.
On 15 February 2017, the Frontex Fundamental Rights Officer (‘FRO’) informed the applicants that their complaint was admissible, and had been forwarded to the Executive Director and to the Greek Ombudsman as the competent national authority to handle fundamental rights-related complaints against border guard authorities in Greece.
15.
After a series of communications between the FRO and the applicants regarding the progress of their complaint, on 7 June 2017, the applicants were informed that their complaint had been forwarded to the Greek police, as the Greek Ombudsman did not have a mandate to review that complaint.
16.
On 17 July 2018, the applicants lodged a second complaint with Frontex due to the lack of progress on the first complaint.
17.
On 9 August 2018, Frontex informed the applicants that the second complaint was admissible and joined to their first complaint.
18.
After a series of further communications between the FRO and the applicants regarding the progress made on their complaints, on 25 November 2019, the FRO informed them that the Greek authorities had completed their internal disciplinary investigation and issued a final report, according to which no disciplinary liability was established.
19.
On 6 October 2020, the FRO issued a final report on the two complaints and closed the case. According to that report, the Greek authorities acted contrary to the applicants’ fundamental rights as guaranteed by Articles 18, 19, 24, 41 and 47 of the Charter of Fundamental Rights of the European Union (‘the Charter’). That report also indicated that Frontex had complied with its obligations by following up on the matter and liaising directly with the Member State concerned, and had undertaken initiatives to ensure that legal requirements were in place when implementing returns in the future. (
9
) However, there was no mention of Frontex’s possible liability in that report.
20.
By emails of 8 and 12 October 2020, the applicants queried, in particular, that that report did not address Frontex’s involvement in the joint return operation, nor did it address the second complaint against Frontex.
21.
By email of 13 October 2020, the FRO responded that Frontex had complied with its obligations concerning the handling of their complaints. That email indicated, in particular, that, in accordance with the relevant rules, Frontex followed up with the Greek authorities at regular intervals, and that the complaints mechanism is of an administrative nature such that there were no further remedies to challenge the findings and follow-up of the complaints, but that redress may be sought before the EU institutions.
22.
In the meantime, on 19 April 2017, the applicants lodged an action against Greece before the European Court of Human Rights (ECtHR) relating to the same joint return operation, alleging violations of Articles 3 and 13 of the European Convention on Human Rights (ECHR). The case was removed from the ECtHR’s register after the parties reached a friendly settlement. (
10
) Greece agreed to pay EUR 12500 for material and non-material damages per applicant, or EUR 75000 total, plus EUR 1500 for costs and expenses.
III. Proceedings before the General Court and the judgment under appeal
23.
On 20 September 2021, the applicants brought an action for damages before the General Court, based on Article 268 TFEU, the second paragraph of Article 340 TFEU and Article 60(3) of Regulation 2016/1624, (
11
) requesting compensation for damage suffered by them due to alleged unlawful conduct committed by Frontex before, during and after the joint return operation.
24.
The applicants claimed that Frontex had failed to comply with its obligations under Articles 16, 22, 25, 26, 28, 34 and 72 of Regulation 2016/1624, along with steps 1 to 5 of the Standard Operating Procedure (
12
) and Article 4 of the Code of Conduct, (
13
) which infringed their fundamental rights as guaranteed by Articles 1, 4, 18, 19, 24, 41 and 47 of the Charter.
25.
The applicants advanced eight pleas in law. By their first, second and third pleas, they accused Frontex of failing to take measures to prevent a breach of their fundamental rights in the preparation of the joint return operation. By their fourth, fifth and sixth pleas, they complained that Frontex had failed to ensure that the joint return operation was conducted in a way capable of safeguarding their fundamental rights during that operation. By their seventh and eighth pleas, they claimed that Frontex had failed to take proper measures to evaluate the joint return operation and to handle their complaints after that operation.
26.
The applicants asked that the General Court award them damages for the breaches at issue, claiming that the conditions to engage EU non-contractual liability were met. They thereby requested the General Court to order Frontex to pay them compensation in the amount of EUR 96 212.55 in respect of material damage and EUR 40000 in respect of non-material damage, plus interest. (
14
) They also claimed that Frontex should be ordered to pay the costs.
27.
Frontex contended that the action should be rejected and that the applicants should be ordered to pay the costs.
28.
By the judgment under appeal, the General Court dismissed the action in its entirety.
29.
First, the General Court found that certain documents produced by the applicants for the first time at the stage of the reply or before the close of the oral stage of the procedure were inadmissible because they were submitted out of time without justification (paragraphs 41 to 46 and 49 to 51 of the judgment under appeal).
30.
Second, the General Court decided to first assess the condition of causal link between the alleged illegal conduct and the damages claimed (paragraph 55 of the judgment under appeal). It held that the applicants had not demonstrated a sufficiently direct causal link between the damage invoked and the conduct of which Frontex was accused (paragraph 71 of the judgment under appeal).
31.
The General Court reached that conclusion based on two lines of reasoning. In the first line of reasoning (paragraphs 62 to 66 of the judgment under appeal), it started by noting that the applicants’ arguments were based on the incorrect premiss that, but for Frontex’s alleged failures to fulfil its obligations relating to the protection of fundamental rights in the context of the joint return operation, they would not have been unlawfully returned to Türkiye and would not have suffered the damage invoked (paragraph 62 of the judgment under appeal).
32.
In that respect, the General Court considered that, under Article 34(1) of Regulation 2016/1624, Frontex must ensure the protection of fundamental rights only in the performance of its tasks (paragraph 63 of the judgment under appeal). It continued by stating that, under Article 27(1)(a) and (b) and Article 28(1) of that regulation, Frontex’s task as regards return operations is only to provide technical and operational support to Member States, and not to enter into the merits of return decisions. That latter assessment, as is clear from Directive 2008/115/EC, (
15
) falls within the competence of the Member States alone (paragraph 64 of the judgment under appeal). Likewise, the General Court stressed that, in accordance with Directive 2013/32/EU, (
16
) the Member States alone are competent to examine applications for international protection (paragraph 65 of the judgment under appeal).
33.
The General Court therefore held that, since Frontex has no competence either as regards the assessment of the merits of return decisions or as regards applications for international protection, a direct causal link could not be established between the conduct and the damage complained of. It added that it is also clear from Article 42(1) and (2) of Regulation 2016/1624 that that damage is, in principle, the sole responsibility of the host Member State (paragraph 66 of the judgment under appeal).
34.
In the second line of reasoning (paragraphs 67 to 70 of the judgment under appeal), the General Court found that the damage alleged was not a direct consequence of Frontex’s alleged unlawful conduct, but instead was the result of the choice the applicants had made. Specifically, according to the General Court: (i) the material damage linked to the expenses incurred in Türkiye was a consequence of their choice not to comply with the instructions on the temporary travel permit issued by the Turkish authorities; (ii) the material and non-material damage linked to the journey to Iraq and settling there were also a consequence of their own decision and could not be regarded as resulting directly from Frontex’s conduct; and (iii) the material damage linked to the legal aid costs in connection with the complaints against Frontex was the result of their decision to engage legal representation, which was not mandatory.
35.
Consequently, and in view of the cumulative nature of the conditions for incurring EU non-contractual liability, the General Court dismissed the case without analysing the other conditions for incurring non-contractual liability (paragraph 72 of the judgment under appeal).
IV. Procedure before the Court of Justice
36.
By their appeal lodged on 14 November 2023, WS and Others, as the appellants, request that the Court of Justice set aside the judgment under appeal, refer the case back to the General Court for determination or, in the alternative, give judgment itself and declare the action well founded. They also request that the Court of Justice order Frontex to pay the costs.
37.
In its response lodged on 7 February 2024, Frontex requests that the Court of Justice dismiss the appeal and order the appellants to pay the costs.
38.
The appellants and Frontex also lodged a reply and a rejoinder on 18 April 2024 and 27 May 2024, respectively.
39.
A hearing was held on 4 February 2025 at which both parties presented oral argument.
V. Analysis
40.
The appellants raise four grounds of appeal. The first ground alleges mischaracterisation of the action as a challenge to the decision to refuse them international protection or to the (implied) return decision. The second ground alleges that, due to such mischaracterisation, the General Court failed to assess the appellants’ arguments that Frontex’s illegal conduct caused their damage and thus that the General Court wrongly found that there was no causal link. The third ground alleges incorrect assessment that the causal link between Frontex’s conduct and the damage suffered by the appellants was broken by the appellants’ own choices. The fourth ground alleges misinterpretation of the General Court’s Rules of Procedure in declaring certain documents inadmissible.
41.
I will start my analysis by assessing the arguments raised by Frontex contesting the admissibility of the present appeal (A). I will then analyse the first two grounds of appeal together (B), before turning to the third (C) and fourth (D) grounds of appeal.
A.
Admissibility
42.
Frontex essentially challenges the admissibility of the present appeal on four grounds.
43.
First, Frontex contends that the first three grounds of appeal are inadmissible because they call into question the General Court’s factual findings, and in particular the existence of the return decision.
44.
Second, Frontex submits that the first three grounds of appeal are inadmissible in so far as they raise the joint and several liability of Frontex and Greece, which constitutes a new plea in law that had not been raised at first instance.
45.
Third, Frontex complains that the first and second grounds of appeal are inadmissible for failure to indicate sufficiently precisely the contested elements of the judgment under appeal.
46.
Fourth, Frontex questions the appellants’ interest in contesting the judgment under appeal, given that they have already obtained compensation from Greece in their action before the ECtHR (see point 22 of this Opinion).
47.
The appellants argue that the present appeal is admissible and that Frontex’s arguments should be rejected.
48.
I agree.
49.
First, by the first three grounds of appeal, the appellants do not seek a new assessment of the facts and evidence, but instead seek to challenge the legal characterisation applied by the General Court on the basis of which that Court decided that there was no direct causal link between the conduct of Frontex and the damage alleged.
50.
In that respect, the appellants argue that the General Court’s assumption that the action concerned a challenge to the return decision is an assumption of law, not of fact. They claimed at first instance that a return decision did not exist, which is what Frontex was under an obligation to verify. The General Court’s decision not to assess the existence of a return decision is thus the result of a legal error. Likewise, the appellants argue that the General Court failed to assess other relevant facts – for example, whether a Frontex staff member was on board the return flight or whether Frontex had received a list of names of returnees from the Greek authorities – on account of the error of law consisting in the mischaracterisation of their action.
51.
Accordingly, the appellants do not ask the Court of Justice to establish those facts, but rather to find that the General Court should have done so. Additionally, the question whether legal representation was necessary is not a matter of fact, but involves a legal evaluation, which the appellants are entitled to challenge. The appellants’ arguments relating to facts are therefore arguments on points of law subject to review by the Court of Justice on appeal. (
17
)
52.
Second, the appellants’ arguments in the first three grounds of appeal relating to the joint and several liability of Frontex and Greece were not raised for the first time on appeal. It is apparent from the submissions of the parties before the General Court (
18
) that the appellants had relied on arguments that there is joint liability of Frontex and Greece in return operations, (
19
) such that each bears responsibility for its own conduct and for the damage caused to the appellants.
53.
Third, the first two grounds of appeal indicate precisely the contested paragraphs of the judgment under appeal and set out the reasons why those paragraphs are, according to the appellants, vitiated by an error of law, enabling the Court of Justice to understand which elements of the judgment under appeal are being challenged and to exercise its power of review of their lawfulness.
54.
Fourth, as affirmed at the hearing, the appellants had an interest when they brought their action, and that interest continues, since the amicable settlement with Greece did not extinguish their claim before the EU Courts. Thus, the objective pursued by this action to secure adequate compensation for the damage suffered in relation to Frontex has not been achieved. The fact that separate proceedings were brought before a different court by the appellants against Greece for alleged violations of different rules, namely the provisions of the ECHR, arising from the same joint return operation may have an impact, as indicated by the appellants, on the quantification of damages.
55.
Therefore, I consider that the present appeal is admissible.
B.
The first and second grounds of appeal
56.
By the first two grounds of appeal, which concern paragraphs 62 to 66 and 71 and 72 of the judgment under appeal, the appellants essentially claim that the General Court mischaracterised their arguments at first instance. This had the consequence that the General Court erroneously concluded that the existence of a causal link was not shown and therefore did not assess any of the eight pleas in law raised at first instance.
57.
The appellants contend that they claimed that Frontex caused them damage by infringing its own obligations, and not by infringing the obligations that can only be attributed to Member States. Thus, their action at first instance was directed at Frontex’s performance of its obligations under Regulation 2016/1624 to guarantee respect for fundamental rights in the implementation of the joint return operation. However, the General Court instead construed that action as a challenge to the decision to refuse them international protection or to the (implied) return decision taken in respect of them by the Greek authorities. For that reason, the General Court failed to attribute the unlawful conduct to Frontex and assess whether a causal link existed between that conduct and the damage claimed. If the General Court had not mischaracterised their arguments, it would have assessed all eight pleas in law raised at first instance, each claiming a breach of different obligations that Frontex has under EU law which, according to the appellants, led to the breach of their fundamental rights and caused them damages. The appellants further assert that the General Court wrongly interpreted Article 42(1) and (2) of Regulation 2016/1624, since that provision is unrelated to Frontex’s liability for failure to comply with its obligations under that regulation.
58.
Frontex disputes those assertions and argues that the first two grounds of appeal should be rejected.
59.
To begin with, I consider that, in the contested part of the judgment under appeal, the General Court did not bring its reasoning to a conclusion. It did not explain how its findings – that Member States alone are competent for return decisions and applications for international protection – related to its conclusion regarding the lack of a causal link.
60.
In my view, that ambiguous part of the judgment under appeal can be understood in one of two ways. First, that judgment may be read as if the General Court misunderstood the appellants’ arguments at first instance in the sense that they were challenging the validity of the return decision, rather than Frontex’s omission in verifying whether a return decision existed at all. Second, that judgment may be read as if the General Court considered that Frontex could not incur liability for damages in so far as it merely supports return operations of Member States. Viewed in that way, the General Court implicitly held that the prohibition on Frontex to assess the merits of return decisions, as set out in Article 28(1) of Regulation 2016/1624, exempts it from verifying that a return operation concerns persons who are the subject of a return decision.
61.
If the first reading of the judgment under appeal is correct, the General Court erred in law by misapplying the notions of attribution and causation.
62.
The notion of causal link, on the one hand, answers the question of cause and effect, namely whether (in)action of a particular actor (cause) led to the damages sustained (effect). The notion of attribution, on the other hand, connects the unlawful conduct to the relevant actor. (
20
)
63.
If the claim brought before the General Court is that Frontex’s (in)action is the cause, the General Court cannot answer the question whether there is a link between that cause and the alleged damage by examining the (in)action of a different actor (here, Greece).
64.
In other words, to conclude that Frontex could not cause the damage claimed, the General Court would have had to start from the alleged (in)action of Frontex, and then conclude that that alleged unlawful conduct was not a sufficiently direct cause of such damage. It is true that the General Court could have reached the conclusion that Frontex could not have caused the damage at issue if it considered that verifying the existence of the return decision is not within Frontex’s competence. (
21
) That is what I propose as the second possible reading of the judgment under appeal. However, that is not what the General Court (at least not expressly) stated. Rather, it focused on the fact that the adoption of a return decision is within the competence of the Member States, and not of Frontex. The appellants, as they reiterated at the hearing before the Court of Justice, never disputed that point.
65.
Therefore, one possible conclusion is that the General Court confused attribution and causation in not linking the right conduct to the right actor and thus erroneously assessed the existence of the causal link. (
22
)
66.
However, as I explained, it is also possible that the General Court considered that Frontex does not have an obligation to verify whether the persons covered by the joint return operation are indeed returnees, in the sense that there is an enforceable return decision that concerns them. Thus, as the alleged unlawful conduct is not attributable to Frontex, the General Court could have logically concluded that there could not be a causal link between that conduct and the damage.
67.
If this second reading of the judgment under appeal is correct, it requires an answer to two questions. First, does Frontex have its own obligations under EU law during joint return operations, including the obligation to verify whether there exists a return decision in relation to each person placed on board the plane? Second, if Frontex has such an obligation, but Greece also has the same obligation, can Frontex incur liability for the entire amount of damage on its own? I will examine these two questions in turn.
1. Does Frontex have an obligation to verify under Regulation 2016/1624?
68.
The appellants argue that all of the damage they suffered stems from their inclusion in the joint return operation. Had Frontex carried out its obligation to verify whether there existed a return decision in relation to them, it would have found that there was none, and the appellants would have been excluded from that return operation. Therefore, the main cause of the damage they suffered is Frontex’s omission to verify the existence of the return decision by which it infringed their fundamental rights, including the principle of non-refoulement.
69.
It is therefore necessary to determine whether Frontex has such an obligation to verify under Regulation 2016/1624.
70.
To start with, it is undisputed that the Charter cannot of itself bestow any new powers or tasks on the European Union. (
23
)
71.
Therefore, as the General Court correctly pointed out in paragraph 63 of the judgment under appeal, Article 34(1) of Regulation 2016/1624 bestows on Frontex the obligation to guarantee the protection of fundamental rights only in the performance of its tasks under that regulation.
72.
That said, in the performance of its tasks, Frontex must ensure respect for fundamental rights. All EU institutions and bodies are bound by the Charter, by virtue of its Article 51(1), so that restatement of such an obligation in Article 34(1) of Regulation 2016/1624 is merely declaratory.
73.
Regulation 2016/1624 dealt with Frontex’s obligations in return operations in Article 28. Under its first paragraph, (
24
) Frontex provides the necessary assistance and ensures the coordination or organisation of return operations in accordance with Directive 2008/115.
74.
Directive 2008/115 prohibits returns without enforceable return decisions. (
25
) The purpose of insisting on a return decision serves, among other things, to ensure that the return would not be contrary to the principle of non-refoulement. (
26
)
75.
That is reflected in Regulation 2016/1624. Thus, Article 4(h) thereof provides that one of the components of European integrated border management is the ‘return of third-country nationals who are the subject of return decisions issued by a Member State’. (
27
)
76.
The concept of a ‘returnee’ in Article 2(13) of Regulation 2016/1624 also presupposes the existence of a ‘return decision’, which, according to Article 2(12) thereof, means an administrative or judicial decision or act, stating or declaring the stay of a third-country national to be illegal and imposing or stating an obligation to return that respects Directive 2008/115.
77.
Thus, it is possible to conclude that the intention of the EU legislature in Regulation 2016/1624 is that joint return operations coordinated and/or organised by Frontex can only involve persons who are subject to individual enforceable return decisions.
78.
By verifying that a return decision exists in relation to all persons covered by a joint return operation which it coordinates and/or organises, Frontex thus fulfils its obligation to ensure respect for fundamental rights, including the principle of non-refoulement, in the performance of its tasks, as required by Article 34(1) of Regulation 2016/1624.
79.
At the same time, such a verification is not contrary to Article 28(1) of that regulation, which provides that Frontex’s assistance does not include ‘entering into the merits of return decisions’. Verification of the existence of a return decision is not the same as the assessment of its content, and therefore does not conflict with the prohibition on entering into the merits of such a decision, which is the responsibility of Member States. (
28
)
80.
During the procedure before the Court of Justice, Frontex has not denied that its tasks include verification of the existence of return decisions. Nevertheless, Frontex claimed that it had fulfilled such an obligation in the context of the joint return operation, as it was in possession of the list of names which it received from the Greek authorities and which contained the appellants’ names. Frontex further contended that, taking into consideration the principle of sincere cooperation, it could only have questioned the regularity of that list if it were aware of factual circumstances that would point to the possibility that that document was erroneous, which was not the case here.
81.
The appellants claim, however, that the list at issue contained the names of persons who did not ask for asylum, and not the list of returnees, which, moreover, was wrong information in relation to them, as they expressed their intention to ask for asylum.
82.
That discussion, even if relevant for the establishment of Frontex’s liability, should have been conducted by the General Court as a matter of establishing the relevant facts. In the context of this appeal, what matters is that that discussion is not connected to the question whether a causal link could exist between Frontex’s omission to verify whether the appellants were returnees and the damage they suffered by being returned. As the General Court concluded that there is no causal link, it did not establish those relevant facts, which are pertinent to other conditions for liability. If Frontex can establish that it has done what was possible and sufficient to verify that the appellants were indeed returnees, there would not be a breach of its obligation, or such a breach would not be sufficiently serious. Therefore, that discussion concerns another condition for non-contractual liability, but is irrelevant for deciding on the existence of the causal link.
83.
To conclude, under Regulation 2016/1624, Frontex does have an obligation to verify whether a return decision exists in relation to all persons covered by a joint return operation, which is important for fulfilling its obligation to ensure respect for the principle of non-refoulement in the performance of its tasks. Frontex itself does not deny this. The General Court therefore erred in law when it found that there could be no causal link between the allegedly unlawful conduct of Frontex and the damage suffered by the appellants.
2. Is there joint and several liability of Frontex and the host Member State?
84.
In the second reading of the judgment under appeal, it is also possible that the General Court did not attribute the allegedly unlawful conduct to Frontex because it considered that Frontex and a Member State could not be jointly and severally liable for the same damage.
85.
In the scholarly literature, the notion of joint liability, which may also be referred to as shared or concurrent liability, generally denotes situations where both the European Union and the Member States incur liability for separate infringements of EU law causing a single harm. (
29
) Particular attention has been devoted to Frontex in that regard. (
30
) The notion of joint and several liability seems to express the idea that more than one actor can be liable for the same damage (hence the concept of shared or joint liability) together with the possibility that the person harmed may bring an action against any of those actors for the entire damage. (
31
)
86.
The appellants seem to use the notion of joint and several liability in that way. At the level of implementation of the joint return operation, according to them, both Frontex and Greece each have their own obligation to verify that there is a return decision before returning a person. A person wrongfully returned due to the omission to verify the existence of a return decision can claim damages either from Frontex or from a Member State. Indeed, in the current system of judicial protection in the European Union, an injured party cannot bring an action against both Frontex and a Member State in the same court, as different courts have jurisdiction to hear such claims.
87.
Article 5(1) of Regulation 2016/1624 provides that the European Border and Coast Guard – that is, Frontex and the Member States (
32
) – are to implement European integrated border management as a ‘shared responsibility’, while Member States are to retain primary responsibility for the management of their sections of the external borders. (
33
)
88.
Shared responsibility can lead to shared liability for damages. Whereas a Member State can be liable for any type of action or omission, Frontex can share liability only for those actions or omissions which are within the tasks bestowed on it by EU law. The possibility of shared liability is not just a theoretical academic discussion. This has potentially important implications not only for Frontex, whose powers increase with each amendment of the EU legislation that governs it, but also for a number of other EU agencies that carry out tasks in cooperation with the Member States.
89.
The Court of Justice considered that EU institutions could share liability with Member States already in its early case-law, such as Kampffmeyer and Others v Commission. (
34
) The recent judgment in Kočner v Europol (
35
) seems to have introduced some uncertainty whether shared responsibility can result in joint and several liability if such liability is not expressly provided for by EU legislation in a specific situation. In that latter judgment, the Court considered that Article 50 of Regulation (EU) 2016/794 (
36
) introduced joint and several liability of the European Union Agency for Law Enforcement Cooperation, known as Europol, and a Member State for unlawful data processing as a special rule which derogates from general non-contractual liability rules in that regulation. (
37
)
90.
In my understanding, by that judgment, the Court did not intend to establish that joint and several liability is an exception in situations in which Member States share responsibility for the same actions with EU institutions or bodies, which depends on such liability being provided for by EU legislation. Rather, the specificity of the rule in Regulation 2016/794, to which the Court referred, was that it introduced a two-stage mechanism, which relieved the individual from the obligation to attribute unlawful data processing to either Europol or a Member State, but made it sufficient to show that unlawful data processing had occurred. (
38
)
91.
In the present case, the situation differs from that in Kočner v Europol. Whereas the rule in that case was justified by the fact that it was impossible for an individual to establish whether unlawful data processing is attributable to Europol or to a Member State, in the present case, it is possible to attribute the same omission to both Frontex and Greece. Both have their own obligation under EU law not to allow the return of a person in relation to which there is no return decision. Had either Frontex or Greece carried out that verification, and on condition that there was indeed no return decision as claimed by the appellants, the appellants would have been excluded from the joint return operation. Therefore, the cause of the damage in this particular scenario could be attributed to both actors, as either of them could have prevented the damage from occurring.
92.
Does the fact that primary responsibility for returns lies with Member States prevent Frontex from also being held liable for the same omissions? If the Court were to adopt such an interpretation, Frontex could likely never be held liable for any unlawful actions or omissions during return operations, as similar obligations would also pertain to Member States. To my mind, that would unduly diminish the responsibility of Frontex and threaten the protection of fundamental rights.
93.
I am therefore of the view that, in situations in which both Frontex and Member States share obligations in joint return operations, Frontex can be held liable for damage caused by the breach of such obligations, even if a Member State can be liable in parallel for the same damage.
94.
That leads me to consider that the General Court was not correct in concluding that there could not be a causal link between Frontex’s omission to verify and the damages sustained by the appellants because the wrongful action could not be attributed to Frontex in situations in which it could be attributed to a Member State.
95.
It should be added that the General Court’s reliance on Article 42(1) and (2) of Regulation 2016/1624 is misconceived. As indicated by the appellants, that provision is concerned with specific wrongdoings of staff members in operational activities. It does not affect or have a bearing on Frontex’s own liability for breach of its obligations to ensure respect for fundamental rights under that regulation, as provided for in Article 60(3) thereof. (
39
)
96.
In summary, whether the first reading or the second reading of the judgment under appeal is correct, the General Court’s findings that there was no causal link between Frontex’s omissions and the damage sustained by the appellants is legally flawed.
97.
Therefore, I consider that the first and second grounds of appeal are well founded.
C.
The third ground of appeal
98.
By the third ground of appeal, which concerns paragraphs 66 to 72 of the judgment under appeal, the appellants essentially claim that the General Court erred in law by finding that the causal link was broken by the appellants’ own choices.
99.
The first part of that ground of appeal concerns the material and non-material damage relating to Türkiye and Iraq, whereas the second part of that ground of appeal concerns the material damage relating to the legal aid costs in connection with the complaints against Frontex. (
40
) I will deal with those two issues separately.
1. The causal link as regards the material and non-material damage relating to Türkiye and Iraq
100.
The General Court considered, in paragraphs 68 and 69 of the judgment under appeal, that the material and non-material damage relating to settling in Saruj (Türkiye), fleeing to Iraq and finally settling there, were caused by the appellants’ own choices, and not by Frontex’s conduct. There was therefore no link between Frontex’s conduct and the damages claimed. The appellants submit that those findings are vitiated by an error of law.
101.
As noted in the scholarly literature, there is a distinction between factual and legal causality. (
41
)
102.
When deciding about factual causality, courts ask whether the unlawful conduct is a conditio sine qua non for the damage claimed. That is often referred to as the ‘but for’ test. Applied at EU level, there is a causal link if, but for the conduct of the EU institution or body, the damage would not have occurred. Where the conduct consists in an omission, the question is whether the damage would not have occurred had the EU institution or body fulfilled its obligation as required by EU law. If the answer is in the affirmative, there is a factual causal link.
103.
Starting with paragraph 67 of the judgment under appeal, the General Court seems to have conducted its analysis based on the premiss that factual causality existed. If that was not so, then concluding, as the General Court did, that the causal link between Frontex’s conduct and the damage claimed was broken by the appellants’ choices would not make sense. Thus, the General Court’s reasoning presumes that Frontex’s omission to verify the existence of a return decision was the conditio sine qua non that led to the damage suffered by the appellants. Certainly, such a conclusion can only be reached if the return decision did not exist, a fact which was not established in the proceedings before the General Court. However, were that the case, the ‘but for’ test would be fulfilled. In other words, had Frontex carried out such a verification, it is possible that it would have found that a return decision did not exist and the appellants would not have been included in the joint return operation and, consequently, would not have sustained the damage invoked.
104.
The ‘but for’ test does not distinguish between different types of consequences; it does not ask whether the consequences are likely or unlikely, foreseeable or unforeseeable, immediate or remote. (
42
) Nevertheless, the legal systems of the Member States often limit factual causality by introducing additional requirements for incurring liability. That is generally referred to as legal causality.
105.
Courts, both at national level and at EU level, express those additional requirements by using different terminology and concepts. (
43
) Thus, the EU Courts have used, without explaining what they mean, expressions such as the damage flowing sufficiently directly from the unlawful conduct, a sufficiently direct causal nexus between the conduct and the damage, or that conduct is the determining cause of the damage. (
44
)
106.
In that light, the General Court observed, in paragraph 67 of the judgment under appeal, that ‘the mere fact that the unlawful conduct constituted a necessary condition (a condition sine qua non) for the damage to arise, in the sense that the damage would not have arisen in the absence of such conduct, is not sufficient to establish a causal link’. (
45
)
107.
The case-law of the Court of Justice has not used such phrasing. (
46
) Nevertheless, it seems that the Court also considers that the ‘but for’ test is not always sufficient for incurring liability. Thus, in a number of judgments, the Court has held that the principles common to the laws of the Member States to which the second paragraph of Article 340 TFEU refers cannot be relied upon to deduce an obligation on the European Union to make good every harmful consequence, even a remote one. (
47
)
108.
Therefore, even if Advocates General (
48
) and scholars (
49
) have noted that the EU Courts’ case-law on the assessment of the causal link is not systematic and necessarily proceeds on a case-by-case basis, it is possible to conclude that a certain conception of legal causality is present in EU non-contractual liability law.
109.
In particular, starting early on, the case-law expressed limits to the ‘but for’ test by excluding liability of EU institutions or bodies for damage that is too remote.
110.
In that case-law, it was sometimes found that the damage was too remote because of the contribution of others, including the injured party itself, to the damage. In Trubowest, for example, the Court of Justice thus considered that ‘even in the case of a possible contribution by the institutions to the damage for which compensation is sought, that contribution might be too remote because of some responsibility resting on others, possibly the appellants’. (
50
)
111.
The cases that take into consideration the contribution of the injured party were, to my mind, developed casuistically (
51
) and not as a result of a comprehensive theory regarding the legal assessment of the causal link. (
52
)
112.
The contribution of the injured party to the damage caused by an EU institution or body has been treated by the EU Courts in two different ways. In some cases, the injured party’s contribution was taken into consideration as an element leading to the lowering of the amount of damages for which the EU institution or body was liable, but which was not considered to break the causal link. (
53
) In a number of other cases, the contribution of the injured party has been regarded as an element that broke the causal link. In such cases, the EU Courts have reasoned that the injured party’s conduct, and not the institution’s conduct, was the determining cause of the damage. (
54
)
113.
The appellants claim that the General Court erred in law because the case-law takes into account the contribution of the injured party for the purpose of limiting the damage, and not as a factor breaking the causal link. That argument cannot be accepted, given that both lines of case-law exist, as demonstrated above.
114.
Nevertheless, I suggest that the existing cases in which the Court of Justice has found that there has been a break in the causal link due to the injured party’s own choices have mostly related to damage suffered in the course of business and cannot therefore be automatically transposed to the present case. These were predominantly cases relating to the market, such as dumping cases, (
55
) competition cases, (
56
) or merger cases, (
57
) in which the injured parties were economic operators and the Court reached the conclusion that the negligence or simply wrong business assessment of those parties brought about the rupture of the causal link.
115.
The alleged damage in the present case has nothing to do with the usual business risk that actors on the market have to account for. Likewise, it cannot be claimed that such damage occurred due to the negligence of the appellants, let alone that their negligence was the determining cause of the damage, which was one of the reasons for the Court to deny the existence of a causal link in Trubowest. (
58
)
116.
Rather, in the present case, the damage is the result of an alleged breach of fundamental rights, including the principle of non-refoulement, of the appellants who were at the same time in a vulnerable position. (
59
) Taking into consideration that the appellants were Syrian Kurds returned to Türkiye, it does not seem to me to be objectively possible to characterise their decision to flee to Iraq, as a country they considered to be safe, as a wholly autonomous decision on their part. Even if it was indeed their own decision, and the alternative to stay in Türkiye was not foreclosed, such a decision was hardly their ‘free choice’.
117.
In the light of the above, I propose to the Court to find that the factual causal link in the present case was not broken by the appellants’ own choice. Had there not been the allegedly unlawful omission by Frontex, the appellants would not have been faced with the need to make such a difficult life-choice decision.
118.
Therefore, I consider that the first part of the third ground of the appeal is well founded.
119.
That being said, I do not exclude the possibility to consider some heads of damage claimed by the appellants as too remote from Frontex’s omission and thus to exclude Frontex’s liability for them. That principally concerns the material damage relating to the costs incurred in settling in Iraq, which are costs that the appellants could not have avoided no matter where they would have settled. As part of the assessment of legal causality, there might be reasons to exclude this type of damage. However, that is a different type of reasoning from that made by the General Court, which was legally flawed and according to which the appellants’ own decision broke the link between Frontex’s omission and the damage suffered by the appellants. Only that reasoning was at issue in this appeal.
2. The causal link as regards the material damage related to the legal aid costs incurred in the complaints mechanism
120.
The appellants further claim that the General Court erred in law, in paragraph 70 of the judgment under appeal, in failing to find that legal representation was necessary for the submission of their complaints to Frontex in the present case due to particular circumstances relating to the unlawful handling of their complaints by Frontex and their lack of knowledge of EU languages.
121.
I am of the opinion that the General Court has not erred in its legal reasoning relating to this head of damage.
122.
In Internationaler Hilfsfonds v Commission, (
60
) the Court of Justice held that there was no direct causal link between the damage comprising legal costs incurred in complaint proceedings before the European Ombudsman and the actions of the Commission, since persons are free to choose to have recourse to the European Ombudsman and thus the costs incurred by them cannot be regarded as damage caused by the institution in question.
123.
In the present case, there seems to me to be no reason why a similar finding could not be made in respect of the appellants’ complaints in the context of the complaints mechanism as set out in Regulation 2016/1624. (
61
)
124.
Similar to the procedures before the Ombudsman, the complaints mechanism is an administrative mechanism, which is not mandatory under EU law, nor does it preclude other judicial and administrative remedies. (
62
)
125.
As regards the appellants’ allegations of inadequate handling of their complaints by Frontex, that does not call into question the nature of the complaints mechanism itself.
126.
The appellants’ arguments based on their lack of knowledge of EU languages are equally unconvincing. According to the second subparagraph of Article 72(10) of Regulation 2016/1624, the standardised complaint form is to be made available on Frontex’s website and in hardcopy during all of Frontex’s activities, ‘in languages that third-country nationals understand or are reasonably believed to understand’. This indicates that the EU legislature took that into account, but without drawing any conclusions from it as to the need for legal assistance.
127.
Therefore, I consider that the second part of the third ground of appeal should be rejected as unfounded.
D.
The fourth ground of appeal
128.
By the fourth ground of appeal, the appellants complain that, in paragraphs 44 to 46, 50 and 51 of the judgment under appeal, the General Court erred in law by finding certain evidence, namely Annexes C.1, C.3 to C.6 and E.1, inadmissible. In their view, the General Court misinterpreted Article 85(2) of its Rules of Procedure, in so far as the time-bar rule in that provision does not apply to evidence in rebuttal or to the amplification of previous evidence, as is the case here.
129.
In that respect, the appellants submit that: (i) Annex C.1 (an expert opinion, dated 2022), Annexes C.4 and C.5 (two reports from the Parliamentary Assembly of the Council of Europe, dated 2016) and Annex C.6 (extracts from the 2016 Annual Report of the European Asylum Support Office) constitute rebuttal evidence because they substantiate previously made claims and respond to arguments raised in Frontex’s defence; (ii) Annex C.3 (an undated written statement of one of the appellants) constitutes an amplification of previous evidence; and (iii) Annex E.1 (the operational plan that Frontex sent to the appellants in 2017) does not prejudice Frontex’s rights of defence because its contents were known to it.
130.
Frontex argues that the fourth ground of appeal is ineffective and, in any event, unfounded. First, that ground has no bearing on the success of the case if the annexes are included in the case file or not. Second, to allow any evidence provided at a late stage to be admitted as rebuttal evidence would mean that the time-bar rule in Article 85(1) and (2) of the Rules of Procedure of the General Court would never apply, and, as the General Court correctly held, the appellants did not justify why the evidence was submitted late.
131.
In my view, contrary to Frontex’s assertion, the fourth ground of appeal is not ineffective. (
63
)
132.
Under the case-law, the prevailing principle in EU law is that of the unfettered production of evidence, meaning that the parties have, in principle, the right to rely on any form of evidence in order to prove a particular fact. (
64
) Consequently, even documents which are not decisive for the outcome of the action, but only, for example, aim to clarify the debate or to supplement the information provided to the EU Courts, are acceptable. The right of a party to produce evidence is not linked to its objective necessity for the debate.
133.
Nonetheless, I agree with Frontex that this ground of appeal is unfounded.
134.
As the General Court observed in paragraph 44 of the judgment under appeal, the parties must state the reasons for the delay in submitting or offering new evidence, and the EU Courts have jurisdiction to review the merits of those reasons and, if its belated production is not justified to the requisite legal standard or substantiated, to reject it. In that respect, according to case-law, the belated submission of evidence may be justified, in particular, by the fact that the party did not previously have the evidence in question at its disposal or if the belated production of evidence by the opposing party justifies the file being supplemented in observance of the inter partes principle. (
65
)
135.
In the present case, as regards the documents submitted at the late stage of the reply (Annexes C.1 and C.3 to C.6), it is apparent that those documents did not relate to new aspects introduced into the proceedings by Frontex’s defence. Moreover, as regards the document submitted before the close of the oral part of the procedure (Annex E.1), it is clear that the appellants’ own error is not a valid justification for delay, and the fact that its submission was not likely to undermine Frontex’s rights of defence is irrelevant.
136.
In those circumstances, the General Court was fully entitled to find that the appellants had not justified the late submission of the evidence in question to the requisite legal standard and, consequently, to reject that evidence as inadmissible.
137.
Therefore, I consider that the fourth ground of appeal should be rejected as unfounded.
VI. Consequences
138.
On the basis of the foregoing analysis, I propose that the judgment under appeal be set aside as regards the first and second grounds of appeal and the first part of the third ground of appeal, and that the appeal be dismissed as regards the second part of the third ground of appeal and the fourth ground of appeal.
139.
Under Article 61 of the Statute of the Court of Justice of the European Union, the Court of Justice may, where it sets aside a decision of the General Court, itself give final judgment in the matter, where the state of proceedings so permits.
140.
That is not the case here. Even though I consider that the General Court’s reasoning that the causal link could not be established in the present case is legally flawed, in order to find out whether such a causal link exists, it would be necessary to establish whether there was a return decision. That entails an assessment of the facts, which has not yet been carried out by the General Court. Therefore, the Court of Justice cannot rule on the existence of a causal link, nor on the other conditions for incurring liability.
VII. Conclusion
141.
I propose that the Court of Justice should:
–
set aside the judgment of the General Court of 6 September 2023, WS and Others v Frontex (T‑600/21, EU:T:2023:492);
–
refer the case back to the General Court.
(
1
)	Original language: English.
(
2
)	Frontex is a common name for the EU agency set up in 2004 by Council Regulation (EC) No 2007/2004 of 26 October 2004 (OJ 2004 L 349, p.1) under the name ‘European Agency for the Management of Operational Cooperation at the External Borders of the Member States of the European Union’ to assist Member States in the management of the external EU borders. The official title of that agency was changed to ‘European Border and Coast Guard Agency’ by Regulation (EU) 2016/1624 of the European Parliament and of the Council of 14 September 2016 on the European Border and Coast Guard and amending Regulation (EU) 2016/399 of the European Parliament and of the Council and repealing Regulation (EC) No 863/2007 of the European Parliament and of the Council, Council Regulation (EC) No 2007/2004 and Council Decision 2005/267/EC (OJ 2016 L 251, p. 1), which is applicable in the present case. That regulation was replaced by Regulation (EU) 2019/1896 of the European Parliament and of the Council of 13 November 2019 on the European Border and Coast Guard and repealing Regulations (EU) No 1052/2013 and (EU) 2016/1624 (OJ 2019 L 295, p. 1).
(
3
)	Judgment of 6 September 2023, WS and Others v Frontex (T‑600/21, ‘the judgment under appeal’, EU:T:2023:492).
(
4
)	See, for example, judgment of 5 March 2024, Kočner v Europol (C‑755/21 P, EU:C:2024:202, paragraphs 117 and 118). It should be pointed out that, as the Court has consistently held, the EU Courts are not required to examine those conditions in any particular order. See, for example, judgments of 18 March 2010, Trubowest Handel and Makarov v Council and Commission (C‑419/08 P, ‘Trubowest’, EU:C:2010:147, paragraphs 40 to 50), and of 5 September 2019, European Union v Guardian Europe and Guardian Europe v European Union (C‑447/17 P and C‑479/17 P, EU:C:2019:672, paragraph 148).
(
5
)	The Court is hearing this case in parallel with another case, Hamoudi v Frontex (C‑136/24 P), which raises important, albeit different, questions regarding the assessment of the condition relating to damage in an action for damages brought against Frontex in the context of its maritime operational activities. See Opinion of Advocate General Norkus in Hamoudi v Frontex (C‑136/24 P, EU:C:2025:257).
(
6
)	According to a news article annexed to their application before the General Court (Amnesty International, ‘Greece: Evidence points to illegal forced return of Syrian refugees to Turkey’, 28 October 2016), they were apparently rescued in Greek waters when their boat travelling from Türkiye to Italy encountered problems and they were taken to the island of Milos.
(
7
)	The documents attesting to such declarations are annexed to the application.
(
8
)	That return operation was part of a joint operation coordinated by Frontex known as Joint Operation Poseidon, with several participating Member States. It was launched to help Greece manage irregular migration flows along its borders. As is apparent from the case file, Frontex and Greece were carrying out the joint return operation in the context of the EU-Turkey Statement (European Council, 18 March 2016). According to point 1 of that statement: ‘All new irregular migrants crossing from Turkey into Greek islands as from 20 March 2016 will be returned to Turkey. This will take place in full accordance with EU and international law, thus excluding any kind of collective expulsion. All migrants will be protected in accordance with the relevant international standards and in respect of the principle of non-refoulement …’.
(
9
)	In that respect, that report indicated that, in June 2017, Frontex had changed the template used by Greece to communicate to it the list of third-country nationals to be readmitted to Türkiye. Furthermore, in October 2017, Frontex had agreed to include additional information in the web-based Frontex Application for Return (‘FAR’), so that Member States were able to declare and confirm the existence of enforceable return decisions as a new procedural safeguard in return operations.
(
10
)	See ECtHR, decision of 19 January 2023, L.H.M. and Others v. Greece (CE:ECHR:2023:0119DEC003052017).
(
11
)	Article 60(3) of Regulation 2016/1624 states: ‘In the case of non-contractual liability, [Frontex] shall, in accordance with the general principles common to the laws of the Member States, make good any damage caused by its departments or by its staff in the performance of their duties.’
(
12
)	‘Frontex Standard Operating Procedure to ensure respect of Fundamental Rights (FR) in Frontex joint operations and pilot projects’, dated 16 July 2012 (‘the Standard Operating Procedure’), annexed to the application.
(
13
)	‘Frontex Code of Conduct for joint return operations coordinated by Frontex’, dated 7 October 2013 (‘the Code of Conduct’), annexed to the application.
(
14
)	As indicated in paragraphs 58 and 59 of the judgment under appeal, the material damage alleged by the applicants consisted of: (i) the cost of renting a house and purchasing furniture in Saruj (Türkiye); (ii) the expenses of fleeing to Iraq; (iii) the rent paid in Iraq; (iv) the electricity costs for their home in Iraq; (v) the children’s school fees in Iraq; (vi) the subsistence costs in Iraq; and (vii) the cost of legal aid for assistance with their complaints against Frontex. The non-material damage alleged by the applicants consisted of: (i) the feelings of anguish, particularly on the part of the children, caused by the return flight to Türkiye on account of their separation during that flight, being prohibited from speaking and the presence of uniformed escort officers and police officers; and (ii) the feelings of fear and suffering linked to the extremely difficult and dangerous journey to Iraq because of the fear of being returned to Syria by the Turkish authorities.
(
15
)	Directive of the European Parliament and of the Council of 16 December 2008 on common standards and procedures in Member States for returning illegally staying third-country nationals (OJ 2008 L 348, p. 98). The European Commission recently submitted a proposal to replace that directive: see COM(2025) 1010 final of 11 March 2025.
(
16
)	Directive of the European Parliament and of the Council of 26 June 2013 on common procedures for granting and withdrawing international protection (OJ 2013 L 180, p. 60). That directive has been replaced by Regulation (EU) 2024/1348 of the European Parliament and of the Council of 14 May 2024 establishing a common procedure for international protection in the Union and repealing Directive 2013/32 (OJ L 2024/1348).
(
17
)	Under settled case-law, while the findings and the assessment of the facts in an action for EU non-contractual liability are for the General Court, the Court of Justice can review the legal characterisation of the facts and the legal conclusions drawn from them in determining whether there is a causal link between the unlawful conduct and the damage alleged. See, for example, judgments of 16 July 2009, Commission v Schneider Electric (C‑440/07 P, EU:C:2009:459, paragraphs 192 and 193), and of 7 June 2018, Equipolymers and Others v Council (C‑363/17 P, EU:C:2018:402, paragraph 22).
(
18
)	I refer, in that regard, to the application (points 4 to 13 and 137 and 138), the defence (points 5 to 8 and 39) and the reply (points 12 to 18 and 64 to 66).
(
19
)	Indeed, such arguments were framed by the appellants under the heading of ‘shared responsibility’.
(
20
)	See, for example, Fink, M., Rauchegger, C. and De Coninck, J., ‘The Action for Damages as a Fundamental Rights Remedy’, in Fink, M. (ed.), Redressing Fundamental Rights Violations by the EU: The Promise of the ‘Complete System of Remedies’, Cambridge University Press, Cambridge, 2024, pp. 36 to 63, in particular p. 56.
(
21
)	See, in that respect, Wakefield, J., Judicial Protection Through the Use of Article 288(2) EC, Kluwer Law International, The Hague, 2002, p. 222, indicating that: ‘It is not possible to give an answer to the question, “Did the [EU] Institutions cause the damage?”, without knowing what it was that the [EU] Institutions ought to have been doing.’
(
22
)	This was the reaction of many scholars to the judgment under appeal. See, for example, Laconi, A., ‘Responsibility for fundamental rights breaches in return operations: shades and lights on the first action for damages against Frontex’, DPCE Online, Vol. 61(4), 2023, pp. 3689 to 3697; Cornelisse, G., ‘EU Boots on the Ground and Effective Judicial Protection against Frontex’s Operational Powers in Return: Lessons from Case T‑600/21’, European Journal of Migration and Law, Vol. 26, 2024, pp. 356 to 380; Gkliati, M., ‘Shaping the Joint Liability Landscape? The Broader Consequences of WS v
Frontex for EU Law’, European Papers, Vol. 9, 2024, pp. 69 to 86; Nicolosi, S.F., ‘The European Border and Coast Guard Agency (Frontex) and the limits to effective judicial protection in European Union law’, European Law Journal, Vol. 30, 2024, pp. 149 to 164; Rizzuto Ferruzza, S., Frontex and Effective Remedies: Assessing mechanisms of legal protection in a shared enforcement space, doctoral thesis, University of Luxembourg, 2025, in particular pp. 197 to 207. As regards blogposts, see, for example, Davies, G., ‘The General Court finds Frontex not liable for helping with illegal pushbacks: it was just following orders’, European Law Blog, 11 September 2023; De Coninck, J., ‘Shielding Frontex: On the EU General Court’s “WS and others v Frontex”’, Verfassungsblog, 9 September 2023; Tas, S., ‘Op-Ed: Frontex above the law – a missed opportunity for a landmark judgment on Frontex’s responsibility with regards fundamental rights violations: WS and Others v Frontex (T‑600/21)’, EU Law Live, 20 September 2023; Ziebritzki, C., ‘A Hidden Success: Why the EU General Court’s Frontex Judgment is Better than it Seems’, Verfassungsgblog, 13 October 2023.
(
23
)	See Article 51(2) of the Charter. See also, for example, judgment of 22 November 2022, Staatssecretaris van Justitie en Veiligheid (Removal – Medicinal cannabis) (C‑69/21, EU:C:2022:913, paragraph 87).
(
24
)	See also recital 34 of Regulation 2016/1624.
(
25
)	Under settled case-law, a Member State may not remove an illegally staying third-country national unless a return decision has first been adopted in compliance with the substantive and procedural safeguards established by that directive. See, for example, judgments of 17 December 2020, Commission v Hungary (Reception of applicants for international protection) (C‑808/18, EU:C:2020:1029, paragraph 253), and of 22 November 2022, Staatssecretaris van Justitie en Veiligheid(Removal – Medicinal cannabis) (C‑69/21, EU:C:2022:913, paragraph 54).
(
26
)	See, in that regard, in particular Articles 5 and 9 and recital 8 of Directive 2008/115. The Court of Justice has held that Article 5 of Directive 2008/115 obliges Member States to observe, at all stages of the return procedure, the principle of non-refoulement. See, for example, judgment of 22 November 2022, Staatssecretaris van Justitie en Veiligheid (Removal – Medicinal cannabis) (C‑69/21, EU:C:2022:913, paragraphs 55).
(
27
)	Emphasis added.
(
28
)	It should be noted that, in Regulation 2019/1896, which replaced Regulation 2016/1624, alongside provisions precluding Frontex from entering into the merits of return decisions (see Article 10(1)(n), Article 48(1) and Article 50(1) of that regulation), there is also a requirement in Article 50(2) thereof, which provides: ‘The Member State concerned shall confirm to [Frontex] that all returnees covered by a return operation organised or coordinated by [Frontex] are the subject of an enforceable return decision.’ This suggests that Frontex’s obligation to verify that persons covered by joint return operations are subject to a return decision does not represent a situation of Frontex entering into the merits of such a decision.
(
29
)	See, for example, Wils, W., ‘Concurrent Liability of the Community and a Member State’, European Law Review, Vol 17(3), 1992, pp. 191 to 206; Oliver, P., ‘Joint Liability of the Community and the Member States’, in Heukels, T. and McDonnell, A. (eds), The Action for Damages in Community
Law, Kluwer Law International, The Hague, 1997, pp. 285 to 309; de Visser, M., ‘The Concept of Concurrent Liability and Its Relationship with the Principle of Effectiveness: A One-Way Ticket into Oblivion’, Maastrict Journal of European
and Comparative Law, Vol. 11(1), 2004, pp. 47 to 70; Biondi, A. and Farley, M., The Right to Damages in European Law, Wolters Kluwer, Alphen aan den Rijn, 2009, pp. 163 to 199; Brüggemeier, G., Tort Law in the European Union, 2nd edition, Wolters Kluwer, Alphen aan den Rijn, 2018, pp. 155 and 156.
(
30
)	See, for example, Fink, M., Frontex and Human Rights: Responsibility in ‘Multi-Actor Situations’ under the ECHR and EU Public Liability Law, Oxford University Press, Oxford, 2018, in particular pp. 265 to 306; Fink, M., ‘EU Liability for Contributions To Member States’ Breaches of EU Law’, Common Market Law Review, Vol. 56(5), 2019, pp. 1227 to 1264, in particular pp. 1259 to 1262; De Coninck, J., The EU’s Human Rights Responsibility Gap: Deconstructing Human Rights Impunity of International Organisations, Hart, Oxford, 2024, in particular pp. 115 to 141 and 262 and 263.
(
31
)	See, in that regard, Opinion of Advocate General Rantos in Kočner v Europol (C‑755/21 P, EU:C:2023:481, in particular points 35 and 50 to 52).
(
32
)	See Article 3(1) and recital 5 of Regulation 2016/1624.
(
33
)	See also recital 6 of Regulation 2016/1624.
(
34
)	See judgment of 14 July 1967 (5/66, 7/66, 13/66 to 16/66 and 18/66 to 24/66, EU:C:1967:31; ECR 1967 p. 245, in particular p. 262).
(
35
)	See judgment of 5 March 2024 (C‑755/21 P, EU:C:2024:202).
(
36
)	Regulation of the European Parliament and of the Council of 11 May 2016 on the European Union Agency for Law Enforcement Cooperation (Europol) and replacing and repealing Council Decisions 2009/371/JHA, 2009/934/JHA, 2009/935/JHA, 2009/936/JHA and 2009/968/JHA (OJ 2016 L 135, p. 53).
(
37
)	See judgment of 5 March 2024, Kočner v Europol (C‑755/21 P, EU:C:2024:202, paragraph 68).
(
38
)	For an extensive analysis of the implications of the judgment in Kočner v Europol, see De Coninck, J. and Tas, S., ‘Investigating five dimensions of the EU’s liability regime: Marián Kočner’, Common Market Law Review, Vol. 62(1), 2025, pp. 195 to 214.
(
39
)	See, in that regard, for example, Davies, cited in footnote 22 to this Opinion.
(
40
)	See footnote 14 to this Opinion summarising all the heads of damage claimed by the appellants.
(
41
)	See, for example, Biondi and Farley, cited in footnote 29 to this Opinion, pp. 146 to 154; van Dam, C., European Tort Law, 2nd edition, Oxford University Press, Oxford, 2013, Chapter 11, pp. 307 to 345.
(
42
)	See, in that respect, van Dam, cited in footnote 41 to this Opinion, p. 311.
(
43
)	As eloquently expressed by one author, ‘these are the mythical formulae applied by the national priests of tort law to avert the dangers of consequences going too far for the tortfeasor. Behind the masks of these tests, policy reasons play a significant role.’ van Dam, cited in footnote 41 to this Opinion, p. 311.
(
44
)	See, for example, judgments of 4 October 1979, Dumortier and Others v Council (64/76, 113/76, 167/78, 239/78, 27/79, 28/79 and 45/79, EU:C:1979:223, paragraph 21); Trubowest (paragraph 53); of 5 September 2019, European Union v Guardian Europe and Guardian Europe v European Union (C‑447/17 P and C‑479/17 P, EU:C:2019:672, paragraphs 32 and 135); and of 5 March 2024, Kočner v Europol (C‑755/21 P, EU:C:2024:202, paragraph 135).
(
45
)	In the judgment under appeal, the General Court referred to the judgment of 30 November 2011, Transnational Company Kazchrome and ENRC Marketing v Council and Commission (T‑107/08, EU:T:2011:704, paragraph 80) (emphasis added). The General Court has often reiterated that statement. See, for example, judgments of 7 December 2017, Missir Mamachi di Lusignano and Others v Commission (T‑401/11 P RENV‑RX, EU:T:2017:874, paragraph 69), and of 23 May 2019, Remag Metallhandel and Jaschinsky v Commission (T‑631/16, EU:T:2019:352, paragraph 52).
(
46
)	But see Opinion of Advocate General Mengozzi in Holcim (Deutschland) v Commission (C‑282/05 P, EU:C:2007:19, points 91 and 92).
(
47
)	See, for example, judgments of 4 October 1979, Dumortier and Others v Council (64/76, 113/76, 167/78, 239/78, 27/79, 28/79 and 45/79, EU:C:1979:223, paragraph 21), and Trubowest (paragraph 53) (emphasis added).
(
48
)	See, in that regard, Opinion of Advocate General Trabucchi in Compagnie Continentale France v Council (169/73, EU:C:1974:135, point 1).
(
49
)	See, for example, Gutman, K., ‘The Evolution of the Action for Damages Against the European Union and Its Place in the System of Judicial Protection’, Common Market Law Review, Vol. 48(3), 2011, pp. 695 to 750, in particular pp. 724 and 725; van Dam, cited in footnote 41 to this Opinion, pp. 321 to 324; Strand, M. and García-Perrote Martínez, I., The Passing-On Problem in Damages and Restitution under EU Law, 2nd edition, Edward Elgar, Cheltenham, 2023, in particular pp. 78 to 89.
(
50
)	Trubowest (paragraph 59). See also order of 31 March 2011, Mauerhofer v Commission (C‑433/10 P, EU:C:2011:204, paragraph 132).
(
51
)	Thus, for example, in his Opinion in Commission v Schneider Electric (C‑440/07 P, EU:C:2009:48, point 164), Advocate General Ruiz-Jarabo Colomer noted: ‘The parameters for this analysis are provided by the case-law of the Court of Justice, which states that, where the non-contractual liability of [EU] institutions is concerned, a lack of foresight or prudence on the part of the applicant for compensation can affect the causal link between the unlawful act and the damage, and may reduce … the liability or even extinguish it. … Nevertheless, apart from these general observations, proceedings in this area inevitably reveal a case-by-case approach.’
(
52
)	But see judgment of 7 December 2017, Missir Mamachi di Lusignano and Others v Commission (T‑401/11 P RENV‑RX, EU:T:2017:874). In that case, the General Court offered two theories, a theory of equivalence of conditions and a theory of adequate causation, finding that more cases fit within the latter theory, which, however, did not exclude reliance on the former theory.
(
53
)	For example, in Fresh Marine v Commission, the General Court held that the Commission was liable for only half of the damage until a certain point of time, as the choices of the applicant were considered to have equally contributed to the damage sustained: see judgment of 24 October 2000 (T‑178/98, EU:T:2000:240, paragraphs 135 and 136) (appeal dismissed in judgment of 10 July 2003, Commission v Fresh Marine, C‑472/00 P, EU:C:2003:399). See also judgment of 27 March 1990, Grifoni v Commission (C‑308/87, EU:C:1990:134, paragraphs 16 to 18), in which the Court of Justice did not consider that the applicant’s own contribution broke the causal link, but rather influenced the amount of damages for which the Commission was liable. In the judgment of 7 November 1985, Adams v Commission (145/83, EU:C:1985:448, paragraphs 53 to 55), the Court of Justice considered that, even if the applicant contributed significantly to the damage, that resulted in the diminished extent of the Commission’s liability, but did not break the causal link.
(
54
)	See, for example, judgments of 16 July 2009, Commission v Schneider Electric (C‑440/07 P, EU:C:2009:459, paragraph 205); of 28 February 2013, Inalca and Cremonini v Commission (C‑460/09 P, EU:C:2013:111, paragraph 118); and of 5 September 2019, European Union v Guardian Europe and Guardian Europe v European Union (C‑447/17 P and C‑479/17 P, EU:C:2019:672, paragraph 41).
(
55
)	See, for example, Trubowest (paragraphs 53 to 65).
(
56
)	See, for example, judgment of 5 September 2019, European Union v Guardian Europe and Guardian Europe v European Union (C‑447/17 P and C‑479/17 P, EU:C:2019:672, paragraphs 32 to 42), in which the damages claim concerned bank guarantee costs caused by the excessive length of the procedure relating to the legality of a fine based on Article 101 TFEU. See also, but in relation to security costs for a contested fine imposed for irregularities found in the refunds for exported beef and veal, judgment of 28 February 2013, Inalca and Cremonini v Commission (C‑460/09 P, EU:C:2013:111, paragraphs 117 to 124).
(
57
)	See, for example, judgment of 16 July 2009, Commission v Schneider Electric (C‑440/07 P, EU:C:2009:459, paragraphs 197 to 207).
(
58
)	See Trubowest (paragraph 61).
(
59
)	In that respect, the ECtHR considered in the judgment of 21 January 2011, M.S.S. v. Belgium and Greece (CE:ECHR:2011:0121JUD003069609, § 232), that ‘the Court must take into account that the applicant, being an asylum seeker, was particularly vulnerable because of everything he had been through during his migration and the traumatic experiences he was likely to have endured previously’.
(
60
)	See judgment of 28 June 2007 (C‑331/05 P, EU:C:2007:390, in particular paragraphs 24 to 29). See also Opinion of Advocate General Trstenjak in Internationaler Hilfsfonds v Commission (C‑331/05 P, EU:C:2007:191, points 91 to 96).
(
61
)	See Article 72 of Regulation 2016/1624.
(
62
)	See, in that regard, recital 50 of Regulation 2016/1624.
(
63
)	According to the case-law, in the context of an appeal, where one of the grounds adopted by the General Court is sufficient to sustain the operative part of its judgment, any defects that might vitiate other grounds of the judgment concerned cannot influence that operative part and, accordingly, a plea relying on such defects is ineffective and must be dismissed. See, for example, judgments of 14 October 2014, Buono and Others v Commission (C‑12/13 P and C‑13/13 P, EU:C:2014:2284, paragraph 47), and of 21 December 2023, United Parcel Service v Commission (C‑297/22 P, EU:C:2023:1027, paragraph 64).
(
64
)	See, for example, judgment of 12 December 2024, DD v FRA (C‑130/22 P, EU:C:2024:1018, paragraph 92). See also Opinion of Advocate General Wahl in Ombudsman v Staelen (C‑337/15 P, EU:C:2016:823, point 84).
(
65
)	See, for example, judgments of 16 September 2020, BP v FRA (C‑669/19 P, EU:C:2020:713, paragraph 41), and of 23 November 2023, Ryanair andAirport Marketing Services v Commission (C‑758/21 P, EU:C:2023:917, paragraph 43).