DEMİRHAN A OSTATNÍ proti Turecku

SECOND SECTION

CASE OF DEMİRHAN AND OTHERS v. TÜRKİYE

(Applications nos. 1595/20 and 238 others –

see appended list)

JUDGMENT

STRASBOURG

22 July 2025

This judgment will become final in the circumstances set out in Article 44 § 2 of the Convention. It may be subject to editorial revision.

In the case of Demirhan and Others v. Türkiye,

The European Court of Human Rights (Second Section), sitting as a Chamber composed of:

Arnfinn Bårdsen, President,
Saadet Yüksel,
Tim Eicke,
Jovan Ilievski,
Oddný Mjöll Arnardóttir,
Gediminas Sagatys,
Stéphane Pisani, judges,
and Hasan Bakırcı, Section Registrar,

Having regard to:

the applications (nos. 1595/20 and 238 others) against the Republic of Türkiye lodged with the Court under Article 34 of the Convention for the Protection of Human Rights and Fundamental Freedoms (“the Convention”) by 239 Turkish nationals (“the applicants”), on the various dates indicated in the appended table;

the decision to give notice to the Turkish Government (“the Government”) of the complaints under Article 6 § 1 (the right to a fair trial) and Article 7 of the Convention (no punishment without law);

the parties’ observations;

Having deliberated in private on 1 July 2025,

Delivers the following judgment, which was adopted on that date:

INTRODUCTION

1. The case concerns the applicants’ convictions for membership of an armed terrorist organisation described by the Turkish authorities as the “Fetullahist Terror Organisation/Parallel State Structure” (Fetullahçı Terör Örgütü / Paralel Devlet Yapılanması, hereinafter referred to as “the FETÖ/PDY”), considered by the authorities to be behind the coup attempt that took place in Türkiye on 15 July 2016. The convictions were based decisively on the applicants’ use of an encrypted messaging application by the name of “ByLock”, which the domestic courts held was designed for the exclusive use of the members of the FETÖ/PDY.

THE FACTS

2. A list of the applicants is set out in the appendix. Some of the applicants were represented by lawyers, whose names are also listed therein.

3. The Government were represented by their Agent, Mr Abdullah Aydın, Head of the Department of Human Rights of the Ministry of Justice of the Republic of Türkiye.

4. The facts of the case, as submitted by the parties, may be summarised as follows.

1. BACKGROUND TO THE CASE

5. On the night of 15 to 16 July 2016 a group of members of the Turkish armed forces calling themselves the “Peace at Home Council” attempted to carry out a military coup aimed at overthrowing the democratically elected Parliament, Government and President of Türkiye.

6. During the attempted coup, more than 8,000 military personnel under the instigators’ control bombarded several strategic State buildings, including the Parliament building and the presidential compound, attacked the hotel where the President was staying and the convoy in which the Prime Minister was travelling, held the Chief of General Staff as well as a number of high ranking generals hostage, attacked and occupied a number of public institutions, occupied television studios, blocked the bridges over the Bosphorus and the airports in Istanbul with tanks and armoured vehicles, and fired on demonstrators who had taken to the streets to oppose the coup attempt. According to the figures provided by the Government, 253 people, including civilians, were killed on the night in question and 2,740 people were injured. The Government also indicated that in the course of the coup attempt, some 70 military aircraft, including F-16 fighter jets and helicopters, 3 ships, 246 armoured vehicles, including 74 tanks, and approximately 4,000 light arms were used.

7. The day after the attempted military coup, the national authorities blamed the network linked to Fetullah Gülen, a Turkish citizen who lived in Pennsylvania (United States of America) at the time and considered to be the leader of the FETÖ/PDY. The authorities attributed responsibility for the coup attempt to members of the FETÖ/PDY who had infiltrated the Turkish armed forces.

8. On 16 July 2016 the Bureau for Crimes against the Constitutional Order at the Ankara Chief Public Prosecutor’s Office initiated a criminal investigation into the attempted coup. Acting within the framework of that investigation, the regional prosecutors’ offices launched criminal investigations against individuals suspected of being involved in the coup attempt, as well as against those suspected of having links to the FETÖ/PDY.

9. On 20 July 2016 the Government declared a state of emergency for a period of ninety days as from 21 July 2016, which was subsequently prolonged on seven occasions, each time for further ninety-day periods.

10. On 21 July 2016 the Turkish authorities gave notice to the Secretary General of the Council of Europe of a derogation from the Convention under Article 15 (see paragraph 22 below; see Yüksel Yalçınkaya v. Türkiye [GC], no. 15669/20, § 205, 26 September 2023).

11. On 18 July 2018 the state of emergency was lifted.

12. The broader domestic background and context to the present applications was set out by the Court in Yüksel Yalçınkaya (cited above, §§ 10-22 and 108-40).

2. APPLICANTS’ CONVICTIONS

13. As indicated in paragraph 8 above, the prosecutors’ offices across the country launched widespread investigations following the coup attempt against persons suspected of having links to the FETÖ/PDY. In that connection, criminal investigations were initiated against the present applicants in view of their suspected membership of the FETÖ/PDY and they were subsequently charged with membership of an armed terrorist organisation under Article 314 § 2 of the Turkish Criminal Code.

14. On various dates, the applicants were convicted for membership of the FETÖ/PDY, and those convictions were upheld by the regional courts of appeal and the Court of Cassation. The convictions were based decisively on the applicants’ alleged use of an encrypted messaging application by the name of “ByLock”, which the domestic courts held was designed for the exclusive use of the members of the FETÖ/PDY (see Yüksel Yalçınkaya, cited above, §§ 155-65, for the Court of Cassation’s “landmark judgments” in that regard). The position taken by the domestic courts and authorities was that the establishment of the use of ByLock was sufficient on its own for conviction under Article 314 § 2 of the Criminal Code (ibid., § 257).

15. The applicants’ use of ByLock was established on the basis of examinations conducted by the investigating authorities on the ByLock data obtained by the National Intelligence Agency of Türkiye (Milli İstihbarat Teşkilatı, hereinafter referred to as “the MİT”) from the messaging application’s main server located in Lithuania. Those data enabled the authorities to extract information on the applicants’ ByLock user-IDs, the telephone (or the IP) numbers and IMEI numbers of the devices on which the application was used, the first date of connection to the application’s server and the total number of connections identified (ibid., §§ 34, 55, 78 and 80). That information was verified against the internet traffic data (also known as the CGNAT data) – which were procured by the Information and Communications Technologies Authority (“the BTK”) and which showed connections made to the ByLock IPs from Türkiye (ibid., §§ 119, 120, 177 and 319) – and the HTS (Historical Traffic Search) records pertaining to the GSM lines used by the applicants (ibid., § 80).

16. Other evidence against the applicants, if any, involved an admission of using ByLock, decrypted message content confirming use of that application or witness statements attesting to such use; membership of a trade union, association and/or foundation considered to be affiliated with the FETÖ/PDY; employment by and/or membership of FETÖ/PDY‑affiliated institutions, organisations or companies, or witness statements as regards such employment; account activities at Bank Asya, which was considered by the authorities to be a part of the financial structure of the FETÖ/PDY; possession of pro-FETÖ/PDY publications or other audio-visual material; participation in trips considered to have been organised by the FETÖ/PDY and records of exit from and entry to Türkiye; donations to FETÖ/PDY-affiliated foundations; participation in various demonstrations considered to be in support of the FETÖ/PDY; social media posts in favour of the organisation; residence in FETÖ/PDY student houses or dormitories; use of other messaging applications, such as Kakao Talk or Eagle, to communicate with other members of the organisation; and HTS records indicating communications with others prosecuted of the same offence. In the case of some of the applicants, the convictions were ordered without waiting for the submission to the case files of the detailed ByLock findings and evaluation reports – which potentially included decrypted content of communications over ByLock – on the ground that the establishment of the use of that application sufficed for conviction, irrespective of the nature and content of the communications.

17. The individual applications lodged by the applicants with the Constitutional Court against their convictions were summarily dismissed by that court as being inadmissible, on the basis of its case-law endorsing the Court of Cassation’s landmark judgments on the matter (ibid., §§ 169-88).

3. COURT’S RULING IN YÜKSEL YALÇINKAYA v. TÜRKİYE

18. On 26 September 2023 the Court’s Grand Chamber adopted a judgment in Yüksel Yalçınkaya (cited above). The case concerned the conviction of the applicant, a former teacher, under Article 314 § 2 of the Criminal Code for membership of the FETÖ/PDY. The conviction was based decisively on the applicant’s use of the ByLock application. Other evidence against the applicant included his use of an account at Bank Asya and his membership of a trade union and an association that were considered to be affiliated with the FETÖ/PDY.

19. The Court essentially found in that judgment that the applicant’s conviction had been secured without duly establishing the presence of all constituent elements of the relevant offence set out under Article 314 § 2 of the Criminal Code (in particular the mental element) in an individualised manner, in contravention of the requirements under domestic law and the principles of legality and foreseeability that were at the core of the protection under Article 7 (ibid., § 267). It noted that although the use of ByLock was technically not part of the actus reus of the impugned offence, the domestic courts’ interpretation had in practice the effect of equating the mere use of ByLock with knowingly and willingly being a member of an armed terrorist organisation. The Court therefore held that this unforeseeable and expansive interpretation of the relevant domestic law by the domestic courts had violated Article 7 of the Convention (ibid., §§ 267‑72). It also found, inter alia, a breach of Article 6 § 1, mainly on account of the inability of the applicant to effectively challenge the key evidence against him (the ByLock data) in proceedings that complied with the guarantees of that provision and the domestic courts’ failure to support their decisions with adequate and relevant reasoning, particularly in relation to the characterisation of ByLock as an exclusively organisational communication tool (ibid., §§ 273-356).

20. In so far as individual measures of redress were concerned, the Court considered that the reopening of the criminal proceedings allowed under domestic law would be the most appropriate way of putting an end to the violations found (ibid., § 425). It further held, however, that the Turkish authorities also had to take general measures as appropriate to address the systemic problem which had led to the findings of a violation under Articles 7 and 6 § 1 of the Convention, notably the domestic courts’ approach to the use of ByLock. It noted in that connection that there were over 8,000 applications on the Court’s docket at the material time involving similar complaints raised under Articles 7 and/or 6 § 1 relating to convictions for membership of the FETÖ/PDY based on the use of ByLock (hereinafter referred to as the “follow-up applications”). The defects identified in the Yüksel Yalçınkaya judgment (cited above) therefore needed to be addressed by the Turkish authorities, to the extent relevant and possible, on a larger scale – that is, beyond the specific case of Mr Yalçınkaya (ibid., §§ 413-18).

RELEVANT LEGAL FRAMEWORK AND PRACTICE

1. RELEVANT DOMESTIC LAW AND PRACTICE

21. A description of the relevant law and practice has been set out in Yüksel Yalçınkaya (cited above, §§ 141-93).

2. NOTICE OF DEROGATION BY TÜRKİYE

22. On 21 July 2016 the Permanent Representative of Türkiye to the Council of Europe sent the Secretary General of the Council of Europe a notice of derogation (see, for the text of the notice of derogation, Yüksel Yalçınkaya, cited above, § 205).

23. The notice of derogation was withdrawn on 8 August 2018, following the end of the state of emergency.

THE LAW

1. JOINDER OF THE APPLICATIONS

24. Having regard to the similar subject matter of the applications, the Court finds it appropriate to examine them jointly in a single judgment.

2. PRELIMINARY QUESTION CONCERNING THE DEROGATION BY TÜrkİye

25. The Government emphasised at the outset that the applications should be examined with due regard to the derogation of which the Secretary General of the Council of Europe had been notified on 21 July 2016 under Article 15 of the Convention (see, for similar arguments, Yüksel Yalçınkaya, cited above, §§ 208 and 209). Article 15 provides:

“1. In time of war or other public emergency threatening the life of the nation any High Contracting Party may take measures derogating from its obligations under [the] Convention to the extent strictly required by the exigencies of the situation, provided that such measures are not inconsistent with its other obligations under international law.

2. No derogation from Article 2, except in respect of deaths resulting from lawful acts of war, or from Articles 3, 4 (paragraph 1) and 7 shall be made under this provision.

3. Any High Contracting Party availing itself of this right of derogation shall keep the Secretary General of the Council of Europe fully informed of the measures which it has taken and the reasons therefor. It shall also inform the Secretary General of the Council of Europe when such measures have ceased to operate and the provisions of the Convention are again being fully executed.”

26. The Court notes the finding made in many cases relating to the attempted military coup that this attempt had amounted to a “public emergency threatening the life of the nation” within the meaning of the Convention and that the formalities required by Article 15 § 3 had been respected by the Turkish authorities (see, for instance, Yüksel Yalçınkaya, cited above, § 212, and the cases cited therein). It sees no reason to depart from that finding in the present case. As to whether the specific actions taken against the applicants were strictly required by the exigencies of the situation and consistent with the respondent State’s other obligations under international law, these points will be considered as part of the examination of the relevant complaints on the merits (see Mehmet Hasan Altan v. Turkey, no. 13237/17, § 94, 20 March 2018, and Yüksel Yalçınkaya, cited above, § 213; see also paragraph 45 below).

3. ALLEGED VIOLATION OF ARTICLES 7 AND 6 § 1 OF THE CONVENTION

27. The applicants complained that their trials and convictions under Article 314 § 2 of the Criminal Code for membership of the FETÖ/PDY had violated the principle of no punishment without law under Article 7 of the Convention as well as the right to a fair trial under Article 6 § 1, the relevant parts of which read as follows:

Article 7

“1. No one shall be held guilty of any criminal offence on account of any act or omission which did not constitute a criminal offence under national or international law at the time when it was committed. Nor shall a heavier penalty be imposed than the one that was applicable at the time the criminal offence was committed.

...”

Article 6

“1. In the determination of ... any criminal charge against him, everyone is entitled to a fair ... hearing ... by [a] tribunal established by law ...”

1. Admissibility

28. The Court notes that these complaints are neither manifestly ill‑founded nor inadmissible on any other grounds listed in Article 35 of the Convention. They must therefore be declared admissible.

2. Merits
   1. The parties’ submissions

29. The applicants mainly complained before the Court that their convictions for membership of an armed terrorist organisation had not been foreseeable as required under Article 7 of the Convention. They argued in that connection that the acts that had formed the basis of their convictions had been lawful at the relevant time. Holding them criminally liable for those acts – and finding that the use of ByLock had sufficed alone to meet all the constituent requirements of the offence of membership of an armed terrorist organisation – entailed an extensive and arbitrary interpretation of the relevant laws, in violation of the principle of no punishment without law enshrined in Article 7 of the Convention. They further complained, under Article 6 § 1, of various alleged irregularities in the collection and admission in evidence of the ByLock data, as well as of the difficulties encountered in challenging them and the inadequacy of the reasoning in the courts’ decisions vis-à-vis that evidence, which in their opinion had rendered their trials unfair.

30. At the time notice of the present applications was given to the respondent Government by a Chamber of the Second Section, the Government were informed that the Court did not, in principle, require any observations on these applications, since the issues raised appeared to be the subject of well-established case-law of the Court by virtue of its findings in Yüksel Yalçınkaya (cited above, §§ 237-356). The Government were nevertheless advised that they had the option, if they so wished, of submitting observations on the applicants’ complaints under Articles 7 and 6 § 1, to the extent that such observations referred essentially to the factual aspects of the applications, and not to preliminary objections or legal issues already decided by the Court. The Government’s observations, once received, were transmitted to the applicants for information. Given the nature of the legal issues under consideration, which appeared to be the subject of well‑established case-law of the Court, the applicants were informed that no written observations were required on their part in response.

31. In their observations, the Government submitted at the outset that while notice of the present applications had been given to them as raising issues similar to those addressed by the Court in Yüksel Yalçınkaya (cited above), the Court’s considerations in that judgment had related to the specific facts of that case. They argued that the Court should therefore refrain from extrapolating the findings made therein to the present applications, which would risk overlooking the unique characteristics of the latter, and invited the Court to assess the criminal proceedings conducted against each applicant on the basis of their own particular circumstances.

32. The Government stressed in that regard that the convictions in the present applications had not been based solely on the applicants’ use of the ByLock application but had involved a wide variety of other evidence, not all of which had been subject to assessment in Yüksel Yalçınkaya (cited above; see the evidence noted in paragraph 14 above). The domestic courts, which had enjoyed direct contact with the evidence at issue, had established each applicant’s membership of the armed terrorist organisation on an individual basis following a careful assessment of all the elements in their specific case files. It therefore fell on the Court to take into consideration the individualised assessments carried out at the domestic level so as to avoid a superficial and stereotypical examination based solely on the findings in Yüksel Yalçınkaya (cited above).

33. As concerns specifically the applicants’ complaints under Articles 7 and 6 § 1 resulting from the decisive weight attached to the evidence establishing the use of ByLock, the Government challenged those complaints largely on the basis of the same arguments as advanced before the Grand Chamber in Yüksel Yalçınkaya (cited above, §§ 227-36 and 289‑99). In particular, the Government disagreed with the Court’s assessment in Yüksel Yalçınkaya (cited above) that the domestic judicial authorities’ approach to the use of ByLock – as proving on its own the material and mental elements of the offence of membership of an armed terrorist organisation – constituted an expansive interpretation of Article 314 of the Criminal Code. In their view,

“... it is possible for the domestic courts to conclude that if a person has been found to have downloaded and used the Bylock messaging application used exclusively by the FETÖ/PDY, despite all technical difficulties, this shows that such a person fully submitted to the will of the organisation and therefore that the applicant is a member of an armed terrorist organisation and that the necessary mental link exists for the establishment of the criminal liability.”

34. The Government further emphasised that unlike in Yüksel Yalçınkaya (cited above, §§ 98 and 107), the detailed ByLock findings and evaluation reports pertaining to the applicants – some of which included the content of the decrypted communications over the application – were included in their case files, and that the applicants were given access to all the information obtained and reports prepared by the authorities regarding their use of ByLock.

2. The Court’s assessment

35. The Court notes, and the parties did not dispute, that all the applicants in the present case were identified as users of the ByLock application. Nor is there any disagreement between the parties as to the probative value accorded to the use of that application by the domestic courts in determining an individual’s membership of the FETÖ/PDY, as examined at length in Yüksel Yalçınkaya (cited above, §§ 257 and 262-71). It remains to be determined, however, whether there are any elements in the case files that distinguish the present applications from Yüksel Yalçınkaya (cited above) and that require the Court to reach a different conclusion under Articles 7 and 6 § 1.

36. The Court indeed notes, as also pointed out by the Government, that the evidence in respect of some of the applicants included material that was not at issue in Yüksel Yalçınkaya (cited above), as noted in paragraph 16 above. That being said, having examined all the material and arguments submitted to it, the Court finds no reason in the present case to depart from its findings in Yüksel Yalçınkaya (cited above), for the reasons indicated below.

37. It notes in this connection that the finding of violations under Articles 7 and 6 § 1 of the Convention in Yüksel Yalçınkaya (cited above) had resulted notably from the domestic courts’ characterisation of the use of ByLock and the uniform and global approach adopted by the Turkish judiciary vis-à-vis the ByLock evidence (ibid., §§ 364, 413 and 414). Under that approach, anyone whose use of ByLock was established by the domestic courts could, in principle, be convicted on that sole basis of membership of an armed terrorist organisation pursuant to Article 314 § 2 of the Criminal Code. This was because all of the constituent elements of the relevant offence were considered to be manifested through an accused’s use of ByLock (ibid., § 262); the domestic court’s interpretation had in practice the effect of equating the mere use of ByLock with knowingly and willingly being a member of an armed terrorist organisation (ibid., § 267).

38. It therefore follows, as also underlined in Yüksel Yalçınkaya (cited above, § 414), that the situation that led to a finding of a violation of Articles 7 and 6 § 1 of the Convention in that case was not prompted by an isolated incident or attributable to the particular turn of events specific to the facts of that case; it may rather be regarded as having stemmed from a systemic problem that has affected – and remains capable of affecting – a large number of persons. This is evidenced by the fact that, following the Court’s judgment in Yüksel Yalçınkaya (cited above), the Court has already given notice to the respondent Government of 5,000 similar applications, and thousands more are still accumulating on its docket.

39. The Court does not rule out that there may be other evidence in respect of some of the applicants that may demonstrate, alone or cumulatively, their organic link with the FETÖ/PDY based on the continuity, diversity and intensity of their activities and their submission to its hierarchy as required under the Court of Cassation’s case-law (ibid., § 184) and thus secure their conviction as charged. The fact nevertheless remains, and the Government have reaffirmed in their submissions (see paragraph 33 above), that the establishment of the mere use of ByLock would serve, on its own, as conclusive proof of the presence of all of the constituent elements of the crime of membership of an armed terrorist organisation as defined in domestic law, irrespective of the content of the messages exchanged or the identity of the persons with whom the exchanges were made, or whether there was any other evidence in the case file (see Yüksel Yalçınkaya, cited above, §§ 257, 258, 262 and 263). The Court has declared this approach of the domestic courts, which effectively imputed objective liability to the users of ByLock, to be in contravention of the principle of legality safeguarded under Article 7 of the Convention (ibid., §§ 271 and 272), and it sees no reason to find otherwise in the present case.

40. The Court observes, in particular, that while the Government referred to the detailed ByLock findings and evaluation reports obtained in respect of some of the applicants which contained information, inter alia, regarding the decrypted content of their communications over the ByLock application, such content was either not available in the applicants’ files as alleged, or was relied on for the sole purpose of verifying the use of ByLock that had already been established by other means; the domestic courts did not take it into consideration in and of itself to demonstrate an applicant’s organic and hierarchical link to the organisation. On the contrary, the judgments against some of the applicants expressly indicated that it was not necessary to wait for the submission of the decrypted ByLock content into the case file, since the establishment of the use of that application, independent of the nature and content of the use, would suffice for conviction. That finding was indeed consistent with the Court of Cassation’s ruling that while information regarding the content of the communications and the persons with whom those communications were made could be useful for determining a person’s actual position within the structure of the terrorist organisation, it was not necessary for establishing their membership of that organisation within the meaning of Article 314 § 2 of the Criminal Code (ibid., §§ 160 and 258).

41. In these circumstances, the question whether, but for the decisive weight attributed to the use of ByLock, the evidence against the applicants – including any concrete content retrieved from ByLock messages – would have sufficed for their conviction for the same offence in a reasonably foreseeable manner is precisely for the domestic courts to determine in the light of the principles enunciated in Yüksel Yalçınkaya (cited above), and not for the Court to speculate. The recognition of the domestic courts’ primary responsibility in this regard is not only dictated by the Court’s limited role and capacity as an international tribunal as regards the interpretation of domestic legislation and the assessment of the facts and their legal classification in a particular case (ibid., § 265, and the cases cited therein), but is also in keeping with the fundamental tenets of the principle of subsidiarity that underpins the Convention system. The limitations of the Court’s capacity in this regard are all the more evident given the scale and magnitude of the problem, as evidenced by the sheer number of similar cases pending before it as mentioned in paragraph 38 above, which require resolution at the domestic level.

42. The Court would further note, as concerns specifically the applicants’ allegations under Article 6 § 1 of the Convention, that the criminal proceedings conducted separately against each applicant may indeed have shown differences in certain procedural respects, depending mainly on the evidence produced for or against the applicant and the administration of such evidence. However, irrespective of the possible particularities of each file, the domestic courts’ uniform and global approach to the use of ByLock has effectively defined the procedural framework of the criminal proceedings at issue, which have therefore suffered from the main shortcomings identified in Yüksel Yalçınkaya (cited above, § 345) as follows:

“In the Court’s view, the domestic courts’ failure to put in place appropriate safeguards vis‑à‑vis the key piece of evidence at issue to enable the applicants to challenge them effectively, to address the salient issues lying at the core of the case and to provide reasons justifying their decisions was incompatible with the very essence of the applicants’ procedural rights under Article 6 § 1.”

43. The Court stresses in this regard that independent of the nature and extent of the material in the applicants’ criminal case files, the contention that they had used the ByLock application for organisational purposes was not, and did not need to be, based on any specific factual findings made in their regard, such as the discovery of incriminating ByLock content or other information suggesting a hierarchical link. It was rather subsumed under the findings made primarily by the MİT based on the data it had obtained from the ByLock server, and subsequently embraced in the landmark judgments of the Court of Cassation, that ByLock had been used “exclusively” by the members of the FETÖ/PDY (ibid., §§ 338 and 340). Those findings suffered, however, from some “palpable lacunae” as pointed out by the Court in Yüksel Yalçınkaya (cited above, § 340), which the domestic courts had failed to address in their judgments pertaining to the applicants or elsewhere and which gave rise to concerns of automaticity in the processing of cases involving the use of ByLock (ibid., § 266). The Court repeats at this juncture that in view of the importance of duly reasoned decisions for the proper administration of justice, the domestic courts’ silence on vital matters that went to the heart of the case raised well-founded misgivings regarding the fairness of the proceedings (ibid., § 341).

44. Nor can the Court discern on the basis of the material before it that the domestic courts provided the applicants with a genuine opportunity to conduct their defence in an effective manner and on an equal footing with the prosecution as required under Article 6 § 1. The Court finds, for the reasons set out in Yüksel Yalçınkaya (cited above, §§ 324-41), that the applicants’ ability to challenge the data regarding their use of ByLock, including as regards the relevance and significance attributed to those data as well as their integrity, and to influence the outcome of the proceedings was considerably diminished. The Court takes note of the Government’s argument that the applicants had available to them all the ByLock reports relied on by the domestic courts in the criminal proceedings. That said, and as clearly indicated in Yüksel Yalçınkaya (cited above, §§ 326 and 327), the availability of those particular reports to the applicants, as important as it might have been, was not determinative of the question whether the applicants’ defence rights vis-à-vis the ByLock evidence were duly respected. The Court reiterates here the critical importance of the ByLock data obtained from the server to the applicants’ cases beyond the question of their personal use of that application (as established in Yüksel Yalçınkaya, cited above, §§ 328 and 333).

45. Having regard to the foregoing, the Court sees no reason in the present case to depart from the findings made in Yüksel Yalçınkaya (cited above) in the context of Article 6 § 1 of the Convention either. The Court accepts that the difficulties facing Türkiye in the aftermath of the attempted military coup of 15 July 2016 are undoubtedly a contextual factor which must be taken into account in cases such as the present one. Yet, for the reasons explained in detail in Yüksel Yalçınkaya (cited above, §§ 353-55), it has no basis on which to hold that the limitations on the applicants’ fair trial rights at issue were strictly required by the exigencies of the situation within the meaning of Article 15 of the Convention.

3. The Court’s conclusion

46. In view of the above considerations, the Court concludes that there has been a violation of Articles 7 and 6 § 1 of the Convention on the facts of the present case (ibid., §§ 272 and 356).

47. The Court would emphasise that its conclusion in this regard does not result from an indifference to the specific facts of each application as suggested by the Government (see paragraphs 31 and 32 above), but is rather a direct consequence of the domestic courts’ categorical approach to the use of ByLock, which led to a finding of violations under Articles 7 and 6 § 1 in Yüksel Yalçınkaya (cited above, §§ 272 and 356, respectively).

4. OTHER ALLEGED VIOLATIONS OF THE CONVENTION

48. The Court notes that some of the applicants also lodged complaints under other provisions of the Convention, such as Articles 5, 8, 9, 10, 11 and 14, or raised complaints relating to other aspects of Article 6 § 1 (as in Yüksel Yalçınkaya, cited above, §§ 357, 368 and 374). However, having regard to the finding of violations under Articles 7 and 6 § 1 above (see paragraph 46), the Court considers that it has dealt with the main legal questions raised by the case and that there is no need to address the admissibility and merits of any remaining complaints (see, mutatis mutandis, Yüksel Yalçınkaya, cited above, §§ 365, 367 and 373, and Turan and Others v. Turkey, nos. 75805/16 and 426 others, § 98, 23 November 2021).

5. APPLICATION OF ARTICLE 41 OF THE CONVENTION

49. Article 41 of the Convention provides:

“If the Court finds that there has been a violation of the Convention or the Protocols thereto, and if the internal law of the High Contracting Party concerned allows only partial reparation to be made, the Court shall, if necessary, afford just satisfaction to the injured party.”

50. The Court reiterates at the outset that Article 41 of the Convention empowers it to afford the injured party such satisfaction as appears to it to be appropriate (see Karácsony and Others v. Hungary [GC], nos. 42461/13 and 44357/13, § 179, 17 May 2016). The Court also reiterates, however, that it is not its role under Article 41 to function akin to a domestic tort mechanism court in apportioning fault and compensatory damages (see Al Jedda v. the United Kingdom [GC], no. 27021/08, § 114, ECHR 2011). The Court is an international judicial authority contingent on the consent of the States signatory to the Convention, and its principal task is to secure respect for human rights, rather than compensate applicants’ losses minutely and exhaustively. Unlike in national jurisdictions, the emphasis of the Court’s activity is on passing public judgments that set human rights standards across Europe (see, mutatis mutandis, Goncharova and other “Privileged Pensioners” cases v. Russia, nos. 23113/08 and 68 others, § 22, 15 October 2009; Gaglione and Others v. Italy, nos. 45867/07 and 69 others, § 67, 21 December 2010; and Nosov and Others v. Russia, nos. 9117/04 and 10441/04, § 68, 20 February 2014). Accordingly, the awarding of sums of money to applicants by way of just satisfaction is not one of the Court’s main duties but is incidental to its task under Article 19 of the Convention of ensuring the observance by States of their obligations under the Convention (see, for instance, Nagmetov v. Russia [GC], no. 35589/08, § 64, 30 March 2017).

51. The Court notes in this connection that it enjoys a certain discretion in the exercise of the power conferred by Article 41, as is borne out by the adjective “just” and the phrase “if necessary” (see, for instance, Arvanitaki‑Roboti and Others v. Greece [GC], no. 27278/03, § 32, 15 February 2008). The exercise of such discretion encompasses such decisions as to refuse monetary compensation or to reduce the amount that it awards (see Nagmetov, cited above, § 74). The Court’s guiding principle in this regard is equity, which above all involves flexibility and an objective consideration of what is just, fair and reasonable in all the circumstances of the case, including not only the position of the applicant but the overall context in which the breach occurred (see Varnava and Others v. Turkey [GC], nos. 16064/90 and 8 others, § 224, ECHR 2009; Al-Jedda, cited above, § 114; and Turan and Others, cited above, §§ 102-04).

52. Turning to the case before it, the Court notes that when giving notice of the present applications, it informed the parties that the approach to just satisfaction would likely be based on the Court’s practice in cases raising repetitive issues, and in particular on the Article 41 indications in Yüksel Yalçınkaya (cited above, §§ 420-32). They were further informed that the applicants would therefore be exempt from the requirement to submit a separate just satisfaction claim (see paragraphs 21 and 23 of the Practice Direction on Just Satisfaction Claims, issued by the President of the Court in accordance with Rule 32 of the Rules of Court on 28 March 2007 and amended on 9 June 2022). Some of the applicants did, nevertheless, request compensation in varying amounts, particularly in respect of non‑pecuniary damage and costs and expenses incurred before the domestic courts and the Court. The Government contested those claims as being unsubstantiated and excessive.

53. The Court considers, for the reasons explained in Yüksel Yalçınkaya (cited above, §§ 412, 424 and 425), that a finding of violations under Articles 7 and 6 § 1 of the Convention can be regarded as sufficient just satisfaction in respect of any non-pecuniary damage sustained by the applicants in the present case. It notes in this regard that the applicants have the possibility under Article 311 § 1 (f) of the Code of Criminal Procedure to have the domestic proceedings reopened following the delivery of the present judgment (ibid., § 411), and that the reopening of the proceedings in accordance with the requirements of the Convention provisions at issue in the present case would in principle constitute the most appropriate form of redress, should they so request. This is without prejudice to any general measures that may be required to prevent or redress other similar violations (ibid., § 412).

54. As for costs and expenses, according to the Court’s case‑law, an applicant is entitled to the reimbursement of costs and expenses only in so far as it has been shown that these have been actually and necessarily incurred and are reasonable as to quantum (see, for example, H.F. and Others v. France [GC], nos. 24384/19 and 44234/20, § 291, 14 September 2022). The Court notes that, in view of its well-established case-law on the legal issues arising in the present case, the domestic courts’ approach to the use of ByLock is capable of giving rise to a large number of violations of the nature found in Yüksel Yalçınkaya (cited above) and now in the present case in respect of 239 applications. The Court is mindful that the present applications were all submitted to it prior to the delivery of the judgment in Yüksel Yalçınkaya (cited above) – that is, prior to the development of its well‑established case-law on the legal issues concerned. However, irrespective of when they were submitted, it remains the case that they all related to the same fundamental systemic problem under Articles 7 and 6 § 1 of the Convention, which the applicants complained of in a uniform and standardised manner both before the domestic courts and subsequently before the Court, thus allowing the Court to process them as repetitive applications without further input from the applicants. The applicants were, therefore, not requested to submit written observations or just satisfaction claims in the present case.

55. In these circumstances, and having regard to its practice in cases raising systemic issues that generate a large number of repetitive applications, as well as to the principles established in its case-law, as noted in paragraphs 50 and 51 above, the Court considers that it is not justified to make any awards for costs and expenses in respect of follow-up applications of this type (see, mutatis mutandis, Greens and M.T. v. the United Kingdom, nos. 60041/08 and 60054/08, §§ 118 and 120, ECHR 2010 (extracts); Firth and Others v. the United Kingdom, nos. 47784/09 and 9 others, § 22, 12 August 2014; Zelenchuk and Tsytsyura v. Ukraine, nos. 846/16 and 1075/16, § 161, 22 May 2018; Alekseyev and Others v. Russia, nos. 14988/09 and 50 others, § 32, 27 November 2018; and Tingarov and Others v. Bulgaria, no. 42286/21, § 25, 10 October 2023).

56. The Court therefore declines to make any award in respect of costs and expenses in the present case.

FOR THESE REASONS, THE COURT,

1. Decides, unanimously, to join the applications;
2. Declares, unanimously, the applicants’ complaints that their trials and convictions for membership of the FETÖ/PDY had violated the principle of no punishment without law under Article 7 of the Convention and the right to a fair trial under Article 6 § 1 – as concerns the rights of the defence in respect of the evidence underlying the conviction – admissible;
3. Holds, by six votes to one, that there has been a violation of Article 7 of the Convention;
4. Holds, by six votes to one, that there has been a violation of Article 6 § 1 of the Convention;
5. Holds, unanimously, that there is no need to examine the admissibility and merits of the applicants’ remaining complaints;
6. Holds, unanimously, that the finding of a violation constitutes in itself sufficient just satisfaction for any non-pecuniary damage sustained by the applicants;
7. Dismisses, by a majority, the remainder of any claim made by the applicants for just satisfaction.

Done in English, and notified in writing on 22 July 2025, pursuant to Rule 77 §§ 2 and 3 of the Rules of Court.

Hasan Bakırcı Arnfinn Bårdsen
Registrar President

In accordance with Article 45 § 2 of the Convention and Rule 74 § 2 of the Rules of Court, the following separate opinions are annexed to this judgment:

(a) Partly concurring, partly dissenting opinion of Judge Arnardóttir;

(b) Partly dissenting opinion of Judge Yüksel.

PARTLY CONCURRING, PARTLY DISSENTING OPINION OF JUDGE ARNARDÓTTIR

1. The key legal issues raised by the applicants in the present case were examined by the Grand Chamber of the Court in Yüksel Yalçınkaya v. Türkiye ([GC], no. 15669/20, 26 September 2023). As regards the findings of violations of Articles 6 § 1 and 7 of the Convention and just satisfaction in respect of non-pecuniary damage, I agree with the approach taken by the majority in the Chamber, which follows the one developed by the Grand Chamber. I note in this respect that even though I would have sided with the dissenters in Yüksel Yalçınkaya on the question of non-pecuniary damage, I find myself compelled to follow the Grand Chamber judgment.

2. This case is marked by the fact that there are currently some 10,000 applications pending against Türkiye that raise the same key legal questions as those dealt with in the Yüksel Yalçınkaya judgment. Consequently, the individual applications at issue were communicated to the Government without requiring written observations. The Court also informed the applicants that the approach to just satisfaction would likely be based on the Court’s practice in cases raising repetitive issues, and in particular on the Article 41 indications in Yüksel Yalçınkaya. I note that the Grand Chamber in Yüksel Yalçınkaya made an award in respect of the costs and expenses incurred by the applicant domestically and before the Court. However, notwithstanding the above indications, given in the communication letters to the applicants, and the findings of the Grand Chamber, the majority in the Chamber decided not to make any award for costs and expenses to the applicants in the present case. I respectfully disagree and was therefore unable to vote with the majority on item 7 of the operative part of the present judgment.

3. I note in this connection that the facts at issue in the case-law cited by the majority in support of their approach were far from comparable to the facts in the present case. In the judgments cited, where the applicants were in fact denied an award for costs and expenses, they had either themselves secured a judgment in their favour by the Court before lodging 51 similar applications subsequently (see Alekseyev and Others v. Russia, nos. 14988/09 and 50 others, 27 November 2018) or applied to the Court years after the delivery of its leading judgments on the relevant issue, so that the lodging of their applications was considered so “straightforward” that it “did not require legal assistance” (see Firth and Others v. the United Kingdom, nos. 47784/09 and 9 others, § 21, 12 August 2014, and Tingarov and Others v. Bulgaria, no. 42286/21, § 24, 10 October 2023).

4. By comparison, as acknowledged by the majority, the applicants in the present case had lodged their applications before the Grand Chamber delivered its judgment in the Yüksel Yalçınkaya case. As evidenced by the relinquishment of that case to the Grand Chamber, this was clearly not a “straightforward” task at the time. The question whether the applicants pleaded in a uniform and standardised manner domestically and before the Court does not change anything in this respect (compare Varnava and Others v. Turkey [GC], nos. 16064/90 and 8 others, §§ 229-30, ECHR 2009). In my opinion, therefore, in so far as the applicants sought legal assistance in exhausting domestic remedies and lodging their applications with the Court, a reasonable amount was “necessarily incurred” in legal costs and expenses, which should have been awarded.

5. I acknowledge that the Court may, as a matter of judicial policy, opt to process repetitive cases arising out of the same systemic problem in a simplified and standardised manner to avoid jeopardising the long-term effectiveness of the Convention system and the Court’s key role of passing public judgments that set human rights standards across Europe. I can, therefore, agree with the Court’s approach in the present case of focusing its efforts on the question whether there was a violation of Articles 6 § 1 and 7 of the Convention on account of the domestic courts’ categorical approach to the use of the ByLock application, leaving unexamined the other complaints raised (see paragraph 48 of the judgment). I do not see, however, how following the approach to just satisfaction developed in Yüksel Yalçınkaya would have posed any threat of the above kind in the present case, or, for that matter, in any forthcoming follow-up cases lodged with the Court before the delivery of that judgment.

6. I also recognise that the Court is an international judicial authority contingent on the consent of the States signatory to the Convention, and that its principal task is to secure respect for human rights, rather than compensate applicants’ losses minutely and exhaustively. The award of just satisfaction under Article 41 of the Convention is therefore not one of the Court’s main tasks, but is incidental to its task under Article 19 of ensuring the observance by States of their Convention obligations. In the final analysis, however, acknowledging the limits of the Court’s role and function in this respect should not in my opinion translate – at the direct expense of the injured parties – into a wholesale exemption from any responsibility under Article 41 for Contracting States engaged in human rights violations of the kind and to the extent involved in the present case.

PARTLY DISSENTING OPINION OF JUDGE YÜKSEL

Since I maintain the legal views expressed in my dissenting opinions annexed to the judgment in Yüksel Yalçınkaya v. Türkiye ([GC], no. 15669/20, 26 September 2023), upon which the present judgment mainly relies, I respectfully disagree with the finding of a violation of Articles 6 and 7 of the Convention in the present case.

APPENDIX

List of cases: