Targeting a Social Group Through Mass Convictions in Turkey: A Brief Crimes Against Humanity Analysis

[Hakan Kaplankaya is a former Turkish diplomat, lawyer and instituDE member]

On 16 December 2025, the European Court of Human Rights (“ECtHR” or “the Court”) found violations of Articles 7 and/or 6 § 1 of the Convention in respect of 2,420 applications in Yalçınkaya follow-up cases. The applicants are (perceived) members of the Gülen Group, which has been targeted by the Turkish government over the past decade. The scale of the cases before the Court is striking. 

This post examines whether, in light of the high number of violations established by international adjudicatory mechanisms, the situation may also engage the applicability of international criminal law arising from the deprivation of liberty in violation of international law.

Factual Background 

The Gülen Group, previously regarded as an ally of the ruling party in Turkey between 2002 and 2013, became an enemy of the State after the 17-25 December graft probes targeting prominent figures within the ruling AKP.

In response, the Turkish government launched a campaign to tighten its control over the judiciary and to turn it into a punitive instrument against its critics. It established Criminal Peace Judgeships, which have been widely used to impose criminal measures such as pre-trial detention and the appointment of trustees—particularly targeting political opponents and members of the Gülen Group.

On 15 July 2016, a coup attempt unfolded, for which the Gülen Movement was held responsible, triggering a severe crackdown that amounted to persecution. Through a series of emergency decree-laws, over 130,000 public servants and one third of the judiciary were dismissed (for further information regarding the purge, see here); 174 media outlets, over 2,200 educational institutions, 15 universities, 29 trade unions, and more than 1,500 associations and foundations were closed, predominantly on grounds of affiliation with the Movement, with confiscated assets reportedly exceeding USD 50 billion. Mass criminal prosecutions on terrorism charges followed at an unprecedented scale: over 705,172 individuals were investigated, more than 332,884 detained, and over 125,000 convicted — on evidence that rarely demonstrated criminal or violent conduct.

UN Mechanisms’ Response to Persecution

The UN Working Group on Arbitrary Detention (WGAD) issued 26 opinions between June 2017 and November 2024 concerning allegations of arbitrary detention in Turkey or cases of individuals detained abroad and illegally transferred to Turkey. In these opinions, the WGAD consistently concluded that the detentions of Gülen Movement supporters were arbitrary, as they lacked a legal basis, arose from the exercise of rights and freedoms protected by the International Covenant on Civil and Political Rights (ICCPR), disregarded fair trial guarantees, and were carried out on discriminatory grounds based solely on perceived political opinions or alleged affiliation with the Gülen Group.

The most significant conclusion relevant to the present analysis is the WGAD’s finding of a pattern of discriminatory targeting of individuals alleged to have links with the Gülen Movement and its warning that, under certain circumstances, such systematic imprisonment may amount to crimes against humanity. However, it should be noted that the WGAD is not an international judicial body empowered to determine international criminal responsibility.

In Opinion No. 47/2020, concerning six Turkish citizens living in Kosovo who were illegally deported to Turkey, the WGAD stated:

“During the past three years, the Working Group has noted a significant increase in the number of cases brought before it concerning arbitrary detention in Turkey. The Working Group expresses grave concern about the pattern established by all these cases and recalls that, under certain circumstances, widespread or systematic imprisonment or other severe deprivation of liberty in violation of the rules of international law may constitute crimes against humanity.” (§ 101)

The WGAD reiterated this warning in its several subsequent opinions (51/2020, 67/2020, 84/2020, 3/2023, 29/2023 and 33/2024). 

The European Court of Human Right’s Findings

Regarding mass detentions based on alleged affiliation with the Gülen Group, the European Court of Human Rights first examined the cases of dismissed members of the judiciary ( Alparslan Altan, Erdal Tercan, Hakan Baş and Turan and Others, for a detailed analysis, see here). These applicants had been detained pursuant to the doctrine of flagrante delicto, which was used to bypass judicial tenure guarantees on the basis that membership in a terrorist organisation constituted a continuing offence. The Court ruled that their pre-trial detentions were unlawful due not only to the absence of a “reasonable suspicion” at the time of detention but also to the complete disregard of procedural safeguards applicable to magistrates.

As regards ordinary citizens, the first judgment specifically addressing the use of ByLock evidence in detention proceedings was the Akgün case. The Court held that there had been no reasonable suspicion that the applicant had committed the alleged offence. Following these leading cases, the Court began examining thousands of similar detention cases, which flooded its docket. By September 2025, the Court had found violations of Article 5 of the Convention in respect of approximately 3,851 applicants, most commonly under Article 5 §§ 1 and 1(c), either because the detention was unlawful or because it lacked reasonable suspicion.

Post-Yalçınkaya Cases

In the landmark judgment of Yalçınkaya v. Türkiye, delivered on 26 September 2023, the Court took a decisive stance against arbitrary and the systematic criminalisation of perceived affiliates of the Gülen Group. Central to the Court’s findings was the ‘automatic’ attribution of membership in a terrorist organisation based solely on the use of the ByLock messaging application. The Court held that this practice, which bypassed the requirement to establish specific actus reus (material elements) and mens rea (criminal intent) of the offence, violated the fundamental principle of maxim nullum crimen, nulla poena sine lege, and thus breached Article 7 of the Convention. The Court also found a violation of Article 6 § 1, emphasising serious deficiencies in the examination of ByLock evidence and noting that the applicant had not been genuinely heard by the domestic courts (§ 341). (For other comprehensive analysis of the case, see, here, here and here).

Characterising the violations identified in Yalçınkaya as systemic in nature, the Court acknowledged the unprecedented scale of the crisis, noting nearly 100,000 cases were predicated on identical legal issues (§§ 414–415). In response to this judicial backlog and the persistent ineffectiveness of domestic remedies, the Court subsequently communicated five clusters of one thousand cases (see Demirhan and Others § 38), each without requesting observations from the Government, thereby indicating that the examination would be largely procedural and that findings of violation were effectively presumed. In addition, the Court communicated a further 4,800 similar cases to the Turkish Government. Taken together, these measures demonstrate that the Court has already presumed Yalçınkaya-type violations in 9,800 cases.

The first Yalçınkaya follow-up judgment was delivered on 22 July 2025 in Demirhan and Others v. Türkiye, concerning 239 applicants (For detailed analysis, see here). As expected, the Court found violations of Articles 7 and 6 § 1 without undertaking an individualised analysis for each applicant. Notably, the Court expanded the scope of Yalçınkaya by covering a broad range of evidentiary material (§ 16).

On 16 December 2025, the Court delivered a second wave of Yalçınkaya follow-up judgments concerning 2,420 applications. In Karslı and Others, it found violations of Articles 7 and 6 § 1 for 1,436 applicants; in Bozyokuş and Others, a violation of Article 7 for 132 applicants; and in Seyhan and Others, a violation of Article 6 § 1 for 852 applicants. 

Although all cases are considered Yalçınkaya-type cases, in the latter two groups the Court refrained from conducting a detailed assessment of the exhaustion of domestic remedies with respect to the remaining Article, and confined its findings to a violation of Article 7 or Article 6 § 1, holding that the reopening of proceedings rendered examination of the remaining complaint unnecessary.

Turkish Judicial Practices as Crimes Against Humanity under Article 7 of the Rome Statute

Article 7 § 1 of the Rome Statute provides that, “when committed as part of a widespread or systematic attack directed against any civilian population and with knowledge of the attack”, certain acts constitute crimes against humanity. These acts include, inter alia, “imprisonment or other severe deprivation of physical liberty in violation of fundamental rules of international law” (Article 7 § 1(e)) and “persecution against any identifiable group or collectivity on political, racial, national, ethnic, cultural, religious, gender, or other grounds universally recognised as impermissible under international law” (Article 7 § 1(h)).

The requirement that an attack be “widespread or systematic” has been consistently interpreted in international criminal jurisprudence. The “widespread” character connotes the large-scale nature of the attack and the number of its victims. The “systematic” character signifies the organised nature of the acts and the improbability of their random occurrence (Prosecutor v. Kunarac et al., Trial Chamber §§ 428–429, Blaškić, Appeals Chamber, § 101). It is also noteworthy that the attack need not be military in nature and that the existence of a formal or written policy is not required, provided that the acts form part of an organised and recurrent course of conduct directed against a civilian population (Kunarac, Appeals Chamber, § 98; Blaškić, Trial Chamber, § 203, Blaškić, Appeals Chamber, § 120).

The scale of prosecutions described above demonstrates the widespread character of the Turkish State’s attack against the Gülen Group. It is worth noting that the Court described the judicial attack as “widespread” in Demirhan and Others (§ 13). Although the Court employs the notion of “widespread” in a flexible, descriptive manner to support its assessment of severity and the existence of systemic or structural issues, its usage nevertheless reflects—at least implicitly—the core understanding of “widespread” in international criminal law, denoting the large-scale nature of the attack, the high number of victims, and its broad geographical scope. UN WGAD opinions and ECtHR judgments together establish that more than 3,851 individuals were unlawfully detained. Moreover, the Court found that the convictions of 1,808 individuals violated the principle of nullum crimen sine lege, while 852 individuals were convicted following trials that substantively infringed the right to a fair trial. As emphasised in Yalçınkaya, these individuals were not genuinely heard, revealing a profound travesty of justice.

Accordingly, the findings of the UN mechanisms and the ECtHR lead to the conclusion that the Turkish State’s actions amount to imprisonment or severe deprivation of liberty in violation of fundamental rules of international law, within the meaning of Article 7 § 1 (e) of the Rome Statute. This is particularly so as the detentions and subsequent convictions did not stem from mere shortcomings in procedural safeguards, but rather from core violations, including the absence of reasonable suspicion and breaches of the principle of legality in criminal law. As such, they clearly meet the criterion of a violation of fundamental rules of international law.

Furthermore, the UK Home Office, the Dutch Ministry of Foreign Affairs, and the German Federal Office for Migration and Refugees recognise the Gülen Movement as a persecuted group under the 1951 Geneva Convention. Members of the Gülen Group have been granted refugee status in numerous democratic States on the basis of persecution or a well-founded fear of persecution in Turkey. Nevertheless, while the notion of “persecution” under international refugee law may lend support to the present analysis, it does not automatically satisfy the threshold required for “persecution” as a crime against humanity under Article 7 § 1 (h) of the Rome Statute, which requires an autonomous legal assessment.

The Gülen Movement was designated a terrorist organisation by Turkey’s National Security Council on 26 May 2016, two months before the coup attempt. The first final judicial decision confirming this designation was issued on 26 September 2017 (§ 155, Yalçınkaya). However, the governmental campaign against the Movement began as early as late 2013 and crystallised into a State policy after the coup attempt, implemented through the judiciary and law enforcement authorities.

Notably, the Gülen Movement is not classified as a terrorist organisation by any Council of Europe member State or any democratic State worldwide. Several UN Special Procedures mandate holders have stated that “… the designation of the Gülen Movement as a terrorist organization does not appear to meet the requirements of due process or satisfy the criteria outlined in the model definition” (AL TUR 5/2024, p.6). 

The Turkey Tribunal, an unofficial people’s tribunal presided over by François Tulkens, concluded in its legal opinion that acts of abduction and torture committed against Kurds and members of the Gülen Movement amounted to crimes against humanity, and subsequently submitted a communication to the ICC Prosecutor. Although the Tribunal did not focus on unlawful deprivation of liberty, its findings on the widespread or systematic nature of the attack against a civilian population are equally applicable to the crime against humanity of imprisonment. In the same vein, Dr. Kerem Gülay has argued that Turkish judicial practice appears to meet the threshold of crimes against humanity.  

Thus, the international response to the Turkish Government’s attack on the Gülen Group, which has been premised on a terrorism narrative, risks legitimising conduct that has been found to be unlawful.

Conclusion

Recent rulings of the European Court of Human Rights confirm that the scale of rights violations in Türkiye has reached an entrenched and systemic threshold. This volume of State-led persecution raises an inescapable question as to whether such acts may be classified as crimes against humanity under international law. Although Turkey is not a party to the Rome Statute, such conduct may nevertheless be punishable under domestic law, as suggested by Dr. Yeşil. Moreover, these actions remain subject to customary international law and the extraterritorial reach of universal jurisdiction. The possibility that such conduct may be prosecuted through universal jurisdiction mechanisms or give rise to Magnitsky-type sanctions further underscores the significance of this discussion. The targeting of a social group numbering in the hundreds of thousands on the territory of a founding member of the Council of Europe should be regarded as a matter that calls for the attention and responsibility of the international community.