Introduction
In September 2023, the Grand Chamber of the European Court of Human Rights (ECtHR) delivered its judgment in Yalçınkaya v. Türkiye. The judgment did more than decide one man’s case. It identified a systemic defect in Turkey’s post-2016 mass prosecutions. Turkish courts had used ByLock messaging-app data as near-automatic proof of membership in a terrorist organization. They rarely asked whether the accused had actually used the app for organizational, clandestine communication. The ECtHR found violations of Article 7 (no punishment without law) and Article 6 §§ 1 and 3 (equality of arms and adversarial proceedings). Domestic courts, it held, had treated ByLock detection as dispositive rather than as one piece of evidence requiring individualized assessment.
Two years on, the Turkish Constitutional Court (TCC) has not adopted that finding. Starting with Ali Bayram İskender (GK, B. No: 2020/31370, 25/9/2025), and now repeated in a growing line of cases including Mesut Yaşar and others (B. No: 2024/69117, 3/3/2026), the TCC has recast the defect as something narrower: a violation of the right to a reasoned decision under Article 36. On this theory, domestic courts simply failed to address applicants’ individual objections about organizational ByLock use. That is not a small shift in wording. It is a different legal theory, and it has consequences now visible in first-instance case files across the country.
Turkey’s Non-Compliance with Yalçınkaya Itself
The TCC’s approach cannot be separated from Turkey’s wider refusal to give effect to Yalçınkaya — including in the case of Mr. Yalçınkaya himself. After the Grand Chamber judgment, he was retried domestically. The Kayseri court did not acquit him, nor did it genuinely reassess whether the ByLock evidence was individually sufficient, as Strasbourg required. It reconvicted him, on appeal (istinaf) as well, on grounds substantially identical to those the Grand Chamber had already found incompatible with Articles 6 and 7. The applicant whose case exposed the systemic defect was run back through the same evidentiary logic the ECtHR condemned. This is the clearest sign that the judgment has not been implemented — not even at the level of individual redress, let alone through general measures.
The Grand Chamber was explicit that the violations were systemic, not case-specific. At the time, roughly 8,000 applications were pending raising materially identical Article 6/7 complaints. Turkish authorities had themselves identified around 100,000 alleged ByLock users, so the pool of future applicants remains vast. Under Article 46 ECHR, this systemic finding obliges Turkey to adopt general measures addressing how ByLock data is handled, disclosed, verified, and used as evidence. It is not enough to resolve individual files one by one. No such general measures have been adopted.
The docket since 2023 shows the problem growing rather than shrinking:
- July 2025 — Demirhan and Others v. Türkiye (applications nos. 1595/20 and 238 others): further violations of Article 7 and Article 6 § 1.
- 16 December 2025 — Bozyokuş and Others, Karslı and Others, and Seyhan and Others v. Türkiye: a combined 2,420 applications, again finding violations of Article 7 and/or Article 6 § 1.
- 23 June 2026 — Çali and Others, Dönmez and Others, and Kılıçarslan and Others v. Türkiye: a further 893 applications. The ECtHR expressly reaffirmed the Yalçınkaya case-law and underlined that the defect is systemic, not isolated.
Together, these judgments cover well over 3,500 applicants decided after Yalçınkaya alone, on top of the thousands still pending. Meanwhile, Turkey continues to arrest, prosecute, and convict people for terrorism offences on the basis of alleged ByLock usage, under practices the Grand Chamber already found unlawful. Seen against this record, the TCC’s narrower reasoned-decision doctrine looks less like judicial caution. It looks like a domestic track running alongside Strasbourg’s supervision, not in service of it.
There is also a gap on the Strasbourg side. Given the scale — a judgment that could touch, on Turkey’s own figures, up to 100,000 people, likely one of the most consequential rulings in the Court’s history by sheer numbers — Council of Europe bodies responsible for supervising execution under Article 46 § 2 have not yet scrutinized Turkey’s implementation record at a level matching that scale. This leaves a supervisory gap at the international level that mirrors the gap at the domestic level. Without a clear, enforced standard from Strasbourg or from Ankara, individual criminal chambers are left to decide for themselves how far, if at all, Yalçınkaya applies to the case in front of them.
A Narrower Remedy, Deliberately Chosen
The distinction between the two legal theories matters because they carry very different scopes of relief. A finding that Article 7 and equality-of-arms guarantees were structurally violated — the ECtHR’s actual holding — puts the legality of the whole ByLock evidentiary regime in question. It would require Turkish courts to revisit the sufficiency and admissibility of that evidence across the board. A finding confined to the reasoning of individual decisions does none of that. It leaves the underlying evidentiary framework untouched and asks only for a fuller written explanation before conviction on the same evidence. The TCC’s own reasoning in Mesut Yaşar makes the narrowing explicit: having found a reasoned-decision violation, it stated that the equality-of-arms and legality-of-offence complaints required “no separate examination,” folding them into the narrower holding rather than deciding them on their own terms.
The result is a body of TCC case law that looks like compliance. Violations are found. Retrials are ordered. Article 153 of the Constitution is invoked to make the rulings final and binding. But the substantive legal problem Strasbourg identified is never actually confronted. This matches what a June 2025 joint briefing by Human Rights Watch, the International Commission of Jurists, and the Turkey Human Rights Litigation Support Project called “pretend compliance” — cooperation with international human rights standards that is hollow in substance. The TCC president’s own public statement, that “ultimately, the courts in Türkiye will make the decision,” fits this pattern rather than departing from it.
From Doctrinal Containment to Judicial Anarchy
This containment strategy does not just fail to fully vindicate Convention rights. It actively produces the chaos now visible in the implementation record.
The TCC’s reasoned-decision theory is doctrinally new and left deliberately vague. It is a workaround, not a principled application of settled retrial criteria. That leaves first-instance and appellate courts without a stable, binding template for what compliance actually requires. Courts asked to reopen ByLock convictions on this basis have responded in strikingly different ways:
- Ankara 15. High Criminal Court, in the İbrahim Kaya file (decision of 1 September 2026), refused even to open a retrial. It relied on a 1994 Yargıtay precedent that predates the current Code of Criminal Procedure (CMK, in force since 2004). It applied to a constitutionally mandated TCC remedy the same discretionary “seriousness” threshold used to screen ordinary, party-initiated retrial petitions under CMK Article 311 — a category TCC-ordered retrials, created by the 2010 constitutional amendment on individual application, do not belong to.
- İstanbul 33. High Criminal Court, has likewise refused to recognize the Mesut Yaşar ve diğerleri line of decisions at all.
- The Ankara Regional Court of Appeal and the Court of Cassation have also refused to comply with the Yalcinkaya judgment findings in a case in which 12 lawyers were convicted and sentenced to a total of 80 years in prison.
In the infamous Gezi Part Trial, the Istanbul 13th High Criminal Court and the Court of Cassation refused outright to implement two binding TCC violation judgments ordering release and retrial of Can Atalay and Tayfun Kahraman. They accused the Constitutional Court of “usurping authority” and acting as a “super appellate court”.
None of these courts is applying a shared standard, because none exists. By grounding relief in an ad hoc reasoned-decision theory instead of the ECtHR’s clear Article 7 and equality-of-arms findings, the TCC has left the domestic judiciary without a workable compliance template. First-instance courts have been left to write their own — in Ankara’s case, borrowing one from a legal regime that no longer exists. The Constitutional Court’s retreat has not produced order through minimalism. It has produced a fragmented, unpredictable landscape, where the outcome of a retrial application depends less on the law than on which chamber, in which city, happens to hear it.
Structural Incentives, Not Isolated Failures
This is not simply a coordination problem that time will fix. Thirteen of the TCC’s fifteen judges are directly appointed by President Erdoğan. That gives the Court every incentive to avoid a ruling that would force Turkish courts to unwind the evidentiary basis of tens of thousands of terrorism convictions at once. A narrow, reasoning-focused remedy lets the Court signal responsiveness to Strasbourg, satisfy the formal requirement that individual application serve as an effective domestic remedy under Article 35 ECHR, and avoid a direct confrontation with the executive over the ByLock prosecutions. For a captured court operating under political constraint, this is a rational strategy. But it is, for that same reason, incompatible with the TCC’s constitutional role as guarantor of binding, uniform, rights-protective adjudication under Article 153.
The result is internally contradictory case law — the same pattern the ECtHR itself once observed in the TCC’s post-2016 jurisprudence more broadly. Compare Mehmet Altan/Şahin Alpay with the Court’s later refusal to extend the same protection in Ahmet Altan, or compare Kavala with Yalçınkaya. Decisions that look similar on the surface reach incompatible outcomes depending on how politically sensitive the case is. Lower courts are left without a genuinely precedential body of law to follow, even when they want to comply in good faith.
The Enforcement Consequence
The practical result is that Yalçınkaya — a Grand Chamber judgment, binding under Article 46 ECHR and subject to enhanced supervision by the Committee of Ministers — is not being enforced in Turkey in the form Strasbourg actually adopted. It has passed through a domestic intermediary that substituted a narrower theory of its own. That intermediary’s own remedy is now being ignored, applied inconsistently, or openly defied by the courts meant to give it effect. Each stage compounds the last: Strasbourg’s judgment, the TCC’s narrowing of it, and first-instance non-compliance with even the narrowed version. The individual application mechanism was introduced in 2010 to serve as an effective domestic remedy under the ECtHR’s Uzun doctrine. It is being hollowed out — not through one dramatic confrontation, as in Atalay, but through a slower process: the TCC’s own retreat from principled adjudication, which strips away the doctrinal footing domestic courts would otherwise need to follow.
Conclusion
The TCC’s shift — from the legality and equality-of-arms defects Strasbourg identified in Yalçınkaya, to a narrower, self-authored reasoned-decision doctrine — is not a neutral technical choice. It is a containment tactic. It lets the Constitutional Court appear responsive to European human rights law while withholding the substantive relief that law actually requires. But containment carries a cost. Without a clear, principled remedy to enforce, first-instance courts have been left to improvise: citing obsolete precedent, ignoring binding TCC rulings outright, or treating individual application decisions as advisory rather than constitutionally binding under Article 153. The outcome is not the modest, executive-tolerable compliance the TCC may have wanted. It is a real crisis of legal certainty — a body of retrial law that now varies court by court, city by city, while the ECtHR’s actual findings in Yalçınkaya remain further from domestic implementation than at any point since the judgment was delivered.
Categories: Turkey Human Rights Blog