Background
Thirty-four applicants were convicted in Turkey of membership in the FETÖ/PDY (Fetullahist Terror Organisation/Parallel State Structure), which Turkish authorities deemed responsible for the July 15, 2016 coup attempt. The domestic convictions were based decisively on the applicants’ use of ByLock, an encrypted messaging application, which the Turkish courts treated as independently sufficient for conviction under Article 314 § 2 of the Criminal Code for membership of an armed terrorist organization.
The applicants’ case files included supplementary evidence such as memberships in affiliated organizations, account activities at Bank Asya, possession of pro-FETÖ/PDY materials, participation in organized trips, donations to affiliated foundations, social media posts, residence in organization-affiliated dormitories, and communications through other messaging apps. However, in some cases, convictions were imposed without waiting for detailed ByLock findings or evaluation reports, on the sole ground that use of the application sufficed for conviction. The applicants’ challenges to their convictions before Turkey’s Constitutional Court were summarily dismissed as inadmissible.
The Court’s Holding
The European Court of Human Rights found a violation of Article 7 of the Convention (the principle of no punishment without law). The Court held that the domestic courts’ approach of treating the mere use of ByLock as conclusive proof of membership in an armed terrorist organization violated the principle of legality. This characterization effectively imputed objective liability to all users of ByLock, making it possible for any individual whose use of the application was established to be convicted on that sole basis, irrespective of the nature or content of their communications.
The Court rejected the Government’s argument that convictions in each case involved an individual assessment of varied evidence. It reasoned that the findings of violation in the prior case of Yüksel Yalçınkaya resulted not from isolated incidents but from a systemic judicial approach that potentially applied to everyone convicted for FETÖ/PDY membership based on ByLock use. While the Court did not rule out that other evidence might independently demonstrate an applicant’s organic link to the organization based on the continuity, diversity, and intensity of their activities, the critical problem was that establishment of mere ByLock use served as conclusive proof on its own. The Court declined to separately examine Article 6 § 1 (fair trial) complaints, finding the Article 7 violation sufficient to address the main legal questions raised.
Key Takeaways
- Use of a particular encrypted messaging application cannot constitute sole or conclusive proof of membership in a terrorist organization; such use alone violates the principle of legality enshrined in Article 7.
- Criminal liability for membership in a terrorist organization requires evidence demonstrating an organic link through continuity, diversity, and intensity of activities and submission to the organization’s hierarchy, not merely technological association.
- The principle of legality prohibits courts from treating technological evidence (such as app usage) as conclusively establishing all elements of a complex criminal offense without examining the content and context of communications.
- Applicants have the right under Turkish procedural law (Article 311 § 1(f) of the Code of Criminal Procedure) to seek reopening of their domestic proceedings in light of the principles established in this judgment.
Why It Matters
This judgment reinforces a critical protection in criminal law: individuals cannot be convicted of complex crimes based on technological association alone. The decision is particularly significant for national security prosecutions and counterterrorism efforts, as it clarifies that states cannot use mere use of designated apps or digital tools as proxies for proving organizational membership. The holding protects individuals from conviction based on circumstantial technological evidence while acknowledging that aggregated evidence of actual organizational involvement—contact patterns, communications content, activities, and organizational hierarchy submission—may still support conviction.
The judgment applies to a large group of 34 applicants and reflects an established line of authority (Yüksel Yalçınkaya, Demirhan and Others) that Turkey’s approach to ByLock-based convictions violates the Convention. It signals to member states that counterterrorism prosecutions must meet rigorous standards of individual culpability rather than rely on shortcuts based on use of particular technologies. The availability of domestic reopening procedures offers practical redress while establishing precedent that will affect future prosecutions involving technological evidence in terrorism cases throughout Europe and beyond.