Turkey’s Constitutional Court has ruled that a terrorism conviction based on the use of the ByLock encrypted messaging app did not violate the principle of no punishment without law, despite a landmark European Court of Human Rights (ECtHR) ruling that found Turkey’s treatment of ByLock evidence violated the same principle.
In a unanimous decision concerning Derya Baş, the court found that the trial court’s interpretation of her conduct fell within the scope of the offense of membership in a terrorist organization and that its conclusions were neither arbitrary nor unfounded. Messages attributed to Baş were cited as evidence that she attended gatherings linked to the Gülen movement, collected donations and arranged newspaper subscriptions. The ruling, dated June 17, was published on July 24.
Baş was sentenced by the Antalya 8th High Criminal Court to more than six years in prison for membership in a terrorist organization, based primarily on police records indicating that she had used ByLock. The app, once widely available on Apple’s App Store and Google Play, is claimed by Turkish authorities to have been used as a secret communication tool by members of the Gülen movement.
Her conviction was upheld by an appeals court in 2018 and by the Supreme Court of Appeals in January 2023.
Turkish President Recep Tayyip Erdoğan has targeted the Gülen movement, a worldwide civic initiative inspired by the ideas of Muslim cleric Fethullah Gülen, who died in 2024, since corruption investigations in December 2013 implicated him as well as some members of his family and inner circle. He dismissed the probes as a Gülenist conspiracy and designated the movement as a terrorist organization in May 2016, intensifying a sweeping crackdown after the coup attempt in July of the same year that he accused Gülen of orchestrating. The movement denies involvement in the coup attempt or any terrorist activity.
Baş denied using ByLock and challenged the authenticity and reliability of the data attributed to her. In her application to the Constitutional Court, she said she had been punished for conduct that was not considered a crime when it occurred and that the lower courts had failed to adequately address her objections.
In its 2023 Grand Chamber judgment in Yüksel Yalçınkaya v. Türkiye, the ECtHR found that convictions based on ByLock use and other alleged Gülen-linked activities, such as having an account at a movement-affiliated bank, violated the rights to a fair trial, no punishment without law and freedom of association.
The ECtHR said Turkish courts had effectively equated ByLock use with knowingly and willingly belonging to a terrorist organization without separately establishing the intent required for the offense. It said this approach created an almost automatic presumption of guilt, effectively treating membership in a terrorist organization as an offense of strict liability.
The Strasbourg court also identified a systemic problem affecting thousands of similar convictions and called on Turkey to take general measures to address its courts’ treatment of ByLock evidence.
According to the latest figures from the justice ministry, more than 127,000 people have been convicted of alleged links to the movement since 2016, with 10,485 still in prison and legal proceedings ongoing against 83,404 individuals.
In addition to the thousands who were jailed, scores of other Gülen movement followers had to flee Turkey to avoid the government crackdown.
