Although the ByLock application allows communication through the computer server, the ByLock information and data are fully related to communication and they can be used in the criminal proceeding provided that they are obtained in accordance with the Article 135 of Turkish Code of Criminal Procedure (TCCP). However, 16th Criminal Chamber and Joint Criminal Chambers of the Court of Cassation have carried out their examination pursuant to Article 134 of TCCP due to the fact that the Bylock information is registered in a host computer. Although this method is considered not to be correct, starting from the establishment of the Court of Cassation, the study dwells with the lawfulness of obtaining Bylock information which is carried out under article 134 of TCCP and whose conditions are not satisfied.
In accordance with article 134 of TCCP, in order to perform any search, copying and seizure on the computer programs and databases, it is legally required a judicial decision for carrying out the procedures (search, copying and seizure) on the digital materials, based on the grounds that a judicial investigation is initiated and that it is not possible to obtain the evidence by other means. In addition, due to the fact that Bylock server is in another country, the proceedings to be performed should be in conformity with the Law no. 6706 on International Judicial Cooperation in Criminal Matters. Since the application in question allows communication in the Internet environment, the evidence to be obtained should be in compliance with the Electronic Communication Law No. 5809.
The study consists of four chapters. The first chapter is on the Bylock application and its features as well as the method of obtaining evidence through information systems. The second chapter concerns the lawfulness of the seizure of the Bylock server. The third chapter is on the evidential value of Bylock information in the context of court decisions, and on the assessments of those decisions. The fourth and final chapter is to relate the review of the Bylock information in the light of the European Convention on Human Rights, and the issues that should be determined by the courts related to Bylock.