The Turkish Constitutional Court zigzags and contradicts itself

Dr. Gökhan Güneş, human rights expert


The Turkish Constitutional Court (TCC), which is supposed to be the protector of the right to a fair trial and, in particular, the principle of “legal certainty”, an indispensable element of the same right, has turned into a judicial body which violates this principle frequently with its contradictory judgments. The most recent examples of these contradictory judgments are the Court’s  Esra Saraç Arslan[1] and Yusuf Çoban[2] judgements. In these two cases involving the use of the Bylock application, the General Assembly of the Constitutional Court delivered completely contradictory judgments only 2 months and 10 days apart.

In both of these cases:

  • The applicants said that they downloaded the Bylock application but did not use it for purposes of the Organisation[3],
  • The police enquiry report called Bylock Detection and Assessment Report (TDT)[4] was not brought into the case files, and
  • The judgment was delivered without having an expert witness examination.

However, while the Constitutional Court, in its decision on Esra Saraç Arslan, accepted that it was a mispleading that the Bylock TDT had not been brought into the file and that the decision to not have an expert examination was a violation of the principle of fair trial, in its decision on Yusuf Çoban it ruled the opposite and found the applicant’s complaints inadmissible being a “fourth-instance ” appeal.

Esra Saraç Arslan Judgment of the Constitutional Court

The applicant’s complaint mainly concerns the violation of the principles of equality of arms and adversarial proceedings on the grounds of the rejection of her request for an expert examination of the data regarding the Bylock-related evidence.

In her interrogation before the criminal judge of peace, the applicant stated that she had downloaded the Bylock programme from the Google Play Store out of curiosity but never used it. She then stated that she did not receive any instructions to actually use the programme, that she had nothing to do with the Organisation, that she had not added anyone as a contact in that programme, that no one who had added her either, and that she had neither received nor sent any messages.

The Court requested the following from the Chief Public Prosecutor’s Office: the HTS-CGNAT (internet traffic) data of the GSM line, the information about the mobile device used by the applicant, and the records containing the IP data regarding the day and time of access to the ByLock application servers. In accordance with the response to its request, the court decided to sentence the applicant – without bringing the Bylock detection and evaluation report (TDT[4]) to the file and without conducting an expert examination despite the applicant’s request. The 16th Criminal Chamber of the Court of Cassation, which considered the appeal, upheld the decision, taking into consideration the applicant’s statement (admitting that she had downloaded Bylock app) at the criminal judgeship of peace and the content of the file. As a result, the Court of Cassation did not find the failure to bring the TDT to the file effective to the outcome of the case on the grounds that the applicant’s admission.

TCC: The way We approach Bylock is not categorical!

The Constitutional Court disagreed with the way the Court of Cassation approached ByLock and stated that the approach of the Court of Cassation, the courts of first instance and itself towards Bylock should not be categorical. They referenced its Ferhat Kara judgment which was an attempt to set forth general principles regarding Bylock cases (Ferhat Kara, § 159).

What is meant by “categorical approach”?.

According to the TCC,  in judicial proceedings, it was not the downloading of the programme to the device, but the creating a user account in the application and its use for the purposes of the Organisation should be taken as evidence for conviction; what should be sought to be determined is whether the programme was used by the defendant for the purposes of the Organisation.

In other words, according to the Constitutional Court, the mere downloading of this application on a phone is not sufficient to prove the allegation of membership in a terrorist organisation. TCC alleges that this is the approach of both the Court of Cassation and itself.

Actual Situation in Current Trials and the Constitutional Court’s Categorical Approach

The words of the Constitutional Court are evidence of how removed it is from the realities of current criminal proceedings. In fact, there are countless convictions based solely on information and data prepared by the MİT and showing no more than that the Bylock app was downloaded. And the Court of Cassation’s case law on Bylock is the exact opposite of what TCC suggests.

Another problematic issue here is that the definition of “use for organisational purposes” is vague enough to allow arbitrary interpretation. For example, is it actually an organisational activity for a person to share a verse or a hadith, ask for prayers, or send messages about daily matters through the application? There are ongoing trials in which many people are being convicted for such content; this should never be sufficient for an accusation of membership in an armed organisation.

Is the Constitutional Court’s decision in Esra Saraç Arslan case which established a violation of the right to fair trial capable of preventing arbitrary imprisonments in Bylock cases?

The Constitutional Court accepted the refusal to carry out the expert examination procedure requested by the applicant in order to determine the accuracy and reliability of the Bylock enquiry report (detection and evaluation report / TDT) , and the CGNAT data (internet traffic records), both of which indicate that the defendant downloaded/used Bylock, has placed the applicant at a significant disadvantage in terms of the use of procedural possibilities against the prosecution.

This decision however does not address the root of the problem which is denying the Courts and defendants a digital copy of data obtained by the Turkish Intelligence Agency from the Bylock servers (‘Bylock servers’ data’). For 7 years, neither the Courts nor the defendants have been delivered a digital copy of data originating from Bylock servers which prevented them to examine the authenticity, reliability and lawfulness of it. Indeed, this data is being protected as a “sacred text by the Turkish Intelligence Agency.

Unfortunately, the Constitutional Court’s grounds for finding a violation in Esra Sarac Arslan case are not related to the examination of the authenticity and reliability of the Bylock servers’ data. What TCC requires is a superficial examination of whether the HTS records and CGNAT records are compatible. And the local court most likely would send the HTS and CGNAT records of the applicant to a police officer who would not be an expert; the police officer would say that the data were compatible and the applicant would be given the same sentence based on this report.

The Constitutional Court will never find a violation in relation to complaints that the digital copy of the Bylock servers’ data has been denied to defendants and that it has never been examined. This is because, the Constitutional Court has already found that (Turkish Intelligence Agency) MİT’s seizure and processing of Bylock servers’ data did not constitute a breach of law, despite the fact that it was not a law enforcement agency and it did obtain this data without judicial oversight. Moreover, the Constitutional Court is also aware that if an expert examination is conducted on Bylock servers’ data, this new report will most likely find that “the structure of it was corrupted”, as the expert panel commissioned by the Ankara Chief Public Prosecutor’s Office had already found [3]. However, such a report would dash all the arguments of the Constitutional Court in its Ferhat Kara and Adnan Şen judgements which found Bylock servers’ data was lawful evidence to pieces. For this reason, in order to save face, the Constitutional Court is passing such ostensible violation rulings which would have no effect on the merits of the case. The purpose of this violation judgment is to ensure that the data obtained by the MİT is made use of. However, it does not question the method and lawfulness of the acquisition/seizure of this data.

Yusuf Çoban Judgment of Constitutional Court

Background of the case

The Applicant Yusuf Coban who was convicted of membership in an armed terrorist organization solely on grounds of Bylock evidence had admitted that

“I used a programme called ByLock. This situation developed as follows; I went to Diyarbakır on a day off in July-August 2014 for sightseeing, and on the way back, a male person sat next to me on the minibus back to Diyarbakır. He said that his name was [Ö.] and that he worked as a classroom teacher in a village in Mardin and that he was from Afyon, I am already from Isparta and I trusted the person there because he was from a town close to my hometown. When we got off the minibus when we arrived in Mardin, we exchanged phone numbers and left. … It was around mid-August 2014, I saw [Ö.] walking in the bazaar again. Then we talked, and we decided to go somewhere and have tea. We went to [B.İ.] patisserie. There he told me “I’m calling you, your phone is always switched off”. I said, “My house is in the basement and the phone reception is not very good, so people who call me usually have this problem.” Then he showed me the programme called ByLock. He told me that if you want to use this programme, we can talk through this programme and that we will not have any communication problems even if your phone does not get a signal or the internet is very poor. … While we were sitting there, we downloaded this programme called [ByLock] from Google play store to my SAMSUNG Galaxy ICE brand phone.” And Yusuf Coban added his only contact through Bylock was Ö, he did not correspond to anyone other than Ö.

The applicant later withdrew his statement (of admission) and asked the trial court to collect evidence to determine whether he had actually downloaded/used Bylock and also asked for an expert examination to find the material truth. The trial court, however, said: “Although in his defense before our court he stated that the line numbered [0507 …] belonged to him, that he used this line between 2010 and 2015, but that he did not use the program called ByLock, considering the facts that the ByLock enquiry detection report stating that the defendant used the ByLock program with the line numbered [0507 …], … and the defendant’s statements … at the police station and the defendant’s statement  at Mardin 1st Criminal Judge of Peace on 21/04/2017 that he had used this program, his defense denying the usage of the program was not taken into consideration … it was decided to sentence the defendant in accordance with paragraph 314/2 of the TPC.”

Subsequently,  the 16th Criminal Chamber of the Court of Cassation rejected the applicant’s appeal and upheld the judgement by stating:  “The fact that the verdict was rendered without waiting for the detailed ByLock detection and assessment report on the defendant being a ByLock user, the defense (acknowledgement/admittance) of the defendant and the other evidence in the file were sufficient for the conviction of the offence and (deficiencies) were not found to be effective on the result.”

TCC  reached a conclusion almost the exact opposite of its Esra Saraç Arslan judgment

Having found a violation of the right to a fair trial in the Esra Saraç Arslan judgment due to the failure to observe the principle of equality of arms, the Constitutional Court found the exact same complaint of Yusuf Çoban inadmissible only a few months later. What is more interesting is both judgments were delivered by the same justices and the same reporter judge.

Yusuf Çoban judgment was in absolute contradiction of the points TCC emphasized in its judgment of Esra Saraç. These points are namely that it does not approach the use of Bylock categorically, that mere usage of Bylock should not be the reason for conviction, and that whether the application had been used for the purposes of the Organisation should be sought.

In short, unlike the Esra Saraç Arslan judgment which had the same content and nature, the Constitutional Court concluded that the applicant’s complaints were related to the evaluation of the evidence and the interpretation of the rules of law, that the reasoning that the court of first instance did not constitute an obvious error of appreciation or clear arbitrariness and that these allegations were as such which should be dealt with by “ordinary courts”.

Unlike the Esra Saraç Arslan judgement, the Yusuf Çoban judgment was passed by a majority of votes. The points made by the dissenter Deputy President of the Court Hasan Tahsin Gökcan reflect how the Constitutional Court has brazenly trampled on the principle of legal security.

Deputy President of the Court, Mr Gökcan: This use of ByLock data, unfortunately, constitutes the categorical approach

The Constitutional Court’s judgement in Esra Saraç Arslan is a precedent (for this case). … It was not correct to depart from this precedent in the application under review.

… of course, (one’s) admission (of allegations against him/her) has evidential value. However, taking the defendant’s admission as a basis for conviction by adding the things he did not say is contrary to both the principle of the defendant benefits from the doubt and the principle of indivisibility of admission... These principles are closely linked to the principle of fair trial and the principle of equality of arms. For this reason, making a decision … without first having the “Bylock Detection and Evaluation Report”, may damage the fairness of the trial.

… … the applicant’s request for a technical examination of the digital data was dismissed by pointing out his partial admission, and the decision was reached without first bringing the detection and evaluation report into the file or giving the applicant the opportunity to put forward his defence and counter-arguments. As stated in another decision of our Court, preventing the submission of evidence that can only be obtained with the help of the State (court-administration) violates the principles of equality of arms and adversarial trial (B. No: 2020/2395, par. 18).

Briefly, without considering the content of the applicant’s admission, … the dismissal of the applicant’s request for an expert examination (and) convicting the applicant without waiting for the arrival of the ByLock detection and evaluation report that contains server-originated information although it was possible … resulted in the applicant not being given the opportunity to prove and challenge the court’s assumption. On the other hand, it should be remembered that there is no other evidence, witness testimony, etc. in the file against the applicant that he is a member of an illegal organisation. This use of ByLock data unfortunately reflects the categorical approach. In this case, the criminal proceedings were completed entirely with the court’s prejudiced approach and assumptions, without allowing for the discussion of evidence and the presentation of counter-arguments. … The right of defence regarding the evidential quality of the data in the file, which consists of the HTS report and the interview transcript, may only be possible by obtaining an expert report, as seen in precedent judicial decisions. Unfortunately, the applicant’s request in this respect was dismissed and the applicant was not given the opportunity to have the document, which is the main evidence, submitted into the file or provide a defence against the said document. Such a trial is contrary to the right of the accused to be provided with adequate facilities for defence, the principles of adversarial proceedings and equality of arms, and thus the fairness of the proceedings has been damaged. His right to a fair trial has been violated.


The Turkish government argues before the Committee of Ministers of the Council of Europe that Turkey has complied with the ECtHR’s judgments (Tekin Akgün, Taner Kilic and other judgments) related to proceedings against alleged Bylock users.

Turkey further states “… the Constitutional Court examined the evidentiary nature of the Bylock application … in its decision of Aydın Yavuz and others no.2016/22169), and made significant findings concerning the organisational aspect of this application. … In its decision of Ferhat Kara ([Plenary], no.2018/15231, 4/6/2020), the Constitutional Court addressed the evidentiary nature of the Bylock application in the context of the right to a fair trial and conducted a multi-faceted examination in respect of this application from its technical features to its organisational aspect.”[3]

However, as underlined above and particularly in the mentioned dissenting opinion, the TCC’s approach to Bylock is categorical, in other words, it gives a green light to the imprisonment of every person who downloaded Bylock regardless of the elements of the alleged offence (membership in an armed terrorist organization).

Also, as we explained the TCC’s judgments with regard to the Bylock cases contradict each other and its jurisprudence is far from ensuring legal certainty and foreseeability.

There are only 2 months and 10 days between these two diametrically opposite judgements, written by the same rapporteur and issued by the same General Assembly of the Constitutional Court. This contradictory approach of the Constitutional Court, which has now become almost the norm, begs the question as to how long the ECtHR will insist on seeing the Constitutional Court as an effective domestic remedy, and, in that sense, the Yalçınkaya judgement, which is expected to be announced later this year, will present a good opportunity to find out.



[3] Gulen Movement which is an organization proscribed by the Turkish government and called FETO-PDY.

[4] This is a report extracted from an online module created for police where the police officers can enquire whether a person is a Bylock user, data related to the respective Bylock user account.



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