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Conviction Based on Secret Witness Statement - Turkish and ECHR Approach

14 Mart 2026 Evidence Law and Precedent Decisions 6 dk okuma 37 görüntülenme

Confidential (anonymous) witness; A witness whose identity information is kept confidential due to life safety or professional/family circumstances. CMK Article 58 and special laws (Anti-Terror Law No. 3713) include this institution. However, convictions based on secret witness statements lead to serious debates in the context of the right to a fair trial, as they limit the defense's right to cross-examination.

Reminder: For informational purposes only; Evaluation of the concrete file depends on the judge's discretion.

CMK article 58 - Protection of Witness

"If revealing the identities of the people who will be heard as witnesses would pose a serious danger to themselves or their relatives", necessary precautions are taken to keep their identities secret. Instead of the witness's obligation to be present at the hearing, the witness may be made to testify by other methods (e.g. by changing audio and video).

Witness Protection Law No. 5726

It prescribes comprehensive protection measures for the life safety and social security of the witness: identity change, relocation, physical protection, identity concealment.

Anti-Terror Law No. 3713

In terrorist crimes, secret testimony is more widely used.

Right to Fair Trial and Secret Witness Debate

Constitution art.36 and ECHR art.6/3-d; It grants the defendant the right to "examine or have interrogated witnesses." The practice of secret witness naturally restricts this right. For this reason, the European Court of Human Rights (ECHR) has developed strict criteria for convictions based on confidential witness statements.

The Criterion Developed by the ECHR - "Single and Decisive Evidence" Test

The ECHR, in its Al-Khawaja and Tahery v. United Kingdom decision (Grand Chamber), developed a three-stage test for convictions based on witness statements heard in secret/in their absence:

  • Is there a valid reason? There must be a sufficient and reasonable reason for the witness to be kept secret or not present at the hearing.
  • Is the witness statement the "sole or decisive evidence"? Is the conviction based solely or largely on the confidential witness statement?
  • Are "compensatory guarantees" provided for the defense? Have procedural guarantees (written questions, meticulous evaluation of the court, additional evidence) been provided to compensate for the defendant's violation of rights?
  • Three conditions are evaluated together; If the conviction is based solely on the confidential witness statement and compensatory guarantees are insufficient, a violation of ECHR Article 6 is determined.

    Approach of the Turkish Judiciary

    The Supreme Court Criminal General Assembly and the relevant Criminal Chambers adopted the ECHR jurisprudence; The following principles are established for convictions based on confidential witness statements:

    • Secret witness statement on its own is not considered sufficient for conviction; It must be supported by supporting evidence.
    • A valid and concrete reason for keeping the witness confidential must be stated in the file.
    • The defense should be given the opportunity to ask and answer written questions to the confidential witness.
    • In the justification of the court decision, it should be explained how the confidential witness statement was evaluated and what additional evidence it supported.
    • The right to object to the confidential witness statement should not be restricted.

    Precedent Decisions (Reference)

    • ECHR — Al-Khawaja and Tahery v. United Kingdom (Grand Chamber, 2011):The basis of the three-stage test; It has set forth the principles of evaluation of witness statements heard in secret/in their absence.
    • ECHR - Decisions Against Turkey: The ECHR found a violation of the right to a fair trial against Turkey in cases where convictions based on secret witness statements were not supported by additional evidence or where compensatory guarantees were insufficient.
    • Criminal General Assembly of the Supreme Court of Appeals: There are principled decisions stating that the statement of a secret witness cannot be accepted as the sole and decisive evidence and that it must be supported by strengthening evidence. The fact that the conviction was based solely on the statement of a secret witness was seen as a reason for reversal.
    • Supreme Court of Appeals 16th Criminal Chamber - Secret Witness in Terrorism Cases: The compatibility of secret witness statements with other concrete evidence in the file (HTS, bank record, physical witness, digital trace) is carefully evaluated; Convictions based on abstract statements may be subject to reversal.
    • Constitutional Court - Individual Application: The Constitutional Court has made various decisions finding violations of the right to a fair trial in convictions based on secret witness statements, for reasons such as restricting the defense's opportunity to object and interrogate, and insufficient justification.

    Compensatory Safeguards — What Should Be Done in Practice?

    In cases where confidential witness statements are used as a basis for conviction, the following assurances are expected to be provided for the defense:

    • Giving the defendant or his defense counsel the opportunity to ask written questions to the witness
    • The court's evaluation of the confidential witness statement by comparing it with additional evidence
    • Disclosure of the witness's general information and observations that form the basis of his testimony to the defense (non-identity information)
    • Evaluating the credibility of the witness in the justification of the court decision
    • Providing the opportunity to resolve the conflict against the defendant

    Defense Strategy

  • Question the justification for confidentiality: Is there a concrete danger in keeping the witness confidential? Abstract justifications should not be sufficient.
  • Prepare your written questions meticulously: Ask questions that question the reliability of the witness, the relationship of hostility/interest, the sources and details of the statement.
  • Highlight the inadequacy of additional evidence: Show that the conviction was based solely on confidential witness testimony; Remind us of the "single and decisive evidence" test.
  • Analyze the justification for the decision: Insufficient or contradictory justification may be grounds for reversal.
  • Reserve the right to individual application: The Constitutional Court and, if necessary, the ECHR are open; In case of detection of a violation of rights, retrial is possible.
  • Conclusion

    The practice of secret witness is an institution accepted in Turkish and international law; However, since it limits the defense's right to cross-examination, it is not considered sufficient for conviction on its own. The "sole and decisive evidence" test and the "compensatory guarantees" approach developed by the ECHR have been adopted by both the Supreme Court and the Constitutional Court. In order for the conviction to be legally sustainable, the secret witness statement must be supported by supporting evidence. Since the fact pattern of each file is different, the outcome is specific to the file and is at the judge's discretion.

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