1. Drug Offense: General Legal Framework and the Requirement of CMK Article 134
According to Supreme Court decisions, in the crime of drug trafficking, it is mandatory to comply with the procedures specified in Article 134 of the Criminal Procedure Code (CMK) numbered 5271 for the examination of the suspect’s mobile phone and for the messages therein (WhatsApp, SMS, etc.) to be accepted as evidence. In this context, for a mobile phone to be examined and data to be recorded, there must absolutely be a judge’s decision or, in cases where delay would be prejudicial, a written order from the Public Prosecutor. Examinations conducted with a prosecutor’s order must also be submitted for a judge’s approval within twenty-four hours (Supreme Court 10th CD-2022/10246, 2023/15758K).
2. Legal Nature of Examinations Conducted with Consent
According to the established jurisprudence of the 10th Criminal Chamber of the Court of Cassation, even if the suspect gives consent, phone examinations conducted by law enforcement without a judge’s decision or prosecutor’s order constitute unlawfully obtained evidence. The suspect’s voluntary handover of their phone or disclosure of its password does not replace the procedure stipulated in Article 134 of the Code of Criminal Procedure. Messages obtained in this manner and witness statements derived from these messages are considered “evidence obtained unlawfully” and cannot form the basis of a judgment (Court of Cassation 10th Criminal Chamber-2023/15758, 2020/12500K, 2022/15892K). However, although some decisions have presented different justifications for examinations conducted with the suspect’s consent to be considered legal evidence, the general tendency is that such evidence cannot form the basis of a judgment (Court of Cassation 10th Criminal Chamber-2020/12500).
3. Evidential Value of Messages and HTS Records
Properly obtained phone examination records, WhatsApp correspondences, SMS records, and HTS (communication traffic) data are considered significant evidence for establishing the commission of a crime in drug offenses:
Proof of the Crime: Message contents related to the procurement, negotiation, or delivery of narcotic substances between suspects are considered one of the primary bases for determining the nature of the crime and for a conviction (Court of Cassation 8th Criminal Chamber-2024/1931, 2024/2263, 2024/4705).
HTS and Base Station Information: HTS records and base station signals indicating the defendants’ communication with each other and their presence in the same area at the time of the incident, when supported by other material evidence, ensure that the crime is established (Court of Cassation 10th Criminal Chamber – 2023/633K, 2024/1412K).
Interception of Communication (Article 135 of the CPC): Telephone wiretaps (tapes) and SMS interceptions made with a judge’s decision are considered a legitimate interference with the freedom of communication and legally valid evidence by the Constitutional Court and the Court of Cassation (Constitutional Court – 3/2/2016, Court of Cassation 8th Criminal Chamber – 2024/821).
4. Verification of Evidence and Technical Examination
For telephone records to be used as evidence, certain technical conditions must be met:
Voice Analysis: If the defendant claims that the voice in the telephone conversations does not belong to them, it is mandatory to take voice samples and conduct a voice analysis by the Forensic Medicine Institute or expert organizations (Court of Cassation 10th Criminal Chamber – 2023/3928K, 2018/783
Expert Report: To determine the content of messages and phone calls, an expert report must be obtained, and defenses must be compared with these records (Court of Cassation 10th Criminal Chamber – 2020/2435).
Support with Material Evidence: Mere message records or phone conversations, especially if their content is ambiguous or not supported by material findings (e.g., seized narcotics, precision scales, etc.), may not be considered sufficient for conviction on their own (Supreme Court of Appeals, Criminal General Assembly-2020/415, Sakarya Regional Court of Appeals-2019/2440).
5. Conviction and Acquittal Criteria
Reason for Acquittal: An acquittal decision is rendered if the messages are old, do not contain concrete and definitive statements regarding drug trafficking, or were obtained through illegal methods (Sakarya Regional Court of Appeals-2019/2440, Supreme Court of Appeals 8th Criminal Chamber-2024/2686).
Reason for Conviction: A conviction decision is upheld if the message contents are contrary to the ordinary course of life (e.g., coded conversations made late at night and linked to trafficking), align with drug seizures, and are supported by witness statements (Supreme Court of Appeals 8th Criminal Chamber-2024/3047, 2024/4180).
6. Secondary Source Evaluation
In the Supreme Court of Appeals 10th Criminal Chamber’s decision numbered 2022/13796, presented as a secondary source, it was emphasized that communication interception records were used to prove a unity of thought and action among the defendants, but the lack of voice analysis for conversations denied by the defendant was considered an incomplete investigation. This source confirms that phone records are generally accepted but technical verification is mandatory.
In conclusion; in drug offenses, phone examinations and messages are considered evidence, provided they are obtained with a judge’s decision or a prosecutor’s order in accordance with Article 134 of the CMK. These legally obtained data are taken as the basis for judgment to the extent that they are supported by material findings.
Why Do Phone Examinations and Message Evidence in Drug Offenses Require Expert Legal Support?
In drug offenses, the examination of mobile phones and the use of WhatsApp and SMS messages as evidence is a highly technical and procedure-sensitive area, strictly tied to Articles 134 and 135 of the CMK. Examinations conducted without a judge’s decision can be considered unlawful evidence, even with the defendant’s consent; conviction decisions based on such evidence are frequently overturned by the Supreme Court.
The most common errors in practice are; the prosecutor’s order not being submitted for judge’s approval, the phone image not being acquired in accordance with proper procedure, message contents not being verified by an expert report, and HTS–base station records not being supported by material evidence. These shortcomings can lead to severe consequences for the defendant and, if an effective defense is not mounted, can result in irrecoverable loss of rights.
Digital evidence plays a decisive role, especially in drug investigations conducted in regions such as Istanbul, Tuzla, Pendik, Kartal, Maltepe, Gebze, and Çayırova. Therefore, from the outset of the process, the legality of phone examinations, the interpretation of message contents, requests for voice analysis, and the assertion of evidentiary prohibitions all require specialized expertise.
At this point, 2M Law Firm, based in Tuzla, Istanbul, with its approach that is well-versed in the precedents of the Supreme Court and the Constitutional Court regarding phone examinations and communication evidence in drug offenses, provides effective, strategic, and results-oriented legal support to defendants and their counsel during the investigation and prosecution phases. Expert criminal defense lawyer support is vitally important for the elimination of unlawfully obtained evidence and the protection of the right to a fair trial.
