One of the frequently used evidence in criminal investigations and prosecutions is HTS (Historical Traffic Statistics) records. HTS; It contains information about the calls made by a phone number within a certain date range, the SMS it sent and the base station it connected to. These records are used to show where the defendant was or with whom he or she communicated at the time of the crime. In this article, the evidentiary value of HTS and the approach of the Supreme Court are discussed.
Reminder: For informational purposes only. The decision to be made depends on the circumstances of the concrete case and the judge's discretion.
What Do HTS Records Show?
- Calls made from/to phone number (outgoing and incoming)
- Date, time and duration of the meeting
- Other party phone number
- Base station (BTS) information and cell ID to which the phone is connected during the call/SMS
- SMS sending and receiving records
- Mobile data connection times (limited)
Important: HTS does not include the content of the conversations; It only contains metadata. The content of the conversation requires detection of communication or an interception decision (CMK Article 135).
Legal Basis of HTS
Access to HTS records is considered as "detection of communication" within the scope of CMK art.135. Access requires judge's decision; In cases where delay is harmful, a written order from the public prosecutor is obtained and submitted to the judge for approval within 24 hours. Access is only possible in terms of catalogue crimes listed in the law (CMK art. 135/8).
HTS records obtained illegally (e.g. without a judge's decision, other than a catalog crime, an irregular request) cannot be used as evidence (Constitution Art. 38/6, CMK Art. 206/2-a, Art. 217/2).
Limitations of HTS — Why Is It Not Enough on Its Own?
1) The Owner of the Phone and the User May Not Be the Same
Phone lines can be shared among family members, employees, loved ones or others. The line owner (subscriber) and the person actually using the phone at the time of the crime may not always be the same.
2) Base Station Covers a Wide Area
A base station can cover an area of approximately 500 meters - 2 km in urban areas and 5-15 km in rural areas. Therefore, HTS does not indicate that the defendant was "at the exact scene of the crime" but rather that he "may have been tied up in a possible area."
3) Fake Line and Line Theft (SIM Swap)
In cases where lines are opened with someone else's credentials or SIM card copying (sim swap) attacks carried out by deceiving operator employees, the real owner of the line may be unaware of the criminal act.
4) Shows Only the Conversation, Not Its Content
The fact that two people met does not prove that the meeting was conducted to commit a crime. It may have been done for legitimate reasons such as kinship, friendship, business relationship.
Approach of the Supreme Court
The Supreme Court Criminal General Assembly and the relevant Criminal Chambers firmly apply the following principles when evaluating HTS records as evidence:
- HTS records alone are not considered sufficient for conviction; It should be evaluated together with other supporting evidence
- It must be demonstrated with additional evidence that the defendant personally used the line on the date of the crime.
- Since the base station signal covers a wide area, "being close to the crime scene" alone cannot be considered evidence of perpetration.
- Merely having an interview does not constitute evidence of participation in a crime or membership in an organization.
- HTS analysis should be done through expert expert; In case of contradiction, the right to object should be granted.
Precedent Decisions (Reference)
The following principles reflect the established practice of the Supreme Court. The decision texts can be accessed from the Supreme Court Decision Search or via UYAP.
- Criminal General Assembly of the Supreme Court - Organization Membership and HTS: It has been jurisprudence that just having a conversation with certain numbers is not considered sufficient for organization membership unless it is supported by concrete activity.
- Supreme Court of Appeals 6th Criminal Chamber - Base Station in Theft/Plunder Cases: It was not considered sufficient for the defendant to signal the base station close to the scene of the crime during the crime hours; additional evidence such as eyewitnesses, seizures and camera recordings were examined.
- 16th Criminal Chamber of the Supreme Court of Appeals - HTS on Terrorism Accusations: The frequency of meetings with certain person(s) alone was not deemed sufficient to prove guilt; The existence of additional evidence such as the content of the meeting, joint action, and physical testimony was sought.
- Constitutional Court - Fair Trial: The Constitutional Court found a violation of the right to a fair trial in cases where defense objections to the HTS analysis were not adequately evaluated or contradictions in the expert report were ignored.
- ECHR - Respect for Private Life (ECHR Art. 8): Collection of communication metadata (HTS) is also an intervention in private life within the scope of ECHR Art. 8; Failure to comply with the legal basis, necessity and proportionality conditions is a reason for violation.
Unlawful HTS – Absolute Prohibition of Evidence
HTS records obtained in the following cases cannot be used in the trial:
- Things obtained without a judge's decision (CMK article 135)
- Those requested for a crime other than catalog crimes
- Those held after expiration
- Those taken by unauthorized authority
Constitution Article 38/6: "Findings obtained illegally cannot be accepted as evidence." The Supreme Court of Appeals and its Chambers strictly implement this principle.
Defense Strategy
Conclusion
HTS records are an important type of collateral evidence in criminal proceedings, but it is the established approach of the Supreme Court that it alone is not considered sufficient for conviction. The judge's conscientious opinion must be based on concrete, solid and unquestionable evidence; HTS records should be evaluated together with supporting evidence in this context. Since the fact pattern of each file is different, the result is specific to the file.