Seized, hacked, or leaked data: evidentiary boundaries in Turkish law

Alper Arslan
Arslan & Arslan Law Office, Istanbul
alper.arslan@arslanlaw.com.tr

The approach of the Turkish Constitution

Article 38(6) of the Constitution expressly provides that ‘findings obtained in violation of the law shall not be accepted as evidence.’

Accordingly, the prohibition of unlawfully obtained evidence is not merely a technical rule of proof; it is a constitutional safeguard designed to protect fundamental rights. This demonstrates that the matter cannot be approached solely through the lens of freedom of proof.
Indeed, the limits of proving material truth by means of evidence are defined by the requirement that evidence be obtained in a manner consistent with the law and with fundamental rights and freedoms, and that it be presented lawfully.

Unlawfully obtained evidence in criminal proceedings

The Turkish Criminal Procedure Code (CMK) reiterates the constitutional prohibition in a systematic manner. If evidence has been obtained in violation of the law, it must be rejected. The offence charged may be proved by any evidence lawfully obtained (Articles 206 and 217 CMK). In other words, unlawfully obtained evidence cannot form the basis of a judgment.

It is generally accepted that evidence obtained in situations such as unlawful search and seizure, digital examinations conducted without a judicial order, irregularities in interrogation procedures, or unlawful interception of communications lacks evidentiary value.

A defining feature of criminal proceedings is that even the objective of establishing the material truth does not legitimise unlawfulness. Evidence may be compelling; yet if it has been obtained unlawfully, it cannot be relied upon.
In particular, with regard to digital material, it is critically important that evidence be obtained lawfully and that its integrity be preserved. Because digital data can easily be copied, altered, or manipulated, Turkish judicial practice places particular emphasis on the transparency and verifiability of the acquisition and examination process. Factors such as the lawful conduct of search and seizure measures, the preservation of original data through exact copies, the maintenance of chain of custody records, and the preparation of a forensic examination report therefore play a decisive role in assessing the reliability and evidential weight of digital evidence.

For instance, there are decisions of the Court of Appeals in which digital findings were deemed unlawful, and convictions were overturned, where a phone examination was not conducted in accordance with procedure or where the scope of the seizure order had been exceeded.

By contrast, where lawful seizure, technical examination, and supporting material such as bank records, camera footage, or data reports are assessed together, digital data may form the backbone of a conviction.

One of the most controversial issues in practice concerns data alleged to have been obtained unlawfully by private individuals. Where no law-enforcement measure is involved, the same degree of strictness is not always seen.

Case law of the Court of Appeals indicates that recordings made in suddenly developing situations, where a person has no other possibility of obtaining evidence concerning a crime being committed against him or her, may be regarded as lawful.

That exception, however, is interpreted narrowly: there must be a suddenly developing and ongoing offence, there must be no alternative means of obtaining evidence, and there must be no possibility, or no practical possibility, of applying to the competent authorities.

Planned, prolonged, or provoked recordings are not considered to fall within this exception.

The approach in civil litigation

Although Article 38 of the Constitution is placed under the section on criminal matters, Turkish case law has accepted that the prohibition of unlawfully obtained evidence also applies in civil proceedings. Article 189(2) of the Turkish Code of Civil Procedure (HMK) has made this approach an express rule of positive law.

Article 189(2) HMK provides:

‘Evidence obtained unlawfully shall not be taken into consideration by the court.’

This provision confirms that evidence relied upon in judicial proceedings must be obtained lawfully and that unlawfully obtained evidence has no evidential force, thereby defining the limits of the right to prove one’s case.

Even if no objection based on unlawfulness is raised by a party, the court is under a duty to consider ex officio the manner in which the evidence was obtained. Where it is established that evidence has been obtained unlawfully, the court must rule that it is inadmissible and must not take it into account, even absent any objection by the opposing party.

A decision of the Court of Appeals dated 26 November 2014 (E.2013/4-1183, K.2014/960) drew an important distinction in relation to digital evidence:

Obtaining evidence irregularly and creating evidence irregularly are two different matters. While evidence obtained irregularly may be evaluated according to the particular features of the case, evidence irregularly created cannot be accepted under any circumstances.

This distinction is of central importance in debates concerning hacked and leaked data.

Irregularly created evidence

If evidence has been produced through a fictional scenario or by way of manipulation—for example, if a planned scenario is set up in order to induce the opposing party into making certain statements and those statements are secretly recorded—what exists is no longer the identification of a pre-existing reality, but the construction of evidence.

In such a case, whether the content of the evidence is accurate or materially true becomes secondary; the method itself is unlawful.
This approach is particularly significant in the context of digital manipulation risks. Edited recordings, message chains taken out of context, or provoked conversations may technically constitute ‘data,’ but they lack legal legitimacy. The line drawn by the high court is clear: fabricated evidence cannot be legitimised by the court.

Irregularly obtained evidence

With regard to irregularly obtained evidence, decisions of the Court of Appeals refer to evaluation ‘according to the specific circumstances of the case.’ At first sight, this may seem to suggest a balancing exercise. Yet in practice, following Article 189(2) HMK, the boundary is fairly strict: once unlawfulness is established, the evidence cannot be taken into account in proving a fact. 

Decisions of the Court of Appeals particularly concern disputes involving audio recordings, private correspondence between spouses, documents taken by an employee from the employer’s system, and internal corporate email traffic.

The use of records obtained in connection with violations of personality rights, privacy, or data rights carries high risk in Turkish judicial practice. In cases involving audio recordings, secret video footage, or unauthorised access to emails, lawfulness is generally not accepted save in exceptional circumstances.

On the other hand, for evidence to qualify as unlawfully obtained, the data must have been obtained by means of unauthorised access, password cracking, unauthorised system intrusion, covert interference, or an interference with an area protected by fundamental rights. By contrast, where a party to a communication or its legitimate recipient discloses message content or submits it to the court, that alone cannot be characterised as unlawful ‘acquisition.’ Unlawfulness stems not from the disclosure of the content, but from the method by which access to the content was obtained. For that reason, where messages are shared by the parties to the communication or by their recipients, and there has been no unauthorised or covert interference, such material may in many cases not be characterised as unlawfully obtained evidence.

In civil proceedings, reference is also sometimes made to the fairness of the proceedings as a whole in relation to unlawfully obtained evidence. Turkish Court of Appeals does not approach the issue solely in terms of a binary contrast between prohibition and permissibility. It also examines the impact of unlawfully obtained evidence on the fairness of the proceedings.

That inquiry proceeds in two stages: first, it is assessed whether the method of obtaining the evidence constitutes an interference with fundamental rights; second, it is determined whether the evidence was the sole or decisive basis of the judgment.

Where unlawfully obtained evidence forms the sole or decisive basis of the decision, the conclusion has been reached that the proceedings, taken as a whole, were not fair.

Freedom of evidence in arbitration and the limit of public policy

Although the assessment of evidence in arbitration may appear more flexible, two principal limits remain: Turkish public policy, particularly at the annulment and enforcement stages, and the principles of equality of arms and due process.

Where an arbitral award relies on unlawfully obtained data, it may be exposed to the risk of annulment or non-enforcement, particularly on grounds of public policy or the right to a fair trial.
Accordingly, freedom of evidence in arbitration does not mean that unlawfulness can be disregarded. Particularly where hacked or leaked data is involved, reliance on such material may offer a short-term procedural advantage but may create risks for the enforceability of the award.

Neither the International Arbitration Law (Law No. 4686) nor the arbitration provisions of the Turkish Code of Civil Procedure (HMK) contain an express rule on unlawfully obtained evidence. Arbitral tribunals enjoy a measure of discretion within the framework of party equality, fair trial guarantees, and procedural economy.

That said, such freedom is not unlimited. A breach of public policy may constitute a ground for setting aside an award. Therefore, if reliance on unlawfully obtained evidence results in a violation of fundamental rights or of the right of defence, the award may, depending on the circumstances, be vulnerable to annulment, or enforcement may be refused.

In practice, particularly in international arbitration, it is often seen that greater weight is placed on the reliability of the evidence than on its source. Nevertheless, at the annulment or enforcement stage, the public policy filter may still come into play.

Conclusion

In many legal systems, particularly in civil proceedings, unlawfully obtained evidence is not automatically excluded. Turkish law, however, adopts a stricter framework in relation to unlawfully obtained evidence.

Under Turkish law, ‘seized,’ ‘hacked,’ or ‘leaked’ data is not categorically accepted or rejected merely by virtue of its label. The real questions are these:

• Was the data fabricated through a constructed scenario?
• Was it obtained through unauthorised or otherwise unlawful interference?
• Does the method by which it was obtained infringe fundamental rights?

The accuracy of the evidence is not sufficient on its own. The pursuit of material truth does not legitimise an unlawful method.

That said, practice suggests that Turkish judicial reasoning draws a de facto distinction between, on the one hand, infringements involving fundamental rights, particularly in criminal proceedings, and, on the other hand, infringements arising in disputes rooted more heavily in contractual relationships, as is often the case in civil litigation or arbitration.

Where the method of obtaining evidence constitutes an interference with constitutional guarantees such as privacy of private life or secrecy of communications, the courts tend to apply the prohibition of unlawfully obtained evidence more strictly. By contrast, in disputes arising out of commercial and contractual relationships, courts often focus on how the information was accessed and may interpret the prohibition more narrowly when the information is disclosed by a party to the communication or its legitimate recipient. This does not point to a normative distinction, but rather to a de facto evaluative practice emerging from judicial decision-making.

In the digital age, the fate of a dispute may be shaped not only by the content of the evidence, but also by the manner in which it was obtained. For that reason, from the perspective of Turkish law, the debate is not merely about proving what is true, but about proving it through lawful means.

In Turkish law, the method by which evidence is obtained may be as decisive as, and often even more decisive than, the content of the evidence itself.