Unlawfully obtained evidence in Turkish criminal proceedings

Information that helps explain an event is not necessarily admissible in criminal proceedings. An object found during a search, an extracted message, a police statement or a privately made audio recording may be relevant to the facts. Its legal basis, scope and acquisition method must nevertheless be examined. Criminal procedure does not pursue truth at any cost: it must do so within the rule of law.

An unlawful-evidence objection is therefore more than a technical procedural point. It can concern search authorisation, digital integrity, voluntary statements or defence access to raw data. A sound assessment separately identifies the evidence, how it was obtained, how it was contested and the weight it carried in the judgment.

This article outlines how such an objection can be developed in a criminal case. Authorisations, records, digital methods, interview conditions and other evidence differ between files. The discussion is not a case-specific legal opinion.

The statutory boundary

Article 38(6) of the Constitution prohibits admitting unlawfully obtained findings as evidence. The Code of Criminal Procedure (CMK) gives effect to that choice at three stages: Article 206(2)(a) rejects requests to introduce unlawful evidence; Article 217(2) requires lawful evidence to prove an offence; and Article 230(1)(b) requires unlawfully obtained material to be identified separately and expressly in the reasoned judgment.

Courts cannot simply say that evidence is important. They must address specific acquisition objections, assess lawfulness and explain their conclusion. If evidence is excluded, the sufficiency of the remaining lawful material requires separate assessment. Excluding one item does not automatically mean acquittal; the presence of other records does not necessarily remove the disputed item’s decisive influence either.

Four similar-looking questions concern different issues

Four matters are often confused in unlawful-evidence arguments:

1. Was acquisition lawful? Were the necessary decision, order, degree of suspicion and safeguards present for the search, seizure, interception, interview or digital examination?

2. Does the record genuinely show what is claimed? Has its source, digital authenticity, speaker’s identity or continuity of footage been verified?

3. Could the defence challenge it effectively? Could it comment on the records, expert report, forensic image or relevant raw data?

4. What weight did it carry? Did the conviction principally depend on it, or was there independent, lawful corroboration?

These concern acquisition law, reliability and attribution, adversarial proceedings and equality of arms, and proof and reasons respectively. Several may coexist. A phone conversation might be obtained through disputed authority, submitted only as selected screenshots and then become the main basis for conviction. Saying that ‘the phone was examined’ does not enable meaningful legal scrutiny.

Does every procedural error have the same consequence?

A departure from formal requirements and a breach removing a fundamental safeguard cannot be dismissed alike. The rule’s purpose, protected right and connection to the evidence must be explained. The Sixteenth Criminal Chamber decisions below discuss formal deficiencies but do not treat unlawful interception’s interference with communication rights as trivial. They do not confer a general discretion to disregard constitutional and CMK exclusions.

Calling an error minor does not make every omission harmless. Failure to observe a safeguard securing independent scrutiny and later verification of a search may concern more than the form of a record. If the timing and method of digital copying are unknown, integrity and effective defence objections may be affected, not just paperwork. The nature of the breach must be explained through the actual chain of operations.

For search and seizure, begin with the authorisation

Review starts with the legal authority, before the search record. Was there a judge’s decision or, where permitted, a competent authority’s written order? Whom and which premises did it cover, on what suspicion, and was it executed within its time and subject limits? These answers matter more than the label attached to the search.

Homes, workplaces, vehicles, persons and possessions are not governed identically. Investigative and preventive searches also have different purposes. Preventive powers are not an unrestricted alternative for collecting evidence in a specific criminal investigation. Where special conditions for an offence in progress, urgency or seizure apply, contemporaneous records must establish them. General explanations added later cannot replace authority at the time.

Execution requires separate scrutiny. Exceeding scope, omitting persons whose presence is required or uncertainty about who found an object and where can affect lawfulness and reliability. In Mehmet Cengiz and Rıdvan Cengiz (application no. 2019/21704, 20 September 2023, §§ 91–97), the Constitutional Court found an unfair-trial violation from decisive use of evidence obtained without required search witnesses and failure to address objections. It expressly stated that this did not itself entail acquittal (§ 103).

Statements and questioning require free will

Article 148 of the CMK requires a suspect’s or accused person’s statement to be voluntary. Methods impairing free will, including ill-treatment, torture, administering drugs, exhaustion, deception, coercion, threats and unlawful promises of benefit, are prohibited. Statements obtained through prohibited methods cannot be used as evidence even with consent.

A record saying ‘the statement was given voluntarily’ is not sufficient. Arrest time, police-custody conditions, access to counsel, medical reports, interview duration, rest, questions and any later withdrawal must be considered together. Where pressure is alleged, both how and when it was raised and whether the authorities effectively investigated it matter.

The law also prevents a police statement taken without defence counsel from supporting a judgment unless confirmed before a judge or court. Presence in the file is distinct from use for conviction. Courts should explain which parts they consider reliable and usable, rather than merely list the contested statement alongside other evidence.

For digital evidence, the procedural history matters as well as the content

Phones, computers, external drives, cloud accounts and messaging applications increasingly supply evidence. Volume and ease of copying do not make digital records inherently reliable: they can be deleted, changed, removed from context or misattributed. Acquisition and examination must therefore be reviewable alongside the content.

First identify authority and scope: which device, suspected offence, examiner and decision? Were particular dates or data types specified? If all contents were accessed, how was that breadth connected to the case? An existing search decision does not automatically justify work beyond its limits.

Next comes integrity. Custody must be traceable from receipt and imaging through storage and transmission to the expert. Hashes help test later changes but do not resolve every issue; their stage, tool and dataset must be known. If only screenshots appear in a report, preceding and subsequent conversation, dates, times, sender–recipient matching and interpretations of deleted records may be impossible to check.

Third comes defence access. Selected screenshots may not permit effective challenge. The defence needs to assess lawfully accessible raw data, forensic copies, records and methods. In Yüksel Yalçınkaya v Türkiye (European Court of Human Rights, Grand Chamber, application no. 15669/20, 26 September 2023), the unexplained denial of access to applicant-related raw data, unanswered requests for independent examination and substantial reliability objections contributed to the fair-trial violation. The link leads to the Court’s official judgment announcement.

Finally examine attribution. Linking a number, username or device to a person does not prove that they performed every action on it. Where relevant, shared use, remote access, account security, backups and synchronisation must be addressed. Digital evidence gains strength from verified source, integrity, context and personal attribution, not a proliferation of technical terms.

Article 134: commencement position on 8 September 2026

Read together, operative parts A–C of the Constitutional Court’s judgment E.2023/128, K.2026/36 of 12 February 2026 annul Article 134 in full. The majority particularly addressed missing statutory safeguards for post-trial retention, deletion and limits on personal-data use. The ruling does not automatically invalidate every digital search or all earlier records.

The annulment takes effect on 25 February 2027, nine months after publication in the Official Gazette on 25 May 2026. Article 134 remained in force in the consolidated CMK text checked on 8 September 2026. Under its conditions, the text provides for judicial or urgent prosecutorial decisions, judicial approval of the latter and copying safeguards. Older judgments’ descriptions of authority must be separated from subsequent amendments; the rules applicable on the particular operation’s date must be identified.

Separate communication data from the measure used to obtain it

‘Telephone records’ are not one uniform legal category. Intercepted or recorded content, traffic data showing call times, cell-site information, subscriber records and messages stored on a device may have different sources. Authority, authorisation, scope and retention must be established for each.

Begin with the measure’s decision: which person or communication means, suspected offence and period? If legislation limits eligible offences, does the allegation qualify? Do extensions form an uninterrupted chain of authority? For incidentally obtained information, were conditions for recording and transferring it into the relevant investigation met? A transcript alone cannot answer these questions.

Traffic and cell-site data need careful interpretation. Use of a base station during a period does not invariably prove the owner’s precise location or conduct. Coverage, network load, actual user, time alignment and other variables may matter. Lawful acquisition does not make every inference scientifically sound; authority objections and objections to expert interpretation remain distinct.

Secrecy makes later judicial review more important. To the extent permitted by the file, the defence should be able to examine decisions and scope and contest the integrity and transcription of records used in judgment. Selected quotations require an explanation of why context was considered immaterial. If coded speech is alleged, courts must identify corroboration for their interpretation.

Review of lawfulness is not confined to the parties’ requests

Criminal courts must rely on lawfully obtained evidence discussed at the hearing. An apparent acquisition problem does not depend solely on whether the defence cites the correct article. Where decisions, records and reports indicate a serious breach, the court must assess it.

Timely, specific objections still help: courts can understand the requested investigation, obtain missing decisions and records, and ask experts relevant questions. Appellate courts can see whether the allegation was genuinely debated. Judicial scrutiny and the parties’ responsibility to substantiate claims complement one another.

Messages, screenshots and private recordings require separate assessment

A privately supplied WhatsApp conversation, social-media message, screenshot or audio file is not always usable simply because officials did not obtain it. Production and acquisition, interference with privacy or communications, integrity and submission circumstances must be examined. A desire to provide evidence does not justify every recording method.

Screenshots also raise completeness and attribution issues. A single frame may omit context; contact names can be changed, dates cropped and content edited. Original devices, exported conversations, server or provider records, admissions and independent data become important. Courts must examine who created the image, its source and completeness, not merely legibility.

The General Assembly decision below concerns an unauthorised ambient recording and reports derived from it. The Third Civil Chamber decision concerns social-media evidence in civil proceedings. Their subjects and procedural rules differ; neither substitutes for the other. This discussion is not permission or instructions to make covert recordings or access another person’s account.

Further evidence reached through unlawful evidence

A recurring question concerns information learned unlawfully but obtained through a separate later operation. ‘Fruit of the poisonous tree’ describes possible effects on derivative evidence; in Turkish criminal procedure it is not a single statutory formula automatically producing the same result in every case.

Establish the connection: did the later evidence come from a genuinely independent source, or does it repeat the unlawful operation? What authority and safeguards applied to the new procedure? Foreign-law exceptions are not automatically Turkish law. The Eleventh Criminal Chamber’s examination of invoices and derived reports illustrates why this relationship matters.

Identify what remains after exclusion

Requesting exclusion rarely completes the assessment. The remaining evidence must be identified and tested for proof beyond doubt. Independent witnesses, video, physical findings, financial activity or a statement before a judge may corroborate the event. If other material merely repeats the disputed record, apparent quantity is not independent proof.

This matters for reasons. A court may appear to reach the same result without quoting the challenged item while its factual narrative still depends on it. Examine which element of the offence it actually proves, not just whether the judgment expressly cites it.

The Constitutional Court does not reconsider admissibility as an ordinary appellate court. In Ferhat Gültek (application no. 2020/34051, 18 November 2025, §§ 61–80), it examined acquisition, reliability, challenge and use. No judicial finding or apparent unlawfulness, together with corroborating evidence, led to no violation. This does not authorise unconditional use of uncounselled police statements. Constitutional review remains distinct from trial courts’ duty to apply Article 148(4) of the CMK and other evidence rules.

Why must evidence be discussed at the hearing?

Article 217(1) permits a judge to rely only on evidence introduced and discussed before the court. Mere presence in the file is insufficient. Source, content and objections must be examined with the parties’ participation and a real opportunity for the defence to explain and challenge.

Reading a technical report’s conclusions may not amount to discussing the examination. What material and reproducible method underlie it? Why were alternatives excluded? Does raw data contradict the report? Unanswered questions may limit effective challenge despite formal introduction. Refusing further reports, expert testimony or a counter-expert opinion requires reasons addressing potentially decisive objections.

What should a reasoned judgment answer?

Article 230 requires accepted and rejected evidence to be identified, with unlawful material in the file separately and expressly shown. Copying a list of evidence does not discharge this duty.

For a potentially outcome-changing objection, the reasons should establish at least:

• Which evidence and operation are challenged?
• Which rule or safeguard is alleged to have been breached?
• Which documents and facts establish lawfulness or unlawfulness?
• If excluded, which independent evidence supports the judgment?
• If used, how were reliability and defence objections assessed?

An abstract phrase such as ‘the objection is unfounded in view of the file’ may not answer a decisive allegation. Courts need not respond to every word, but substantial arguments capable of changing the outcome cannot remain unanswered. Unlawful-evidence objections often qualify.

A sequence for examining the file

An objection is clearer when placed within the actual procedural sequence rather than supported only by detached quotations of legislation. A practical review can follow these steps:

1. Identify the precise evidence

Replace broad labels such as ‘phone records’ with the particular device, file, message sequence or object. Where possible, specify the record date, report number, page and appendix.

2. Reconstruct acquisition and custody

Arrange the initial tip or suspicion, decisions, orders, search, seizure, copying, storage, expert examination and submission chronologically. Gaps then become visible.

3. Compare authority with actual scope

Was the authorised operation the one performed? Were limits on place, person, device, dates or data exceeded? If urgency was asserted, was its specific basis recorded?

4. Separate reliability from attribution and acquisition

Lawful data may be misinterpreted or attributed to the wrong person. Apparently accurate content does not cure unlawful acquisition. These objections require separate headings.

5. Document defence access and challenge

Record, with dates, which documents or data were requested, how the requests were handled and whether expert questions or an independent examination were possible.

6. Explain the effect on judgment

Identify which offence element the disputed evidence supports in the indictment, prosecution’s final submissions and judgment. Reconstruct the proof without it, explaining why it is considered decisive.

When and how should the objection be raised?

Raise a specific, reviewable objection at the earliest practicable trial stage. That enables the court to address the breach, obtain documents and assess the evidence’s role. An objection recorded at the hearing also makes its scope clear for later review.

A submission should connect procedure to breach rather than list articles alone: identify the exceeded limit, reliance on an uncounselled statement or why an image’s integrity cannot be checked. Specify the remedy sought, such as exclusion, production of records, raw-data access, additional expert examination or reassessment of remaining evidence.

On appeal and cassation review, explain the trial court’s response and its effect. Article 289(1)(i) treats reliance on unlawfully obtained evidence as an absolute ground of unlawfulness. Nevertheless, identify the evidence, method and factual conclusion resting on it rather than merely cite the provision.

Common misconceptions

‘If it shows the truth, the method does not matter.’ Criminal procedure rejects that assumption. Accuracy and lawful acquisition are separate questions.

‘A search decision makes everything found usable.’ Scope, execution and the material’s connection to the suspicion still require scrutiny.

‘If it came from a phone, it is technically certain.’ Integrity, context, attribution, custody and methods must be examined first.

‘Other evidence makes the breach irrelevant.’ Its independence and the disputed item’s actual weight must be assessed.

‘Rejecting the objection means the reasons are sufficient.’ A specific, potentially decisive allegation needs an answer connected to the documents and rules.

‘A private recording is always permitted.’ Method, purpose, necessity, scope and the rights affected depend on the facts.

Conclusion

The central issue is not whether evidence is in the file but what authorities and proceedings do with it. Acquisition requires lawful authority and statutory limits, preserved integrity, effective defence objections and an explicit explanation of the outcome.

Keep three statements distinct: the evidence was obtained unlawfully; it is unreliable; it is insufficient for conviction. They may point towards the same result but have different legal and evidential foundations. A strong review links each objection to its supporting documents and effect on judgment.

Establishing facts and protecting fundamental rights are not competing objectives. Lawful evidence safeguards a legitimate, reviewable outcome. Every stage, from a detail in a search record to image integrity, concerns fairness as a whole as well as procedure.