Constitutional Court Decision on the Processing of Genetic Data in Criminal Proceedings

Selin Çetin Kumkumoğlu

Counsel

selin.cetin@kecoslegal.com

Yaren Alparslan

Associate

yaren.alparslan@kecoslegal.com

The decision of the Constitutional Court (“Court”), dated 25 December 2025 and numbered E.2025/141, K.2025/274, published in the Official Gazette dated 18 March 2026 and numbered 33200 (“Decision”), focuses on whether certain provisions of the Criminal Procedure Code No. 5271 (“CPC”) concerning the processing and destruction of genetic data provide adequate safeguards in terms of the right to the protection of personal data. Within the scope of the objection application filed by the Istanbul Anatolian 90th Criminal Court of First Instance, the Court particularly examined Article 80(2) and Article 82 of the CPC (insofar as it relates to Article 80(2)).

The core issue of the dispute concerns whether the conditions under which genetic data obtained from suspects, accused persons, or victims during criminal proceedings are stored and destroyed are regulated in a sufficiently clear and foreseeable manner. The Court first assessed the nature of genetic data and emphasized that such data constitute special categories of personal data under the Law on the Protection of Personal Data No. 6698 (“DPL”), and therefore must be subject to stricter constitutional safeguards.

In its assessment, the Court noted that, pursuant to Article 28 of the DPL, personal data processed within the scope of criminal investigations and prosecutions fall outside the scope of the DPL. Accordingly, the Court underlined that this necessitates that the fundamental safeguards applicable to genetic data processed in criminal proceedings be directly regulated under the relevant statutory provisions.

Within this framework, the Court examined Article 80(2) of the CPC and determined that the provision only mandates the immediate destruction of genetic data in specific cases, such as a decision of non-prosecution, acquittal, or a decision of no need to impose a penalty. However, it found that the provision does not regulate essential aspects for other scenarios (such as conviction, dismissal, or discontinuance of the case), including the duration for which such data may be retained, the conditions for their destruction, and whether data subjects have rights of access or erasure. The Court considered that this deficiency could allow for the indefinite or indeterminate retention of genetic data.

According to the Court, any restriction on the right to the protection of personal data must, pursuant to Articles 13 and 20 of the Constitution, be prescribed by law and must be formulated in a manner that is clear, foreseeable, and provides safeguards against arbitrariness. The Court concluded that the contested provision fails to meet these requirements, as it does not establish an adequate legal framework governing the scope, duration, and limits of data processing. Accordingly, it was held that the provision does not satisfy the principle of legality and is also incompatible with the principle of proportionality.

With respect to Article 82 of the CPC, the Court further evaluated the provision stipulating that the procedures and principles regarding the collection, storage, and destruction of genetic data shall be regulated by secondary legislation. In this regard, the Court emphasized that fundamental aspects of restrictions on fundamental rights and freedoms must be regulated by law. It concluded that leaving the regulation of essential matters, such as the retention and destruction of genetic data, data subjects’ rights, and available remedies, to the administration without establishing a clear statutory framework is incompatible with the principle of non-delegation of legislative power and the principle of legality.

As a result, the Constitutional Court ruled, by majority, that Article 80(2) and Article 82 of the CPC (insofar as it relates to Article 80(2)) are unconstitutional as they violate Articles 13 and 20 of the Constitution, and annulled these provisions. Considering that the annulment could create a legal vacuum detrimental to public interest, the Court decided that the annulment would enter into force nine months after the publication of the Decision in the Official Gazette.

Assessment

This Decision is significant in that it underscores the legislator’s obligation to adopt a more detailed, clear, and safeguard-oriented legal framework governing the processing of genetic data obtained in the course of criminal proceedings.