President of the Turkish Constitutional Court, Mr. Kadir Özkaya, stating that the Court has become a significant actor in a multi-layered system of human rights protection that has evolved in interaction with international human rights law, further noted: “With the introduction of the individual application mechanism, the Turkish Constitutional Court has evolved into a body of jurisprudence serving as a bridge between domestic law and international human rights law.”

As part of the events marking the 64^th anniversary of the Turkish Constitutional Court, a symposium on “The Impact of the Ne Bis in Idem Principle in Different Jurisdictions” was held under the Project on “Supporting the Effective Implementation of Turkish Constitutional Court Judgments in the Field of Fundamental Rights”, which is undertaken jointly by the Constitutional Court and the European Union–Council of Europe. Among those attending the event, organised on 27 April 2026 at the Grand Tribunal Hall of the Court, were President of the Constitutional Court Mr. Kadir Özkaya, President of the Court of Cassation Mr. Ömer Kerkez,  Chair of the Constitutional Committee of the Grand National Assembly of Türkiye Prof. Dr. Serap Yazıcı Özbudun, Judge of the European Court of Human Rights (ECHR) in respect of Türkiye Prof. Dr. Saadet Yüksel, Chief Public Prosecutor of the Council of State Mr. Cevdet Erkan, Head of the Council of Europe Ankara Programme Office Mr. William Massolin, as well as members of the high courts, jurists and academics.

In his opening remarks, President Özkaya emphasised that constitutional justice is not merely a technical review mechanism, but an institutional safeguard that upholds the supremacy and binding force of the Constitution. Noting that the Turkish Constitutional Court, established under the 1961 Constitution, constitutes the most concrete manifestation of constitutional justice, President Özkaya stated: “In this respect, the Court represents not only the establishment of a new judicial body, but also the judicial protection of the principle of the supremacy of the Constitution. This, in turn, confirms that the Court stands as one of the strongest guarantors of the rule of law in Türkiye.”

President Özkaya, noting that the Court discharges its duties and responsibilities in light of this approach, highlighted the individual application mechanism introduced by the 2010 constitutional amendments as one of the key milestones in the Court’s history. He further stated that, drawing on its 64-year legacy, the Turkish Constitutional Court has become an important actor not only within the Turkish legal system, but also in a multi-layered human rights protection mechanism developed through interaction with international human rights law.

Constitutional justice is one of the indispensable pillars of a democratic state governed by the rule of law

Stating that constitutional justice is one of the indispensable pillars of a democratic state governed by the rule of law, President Özkaya noted that, in the absence of constitutionality review, the principle of the supremacy of the Constitution would remain devoid of practical effect. He described constitutional justice as a mechanism not merely confined to the annulment of legal norms, adding: “It may be regarded as a mechanism actively contributing to the process of democratisation, extending beyond the protection of rights and freedoms to their further development.”

He emphasised that, particularly with the introduction of the individual application mechanism, the Turkish Constitutional Court has become not only a body offering redress for human rights violations but also a centre of jurisprudence guiding the legal system as a whole. He accordingly referred to the Court as a body of jurisprudence serving as a bridge between domestic law and international human rights law through the individual application mechanism.

President Özkaya stated that this historical development demonstrates not only institutional continuity, but also the Court’s capacity to respond to evolving social needs. He further noted that the effective operation of the individual application mechanism, the adjudication of cases within a reasonable time despite the growing number of applications, and the transformative effect of violation judgments on the legal order clearly illustrate the dynamic nature of constitutional justice. 

President Özkaya remarked that the Turkish Constitutional Court contributes, on the one hand, to the protection of fundamental rights and freedoms through individual applications and, on the other hand, develops a coherent body of jurisprudence that guides the exercise of public authority and prevents the recurrence of similar violations. He accordingly described constitutional justice as not being merely a mechanism for adjudicating individual disputes, but also one with a normative and transformative role in shaping the legal order as a whole.

President Özkaya further stated that, with the introduction of the individual application mechanism, the Court has developed a judicial practice generating both a subjective effect, ensuring the protection of individual rights, and an objective effect, contributing to the transformation of the legal order. Referring also to the interaction with the case-law of the ECHR, he noted that this engagement has brought constitutional justice into a more universal and comparative perspective, thereby creating a robust framework for judicial dialogue.

Pointing to the continuous process of development and transformation that the Court has undergone in line with the principles of transparency, accessibility, and efficiency, President Özkaya said that the expansion of digital tools has facilitated individual application procedures. He added that the timely and systematic publication of the Court’s judgments gives concrete effect to the principle of transparency in constitutional justice, thereby demonstrating that constitutional justice fulfils not only a legal function but also a role in fostering institutional trust and democratic legitimacy.

President Özkaya, referring to the theme of this year’s symposium, “The Impact of the Ne Bis in Idem Principle in Different Jurisdictions”, emphasised that this principle represents one of the most significant areas of development in the Court’s case-law. He further stated that although the ne bis in idem principle is not expressly enshrined in the 1982 Constitution, the Turkish Constitutional Court has regarded it as an inherent element of the rule of law and the right to a fair trial. He accordingly added: “In its individual application judgments, the Court views this principle not merely as a technical rule specific to criminal law, but as a constitutional safeguard protecting legal certainty and the finality of judicial proceedings.”

Stating that the mere existence of multiple sanctions in respect of the same act does not in itself amount to a violation, President Özkaya added: “What is essential is whether these sanctions protect the same legal interest and whether they are sufficiently interconnected.” He observed that the issues arising particularly at the intersection of tax law, administrative sanctions, and criminal law render the application of this principle increasingly complex and accordingly stated: “In the face of this complexity, the jurisprudence of the Turkish Constitutional Court plays a decisive role not only in domestic law but also in ensuring compliance with international human rights law. In this context, the ne bis in idem principle is no longer merely a prohibition, but rather a constitutional mechanism of balance ensuring coherence between legal systems, harmonising different sanctioning regimes, and placing the protection of the individual at its core.”

Expressing his sincere belief that the symposium would contribute to a deeper understanding of the ne bis in idem principle in the light of the Court’s case-law, President Özkaya voiced his hope that efforts aimed at strengthening the rule of law and ensuring the effective protection of fundamental rights would continue to progress.

Turkish Constitutional Court’s jurisprudence represents a valuable legacy that places individual rights and freedoms at its core and reinforces the sense of justice

In her opening remarks, Turkish Judge at the ECHR, Prof. Dr. Saadet Yüksel, highlighted the importance of the ne bis in idem principle in both domestic and international law, and provided an assessment of its place in the ECHR’s case-law. Drawing attention to the coherence between the case-law of the Turkish Constitutional Court and that of the ECHR in the context of this principle, Ms. Yüksel stated: “The Turkish Constitutional Court is not only part of the European tradition of constitutional justice, but also one of its relatively early-established, reputable and experienced institutions. The Court’s influence on the European system of human rights protection extends well beyond the borders of Türkiye. Through both its judgments and its institutional relations, the Turkish Constitutional Court is an indispensable part not only of the Turkish legal order but also of the European judicial community. The Turkish Constitutional Court’s jurisprudence represents a valuable legacy that guides the development of a democratic state governed by the rule of law, places individual rights and freedoms at its core and reinforces the sense of justice.”

In his opening remarks, Head of the Council of Europe Ankara Programme Office, Mr. William Massolin, also stated that the symposium is of significant value, as it enables the ne bis in idem principle, which is of vital importance for judicial systems, to be addressed from different perspectives. Referring to the legal and social role of the Turkish Constitutional Court, Mr. Massolin highlighted the significant progress achieved within the framework of the project implemented jointly by the Constitutional Court and the European Union–Council of Europe. He emphasised his belief that the results achieved and the gains made would continue to have positive implications in the period ahead, and also extended his congratulations on the 64^th anniversary of the Turkish Constitutional Court.

The opening remarks were followed by the academic session, where the prohibition of double jeopardy in respect of the same act was addressed in its various dimensions in the light of the ne bis in idem principle and from a constitutional perspective. Vice-President of the Turkish Constitutional Court, Mr. Basri Bağcı, who chaired the session, highlighted the importance of the academic session focusing on the theoretical and practical aspects of the ne bis in idem principle, one of the most fundamental principles of both national and international law. The symposium featured presentations by Chief Rapporteur-Judge of the Constitutional Court Assoc. Prof. Dr. Akif Yıldırım, Member of the 10^th Criminal Chamber of the Court of Cassation Dr. Harun Mert, Member of the 13^th Chamber of the Council of State Mr. Fatih Mehmet Alkış, as well as Prof. Dr. Feridun Yenisey, who joined the symposium online.

The ne bis in idem principle has become a stronger safeguard in the context of constitutional criminal law with the introduction of the individual application mechanism

In his closing remarks at the symposium, which featured question-and-answer session during the academic panel, Vice-President of the Turkish Constitutional Court, Mr. İrfan Fidan, underlined that the ne bis in idem principle is not merely a technical rule of criminal law prohibiting double prosecution or punishment for the same act, but constitutes a fundamental safeguard of the rule of law, legal certainty, and the protection of the individual vis-à-vis the State. He stated that the presentations delivered throughout the day revealed the multi-layered nature of the principle in terms of criminal law, administrative law, constitutional law and human rights law, and noted that, particularly with the introduction of the individual application mechanism, the principle has become a stronger safeguard in the context of constitutional criminal law. Mr. Fidan emphasised that such academic and institutional cooperation across different jurisdictions plays an important role in strengthening the rule of law, and expressed his appreciation to all those who contributed to the successful organisation of the symposium.

Click for the full text of the remarks delivered by President Kadir Özkaya.