Universal Jurisdiction in Practice: Procedural and Evidential Challenges for Domestic Courts

Introduction

Universal jurisdiction allows national courts to prosecute certain grave offences irrespective of where they occurred and without direct territorial or nationality links. The doctrine has been adopted in different forms across jurisdictions for offences such as genocide, crimes against humanity, torture and certain war crimes. While the principle has normative appeal, its operationalisation raises complex procedural, evidential and diplomatic problems for domestic courts and those who prosecute before them. This article outlines those challenges and offers practical measures for investigators, prosecutors and defence counsel, with reference to the institutional context of Türkiye and comparative practice.

Key procedural and jurisdictional hurdles

Several recurring procedural obstacles affect universal jurisdiction cases:

• Forum and competence: Determining which court has jurisdiction, and whether domestic law expressly permits extraterritorial competence for the specific offence, is a threshold question that can be dispositive.
• State and functional immunities: Immunities for serving foreign officials remain a live issue. Courts must balance immunity doctrines against exceptions recognised in customary international law for core international crimes, while respecting domestic immunities law and the prospect of diplomatic friction.
• Ne bis in idem and extradition requirements: Prior proceedings abroad, extradition requests and applicable non bis in idem protections may limit prosecutorial options.

Practical implication

Prosecutors should conduct an early jurisdictional and admissibility mapping to identify potential immunities, competing proceedings and necessary legislative authorisations. Defence counsel should interrogate jurisdictional basis at the outset to test for forum non conveniens and immunity-based challenges.

Evidential and investigative challenges

Evidence in universal jurisdiction cases frequently originates in hostile or inaccessible environments. Issues include chain of custody, forensic integrity, translation, reliability of electronic open-source material, and witness availability.

• Preservation and authentication: Early evidence preservation and independent forensic validation are essential. Where possible, contemporaneous metadata, validated collection logs and corroborative witness testimony strengthen admissibility arguments.
• Open-source intelligence (OSINT): Courts are increasingly asked to assess OSINT and social-media evidence. Prosecutors must document collection methodology, provenance and reliability assessments to withstand admissibility scrutiny.
• Witness protection and testimony by videolink: Cross-border witness protection, relocation and secure remote testimony protocols are frequent necessities but require inter-state cooperation and robust procedural safeguards to ensure fairness.

Practical implication

Investigating authorities should prioritise forensic-grade collection practices, chain of custody documentation and independent verification. Where evidence is obtained abroad, early engagement through mutual legal assistance (MLA) channels ensures evidentiary weight and admissibility. Defence teams should examine collection methods rigorously to identify contamination or reliability gaps.

Diplomatic and international cooperation dimensions

Universal jurisdiction cases often intersect with broader diplomatic concerns. Prosecutions may prompt political pushback, reciprocal measures or constraints on cooperation from states whose officials or nationals are implicated.

• MLA and extradition: Requests for documents, witness interviews or suspect surrender commonly rely on MLA treaties and bilateral arrangements. Anticipating delays and refusals is essential.
• Coordination with international bodies: Engagement with international courts, UN investigative mechanisms and regional organisations can supplement domestic efforts and provide independent forensic or investigative support.

Practical implication

Strategic diplomatic engagement by justice ministries often facilitates cooperation. Prosecutors should build relationships with foreign counterparts and multilateral institutions before high-profile filings. Transparency in legal reasoning reduces the risk of politicisation.

Applying the lessons in the Turkish context

Türkiye’s legal and institutional landscape places emphasis on rule-of-law safeguards and international cooperation. Even where domestic statutes permit extraterritorial jurisdiction for specific offences, Turkish authorities will need to navigate immunities, evidentiary hurdles and diplomatic sensitivities. As a practitioner at Şahin Hukuk, I recommend early inter-agency coordination, rigorous forensic standards and a calibrated approach to public communications to preserve judicial credibility and diplomatic channels.

Conclusion: a practitioner checklist

1. Conduct an early jurisdiction and immunity assessment.
2. Secure forensic-grade evidence collection and document chain of custody.
3. Use MLA channels promptly; plan for witness protection and remote testimony.
4. Coordinate with foreign ministries and international investigatory bodies.
5. Prepare to defend the admissibility of OSINT and digital evidence through transparent methodology.

Practitioners should combine legal rigour with practical evidence management and diplomatic awareness to give universal jurisdiction cases the best chance of fair, enforceable outcomes.

Av. Burak Şahin, Şahin Hukuk