The editorial board of the Leiden Journal of International Law is pleased to announce a debate on a very important but underexposed topic in international criminal law: witness proofing. Witness proofing is an accepted and well-established practice at the International Criminal Tribunal for the former Yugoslavia (ICTY), the International Criminal Tribunal for Rwanda (ICTR), and the Special Court for Sierra Leone (SCSL). It entails setting up a meeting between a party to the proceedings and a witness, usually shortly before the witness is to testify in court, the purpose of which is to prepare and familiarize the witness with courtroom procedure and to review the witness's evidence. Recently a trial chamber of the International Criminal Court (ICC) prohibited witness proofing. On 30 November 2007, Trial Chamber I held in the Lubanga case that the possibility of witness proofing is not expressly provided for in the ICC Statute and its Rules of Procedure and Evidence, and that no general principle exists in national or international criminal law that would require the ICC to adhere to such a practice. Moreover, and this is the most interesting argument, the trial chamber held that the ICC Statute ‘moves away from the procedural regime of the ad hoc tribunals’ and that as a result witness proofing is not easily transferable to the ICC.

In an article published in this issue Karemaker, Taylor, and Pittman discuss witness proofing at the ad hoc Tribunals, its rationale, and why the ICC should reconsider its position on this issue. The LJIL editorial board has invited Kai Ambos, Professor of Comparative and International Criminal Law at the University of Göttingen, to respond to this position, an invitation he has kindly accepted. In an essay to be published in the next issue Ambos will take issue with the position adopted by Karemaker, Taylor, and Pittman, making it clear that in his view the truly mixed adversarial–inquisitorial procedure set out by the ICC Statute does not sit easily with the adversarial origins of witness proofing, and, moreover, that the ICC's governing law does not provide for it. A brief reply to Ambos's response by Karemaker, Taylor, and Pittman also to be published in the next issue, will bring to a close an instructive and insightful debate on a very important topic.