The Appeals Chamber held in paragraph 19 of the decision that:

19. Rules 15bis (D) of the Rules confers on the remaining Judges the discretion to determine whether to continue the trial proceedings with a substitute Judge. In exercising this discretion, the remaining Judges have “the right to establish the precise point within a margin of appreciation at which a continuation [of the proceedings] should be ordered”.[1] The Appeals Chamber has previously stated that it can only intervene in this decision-making process in limited circumstances, as, for example, where it is of the view that there was a failure to exercise the discretion, or that the remaining Judges failed to take into account a material consideration or took into account an immaterial one and that the substance of its decision has in consequence been affected.[2] It is not enough to show that the Appeals Chamber would have exercised the discretion differently.[3]

12.     With the arrest of Judge Akay, proceedings on the merits of Ngirabatware’s Request for Review have necessarily come to a standstill. To move the case forward, as suggested by the Prosecution,[1] by the substitution of a judge as a first reaction in response to the current situation is nothing short of violating a core principle that is fundamental to the administration of justice: an independent judiciary.

13.     I have long maintained that upholding the integrity of our judicial system entails not exercising the powers conferred upon me as President arbitrarily and eschewing improper influences when determining the composition of judicial benches.[2] It is […] evident […] that reassignment of Judge Akay onto another case is simply an unfair and myopic solution since it would similarly halt proceedings in that case. While pragmatic, this solution will undoubtedly impinge on the fundamental principle of judicial independence as it would allow interference by a national authority in the conduct of a case and the exercise of judicial functions. As such, it will have a chilling effect on the administration of justice. Moreover, the inherent authority of the Mechanism cannot be interpreted, as the Prosecution suggests, [3] to include taking substantive decisions on the merits of a case in the absence of the consideration by all of the members of the bench. Judge Akay’s views on this case matter to our solemn deliberations, and, in the present circumstances, decisions on the merits of this case cannot be taken even should they hold the support of a majority of the remaining judges. Moreover, it cannot be said that the integrity of the judicial system would be upheld if a replacement of a judge is viewed as a measure of first rather than last resort, especially where the avenues for the Government of the Republic of Turkey to implement the United Nations Secretary-General’s assertion of immunity have neither been fully explored nor exhausted, including the execution of this request made by Ngirabatware. In this regard, I note that Judge Akay’s release is also being sought pursuant to domestic legal proceedings in Turkey. An application before the European Court of Human Rights has also been filed.[4]

[…]

15.     This is not to say that judges can never be reassigned or replaced. But a judge has been arrested, immunity has been asserted, it has not been waived, and Judge Akay’s continued presence on the bench has the full support of the person who is seeking relief. Judge Akay is an essential member of this bench. In the absence of extraordinary circumstances, his continued presence on the bench is essential to the preservation of judicial independence. To say Judge Akay can be replaced easily to facilitate the judicial process – at this initial stage and before other avenues have been exhausted – is to say we do not value judicial independence, value justice, value what is right.