At para. 6, the Appeals Chamber confirmed that it has no power to reconsider final judgments.

See Prosecutor v. Zoran Žigić, Case No. IT-98-30/1-A, Decision on Zoran Žigić’s “Motion for Reconsideration of Appeals Chamber Judgement IT-98-30/1-A Delivered on 28 February 2005”, 26 June 2006; Prosecutor v. Eliézer Niyitegeka, Case No. ICTR-96-14-R, Decision on Request for Reconsideration of the Decision on Request for Review, 27 September 2006 (“Niyitegeka Reconsideration Decision”).

The Appeals Chamber noted that while there were many precedents confirming the Appeals Chamber’s power to reconsider its decisions, there was only one precedent of a reconsideration of a judgement, namely the Čelebići Judgement on Sentence Appeal. It then recalled the “standards of reconsideration” as stated in that judgement (paras 5-6), according to which a judgement can be reconsidered when there is a “prospect of injustice” (paras 5-6). Part of the reasoning of the Appeals Chamber in the Čelebići Judgement on Sentence Appeal was that the right of review on the discovery of a new fact, granted by Article 26 of the Tribunal’s Statute is “only a partial answer to the prospect of injustice”.[1] In the present case, the Appeals Chamber however noted that the requirement of a “new fact” under Article 26 of the Statute has been interpreted broadly (para. 7):

7. While the Čelebići Judgement on Sentence Appeal considered that review proceedings under Article 26 of the Statute of the Tribunal constituted a limited answer to the possibility of injustice, the Appeals Chamber notes that the jurisprudence of this Tribunal has nonetheless shown that when proceedings are brought under that Article, the requirement of the existence of a “new fact” has been interpreted broadly, and the conditions of knowledge and due diligence required under Rule 119 of the Rules of Procedure and Evidence of the Tribunal have been waived in “wholly exceptional circumstances” and “where the impact of a new fact on the decision would be such that to ignore it would lead to a miscarriage of justice”.[2]

It held that “in effect” parties “typically” use the reconsideration procedure to lodge a second appeal (para. 8) and consequently held that “there is no power to reconsider a final judgement”:

7. To allow a person whose conviction has been confirmed on appeal the right to further contest the original findings against them on the basis of mere assertions of errors of fact or law is not in the interests of justice to the victims of the crimes or the convicted person, who are both entitled to certainty and finality of legal judgements. Nor is it consistent with the Statute of this Tribunal, which provides for a right of appeal and a right of review but not for a second right of appeal by the avenue of reconsideration of a final judgement.  The Appeals Chamber is satisfied that the existing appeal and review proceedings established under the Statute provide sufficient guarantees to persons convicted before this Tribunal that they have been tried fairly and in accordance with norms of due process. In light of these considerations, the Appeals Chamber has come to the view that cogent reasons in the interests of justice[3] demand its departure from the majority opinion in the Čelebići Judgement on Sentence Appeal. Accordingly, this Appeals Chamber holds that there is no power to reconsider a final judgement.  The Appeals Chambers notes, however, that its departure from Čelebići does not affect the power of the Tribunal to reconsider its decisions, which cannot be subject to review proceedings. (emphasis added). 

See also Judge’s Shahabuddeen “Declaration”.

598. […] [T]he Appeals Chamber recalls that it is not bound by the findings of other courts – domestic, international, or hybrid – and that, even though it will consider such jurisprudence, it may nonetheless come to a different conclusion on a matter than that reached by another judicial body.[1] The Appeals Chamber considers that in order to constitute a cogent reason for departing from its established jurisprudence on a matter, the party advocating a departure would need to show that a non‑binding opinion of another court is the correct law and demonstrate that there is a clear mistake in the Appeals Chamber’s approach.[2] […]