18. This power, known as the principle of "Kompetenz-Kompetenz" in German or "la compétence de la compétence" in French, is part, and indeed a major part, of the incidental or inherent jurisdiction of any judicial or arbitral tribunal, consisting of its "jurisdiction to determine its own jurisdiction." It is a necessary component in the exercise of the judicial function and does not need to be expressly provided for in the constitutive documents of those tribunals, although this is often done (see, e.g., Statute of the International Court of Justice, Art. 36, para. 6). But in the words of the International Court of Justice:

"[T]his principle, which is accepted by the general international law in the matter of arbitration, assumes particular force when the international tribunal is no longer an arbitral tribunal […] but is an institution which has been pre-established by an international instrument defining its jurisdiction and regulating its operation." (Nottebohm Case (Liech. v. Guat.), 1953 I.C.J. Reports 7, 119 (21 March).)

This is not merely a power in the hands of the tribunal. In international law, where there is no integrated judicial system and where every judicial or arbitral organ needs a specific constitutive instrument defining its jurisdiction, "the first obligation of the Court - as of any other judicial body - is to ascertain its own competence." (Judge Cordova, dissenting opinion, advisory opinion on Judgements of the Administrative Tribunal of the I.L.O. upon complaints made against the U.N.E.S.C.O., 1956 I.C.J. Reports, 77, 163 (Advisory Opinion of 23 October)(Cordova, J., dissenting).)

[…]

22. In conclusion, the Appeals Chamber finds that the International Tribunal has jurisdiction to examine the plea against its jurisdiction based on the invalidity of its establishment by the Security Council.

61. Appellant argues that he has a right to be tried by his national courts under his national laws. […] Does it prevent Appellant from being tried […] before an international tribunal? […]

62. As a matter of fact - and of law - the principle advocated by Appellant aims at one very specific goal: to avoid the creation of special or extraordinary courts designed to try political offences in times of social unrest without guarantees of a fair trial.

This principle is not breached by the transfer of jurisdiction to an international tribunal created by the Security Council acting on behalf of the community of nations. No rights of accused are thereby infringed or threatened; quite to the contrary, they are all specifically spelt out and protected under the Statute of the International Tribunal. No accused can complain. True, he will be removed from his "natural" national forum; but he will be brought before a tribunal at least equally fair, more distanced from the facts of the case and taking a broader view of the matter. […]

45. […] The important consideration in determining whether a tribunal has been "established by law" is not whether it was pre-established or established for a specific purpose or situation; what is important is that it be set up by a competent organ in keeping with the relevant legal procedures, and that it observes the requirements of procedural fairness. […]

46. An examination of the Statute of the International Tribunal, and of the Rules of Procedure and Evidence adopted pursuant to that Statute leads to the conclusion that it has been established in accordance with the rule of law. The fair trial guarantees in Article 14 of the International Covenant on Civil and Political Rights have been adopted almost verbatim in Article 21 of the Statute. Other fair trial guarantees appear in the Statute and the Rules of Procedure and Evidence. For example, Article 13, paragraph 1, of the Statute ensures the high moral character, impartiality, integrity and competence of the Judges of the International Tribunal, while various other provisions in the Rules ensure equality of arms and fair trial.

47. In conclusion, the Appeals Chamber finds that the International Tribunal has been established in accordance with the appropriate procedures under the United Nations Charter and provides all the necessary safeguards of a fair trial. It is thus "established by law."

99. […] When attempting to ascertain State practice with a view to establishing the existence of a customary rule or a general principle, it is difficult, if not impossible, to pinpoint the actual behaviour of the troops in the field for the purpose of establishing whether they in fact comply with, or disregard, certain standards of behaviour. This examination is rendered extremely difficult by the fact that not only is access to the theatre of military operations normally refused to independent observers (often even to the ICRC) but information on the actual conduct of hostilities is withheld by the parties to the conflict; what is worse, often recourse is had to misinformation with a view to misleading the enemy as well as public opinion and foreign Governments. In appraising the formation of customary rules or general principles one should therefore be aware that, on account of the inherent nature of this subject-matter, reliance must primarily be placed on such elements as official pronouncements of States, military manuals and judicial decisions.

[…]

126. The emergence of the aforementioned general rules on internal armed conflicts does not imply that internal strife is regulated by general international law in all its aspects. Two particular limitations may be noted: (i) only a number of rules and principles governing international armed conflicts have gradually been extended to apply to internal conflicts; and (ii) this extension has not taken place in the form of a full and mechanical transplant of those rules to internal conflicts; rather, the general essence of those rules, and not the detailed regulation they may contain, has become applicable to internal conflicts. […]

127. Notwithstanding these limitations, it cannot be denied that customary rules have developed to govern internal strife. These rules, as specifically identified in the preceding discussion, cover such areas as protection of civilians from hostilities, in particular from indiscriminate attacks, protection of civilian objects, in particular cultural property, protection of all those who do not (or no longer) take active part in hostilities, as well as prohibition of means of warfare proscribed in international armed conflicts and ban of certain methods of conducting hostilities.

143. […] It should be emphasised again that the only reason behind the stated purpose of the drafters that the International Tribunal should apply customary international law was to avoid violating the principle of nullum crimen sine lege in the event that a party to the conflict did not adhere to a specific treaty. (Report of the Secretary-General, at para. 34.) It follows that the International Tribunal is authorised to apply, in addition to customary international law, any treaty which: (i) was unquestionably binding on the parties at the time of the alleged offence; and (ii) was not in conflict with or derogating from peremptory norms of international law, as are most customary rules of international humanitarian law. […]

89. […] Article 3 [of the ICTY Statute] is a general clause covering all violations of humanitarian law not falling under Article 2 or covered by Articles 4 or 5, more specifically: (i) violations of the Hague law on international conflicts; (ii) infringements of provisions of the Geneva Conventions other than those classified as "grave breaches" by those Conventions; (iii) violations of common Article 3 and other customary rules on internal conflicts; (iv) violations of agreements binding upon the parties to the conflict, considered qua treaty law, i.e., agreements which have not turned into customary international law (on this point see below, para. 143).

90. […] It is therefore appropriate to take the expression "violations of the laws or customs of war" to cover serious violations of international humanitarian law.

91. Article 3 thus confers on the International Tribunal jurisdiction over any serious offence against international humanitarian law not covered by Article 2, 4 or 5. Article 3 is a fundamental provision laying down that any "serious violation of international humanitarian law" must be prosecuted by the International Tribunal. In other words, Article 3 functions as a residual clause designed to ensure that no serious violation of international humanitarian law is taken away from the jurisdiction of the International Tribunal. Article 3 aims to make such jurisdiction watertight and inescapable.

50. In articulating its approach to evidence presented in rebuttal to adjudicated facts, the Trial Chamber specified, in part, as follows:

The Trial Chamber analysed the evidence and considered, as an initial step, whether evidence contradicted the Adjudicated Facts. The Trial Chamber required evidence to be unambiguous in its meaning in order to be termed as ‘contradicting the Adjudicated Facts’. For example, evidence suggesting mere possibilities was deemed not to reach that threshold. In other words, merely pointing at the possibility of alternative scenarios was in itself not sufficient ground to reopen the evidentiary debate. A contradiction can exist in either presenting evidence on a specific alternative scenario, as opposed to a mere suggestion of one or more possible alternative scenarios, or in the unambiguous demonstration that the scenario as found in the Adjudicated Fact must reasonably be excluded as true. […] The Trial Chamber was mindful that evidence contradicting adjudicated facts does not automatically rebut the adjudicated fact. The presumption of accuracy of the adjudicated fact is only rebutted by ‘reliable and credible’ contradictory evidence.[1]

 […]

54.  […] The ICTR Appeals Chamber in the Karemera et al. case has clarified that “the effect [of judicially noticing an adjudicated fact] is only to relieve the Prosecution of its initial burden to produce evidence on the point; the defence may then put the point into question by introducing reliable and credible evidence to the contrary”.[2]  In this respect, Mladić contends that “[t]he need for rebuttal evidence to be ‘credible and reliable’ […] must be read in light of the general standard for the admissibility of evidence”,[3] which is “relatively low”,[4] and “was never intended to be applied in conjunction with an additional requirement that the evidence be 'unambiguous’”.[5] He argues that the Trial Chamber’s error in heightening the standard resulted in his evidence being deemed “insufficient to enliven the rebuttal procedure or to rebut the accuracy of the adjudicated fact”.[6]

55.   In the Appeals Chamber’s view, Mladić confuses the standard for the admissibility of evidence with the final evaluation thereof. A reading of the Trial Judgement shows that the Trial Chamber’s criterion of unambiguity was not related to the reliability or credibility of evidence, but rather to its contrary nature.[7] In accordance with the standard elucidated by the ICTR Appeals Chamber in the Karemera et al. case, in order for evidence presented in rebuttal of an adjudicated fact to be admissible, and thereby bringing the presumption of its accuracy into dispute, such evidence must be contrary to the adjudicated fact and bear sufficient indicia of prima facie reliability and credibility.[8] The Appeals Chamber stresses, however, that “adjudicated facts that are judicially noticed […] remain to be assessed by the Trial Chamber to determine what conclusions, if any, can be drawn from them when considered together with all the evidence brought at trial”.[9] As such, the final evaluation of the probative value of rebuttal evidence, which includes a final assessment of its reliability and credibility, as well as the extent to which it is consistent with or contradicts adjudicated facts, “will only be made in light of the totality of the evidence in the case, in the course of determining the weight to be attached to it”.[10]

56.   In light of the above, and considering that, once judicially noticed, an adjudicated fact is presumed to be true, the Appeals Chamber finds no dissonance in the Trial Chamber’s requirement that evidence produced in rebuttal thereof should be “unambiguous in its meaning” – namely that it must either point to “a specific alternative scenario” or “unambiguous[ly] demonstrat[e] that the scenario as found in the Adjudicated Fact must reasonably be excluded as true”[11] – in order to successfully contradict it. […]

488.  […] The Appeals Chamber recalls ICTY Appeals Chamber jurisprudence holding that Article 3 of the ICTY Statute is a general and residual clause which refers to a broad category of offences, namely all “violations of the laws or customs of war”, not limited to the list of violations enumerated therein.[1] The ICTY Appeals Chamber has consistently held that Article 3 of the ICTY Statute may cover all violations of international humanitarian law not falling under Articles 2, 4, or 5 of the ICTY Statute, including violations of Common Article 3,[2] which contains a prohibition of hostage-taking.[3] The Appeals Chamber further recalls that the ICTY Appeals Chamber in the Tadić case examined, inter alia, findings of the International Military Tribunal at Nuremberg, domestic prosecutions, military manuals and legislation – including the law of the former Yugoslavia – and Security Council resolutions, and confirmed the formation of opinio juris to the effect that customary international law imposes criminal liability for those who commit serious violations of Common Article 3.[4] Furthermore, the ICTY Appeals Chamber has previously rejected arguments that there are cogent reasons to depart from the Tadić jurisprudence on the questions of whether Common Article 3 is included in the scope of Article 3 of the ICTY Statute[5] and whether breaches of its provisions give rise to individual criminal responsibility.[6] The ICTY Appeals Chamber has stated that the acts enumerated in Common Article 3 were intended to be criminalized within the international legal order as early as 1949.[7]

489.  Furthermore, the ICTY has exercised its jurisdiction under Article 3 of the ICTY Statute to try individuals for violations of Common Article 3,[8] including on the basis of hostage-taking.[9] In this respect, the ICTY Appeals Chamber in the Karadžić case upheld the ICTY Trial Chamber’s determination that the ICTY had jurisdiction over the crime of hostage-taking under Article 3 of the ICTY Statute.[10] The ICTY Appeals Chamber has held that, under Common Article 3, there is an absolute prohibition of taking hostage of any person taking no active part in hostilities as well as detained individuals irrespective of their status prior to detention.[11] It has also rejected the submission that the crime of hostage-taking is limited under customary international law to the taking of civilians hostage.[12] In light of this jurisprudence, the Appeals Chamber considers that the matter of the ICTY’s jurisdiction over the crime of hostage-taking was settled by the ICTY Appeals Chamber.

490.  In attempting to demonstrate that there are cogent reasons to depart from this well established jurisprudence, Mladić submits that during the Indictment period, with the exception of the killing of hostages or the taking of civilians hostage, the taking of “non-civilians” hostage was not prohibited and did not entail individual criminal responsibility under customary international law. Mladić’s argument that the laws and norms applicable to the International Military Tribunal at Nuremberg only apply to the killing of hostages[13] does not undermine the fact that the prohibition of hostage-taking of any person taking no active part in the hostilities was nevertheless well established in customary international law during the period covered by the Indictment and entailed individual criminal responsibility. The Appeals Chamber recalls that Article 4 of the ICTR Statute, which was adopted in 1994, expressly prohibits hostage-taking as a violation of Common Article 3 and Additional Protocol II. The ICTY Appeals Chamber has stated that the ICTR applies existing customary international law and that it was established to prosecute crimes which were already the subject of individual criminal responsibility.[14] Furthermore, an analysis of state practice confirms the formation of opinio juris that customary international law imposes individual criminal responsibility for violations of Common Article 3 and Additional Protocol II during the Indictment period. For example, legislation and military manuals of a number of states prohibited such violations,[15] and Additional Protocol II, which specifically contains the prohibition against hostage-taking of “[a]ll persons who do not take a direct part or who have ceased to take part in hostilities, whether or not their liberty has been restricted”, was adopted in 1977 by consensus and had been ratified by over 120 states at the time of the events included in the Indictment.[16]