21. With regard to errors of fact, the party alleging this type of error in support of an appeal against conviction must show the error that was committed and the miscarriage of justice resulting therefrom.[1] It is an established principle that a high degree of deference must be shown to the factual findings of a Trial Chamber, and the Appeals Chamber has regularly recalled that it will not lightly disturb findings of fact by a Trial Chamber.[2] Such deference is based essentially on the fact that the Trial Chamber has the advantage of observing witnesses in person and hearing them when they are testifying,[3] and so are better placed to choose between divergent accounts of one and the same event. Trial Judges are better placed than the Appeals Chamber to assess witness reliability and credibility,[4] and to determine the probative value to ascribe to the evidence presented at trial.[5]

[…]

367. […] In the absence of any showing by the Appellant that no reasonable trier of fact could have discounted [the] evidence, the Appeals Chamber must a priori give a margin of deference to the Trial Chamber’s assessment of the evidence presented at trial and to its factual findings, as the Trial Chamber is best placed to hear the witnesses and assess the probative value of their evidence.[6] […]

[…]

512. The Appeals Chamber recalls that with regard to errors of fact, the appealing party must show both the error that was committed and the miscarriage of justice resulting there from.[7] It is therefore futile on appeal to repeat arguments that failed at trial, unless it can be demonstrated that the dismissal of such arguments actually resulted in an error. With respect to miscarriage of justice, the Appeals Chamber has already specified that the Appellant must show that it was critical to the verdict reached by the Trial Chamber[8] or that the assessment of the evidence was totally erroneous,[9] and that, therefore, flagrant injustice resulted there from.

See also paras. 362, 386.

178.    With respect to errors of fact, the Appeals Chamber confirms that the standard to be applied is the standard of reasonableness of the impugned finding, it being understood that “it is not any and every error of fact which will cause the Appeals Chamber to overturn a decision of the Trial Chamber, but one which has led to a miscarriage of justice.”[1] The onus is therefore on the Appellant to show that an error was committed by the Chamber, which error occasioned a miscarriage of justice. ICTY Appeals Chamber has, on several occasions, applied this standard which can be summed up as follows:

[..].  The test to be applied in relation to the issue as to whether the evidence is factually sufficient to sustain a conviction is whether the conclusion of guilt beyond reasonable doubt is one which no reasonable tribunal of fact could have reached.  If an appellant is not able to establish that the Trial Chamber’s conclusion of guilt beyond reasonable doubt was one which no reasonable tribunal of fact could have reached, it follows that there must have been evidence upon which such a tribunal could have been satisfied beyond reasonable doubt of that guilt.  Under those circumstances, the latter test of legal sufficiency is therefore redundant, and the appeal must be dismissed.  Similarly, if an appellant is able to establish that no reasonable tribunal of fact could have reached a conclusion of guilt upon the evidence before it, the appeal against conviction must be allowed and a Judgment of acquittal entered.  In such a situation it is unnecessary for an appellate court to determine whether  there was evidence (if accepted) upon which  such a tribunal could have reached such a conclusion.[2]

[…]

232.    […] [T]he Appeals Chamber recalls that appellate proceedings are not intended as a trial de novo.  In this case, the Appeals Chamber is guided by the following standard: “The task of hearing, assessing and weighing the evidence presented at trial is left to the Judges sitting in a Trial Chamber. […] It is only where the evidence relied on by the Trial Chamber could not reasonably have been accepted by any reasonable person that the Appeals Chamber can substitute its own finding for that of the Trial Chamber”.[3]

9. When considering an alleged error of fact with respect to a particular ground where no additional evidence has been admitted on appeal, the Appeals Chamber will apply a standard of reasonableness in reviewing the finding.[1] […] In determining whether or not a Trial Chamber’s finding was reasonable, the Appeals Chamber does not lightly disturb findings of fact made by a Trial Chamber.[2] The Appeals Chamber recalls, as a general principle, the approach adopted by the Appeals Chamber in the Kupreškić et al. case, wherein it was stated that […].

37. As to an allegation that there was an error of fact, this Chamber agrees with the following principle set forth by the Appeals Chamber for the International Criminal Tribunal for Rwanda (“the ICTR”)[1] in Serushago:

Under the Statute and the Rules of the Tribunal, a Trial Chamber is required as a matter of law to take account of mitigating circumstances. But the question of whether a Trial Chamber gave due weight to any mitigating circumstance is a question of fact. In putting forward this question as a ground of appeal, the Appellant must discharge two burdens. He must show that the Trial Chamber did indeed commit the error, and, if it did, he must go on to show that the error resulted in a miscarriage of justice.[2]

Similarly, under Article 25(1)(b) of the ICTY Statute, it is not any and every error of fact which will cause the Appeals Chamber to overturn a decision of the Trial Chamber, but one which has led to a miscarriage of justice.  A miscarriage of justice is defined in Black’s Law Dictionary as “a grossly unfair outcome in judicial proceedings, as when a defendant is convicted despite a lack of evidence on an essential element of the crime.”[3]  This Chamber adopts the following approach taken by the Appeals Chamber in the Tadić case[4] in dealing with challenges to factual findings by Trial Chambers:

[t]he task of hearing, assessing and weighing the evidence presented at trial is left to the judges sitting in a Trial Chamber.  Therefore, the Appeals Chamber must give a margin of deference to a finding of fact reached by a Trial Chamber.  It is only where the evidence relied on by the Trial Chamber could not reasonably have been accepted by any reasonable person that the Appeals Chamber can substitute its own finding for that of the Trial Chamber.  It is important to note that two judges, both acting reasonably, can come to different conclusions on the basis of the same evidence.[5]

The position taken by this Chamber in the Tadić Appeals Judgement has been reaffirmed in the Aleksovski Appeals Judgement.[6]  The reason the Appeals Chamber will not lightly disturb findings of fact by a Trial Chamber is well known; the Trial Chamber has the advantage of observing witness testimony first-hand, and is, therefore, better positioned than this Chamber to assess the reliability and credibility of the evidence.

9. […] Where the convicted person is appealing, the Appeals Chamber will reverse only if it finds that no reasonable trier of fact could have made the particular finding of fact beyond reasonable doubt and the conviction relied on this finding. […]

128.    […] [T]he Chamber recalls that it is not conducting a trial de novo.[1]

[…]

137.    The Appeals Chamber notes at the outset that, in respect of alleged errors of fact, the burden of showing that the Trial Chamber’s findings were unreasonable is on Kayishema.  This standard of appellate review means that the “task of hearing, assessing and weighing the evidence presented at trial is left” to the Trial Chamber. Hence, the Appeals Chamber must give “a margin of deference” to factual findings reached by the Trial Chamber.[2]  One aspect of such burden is that it is up to the Appellant to draw the attention of the Appeals Chamber to the part of the record on appeal, which in his view supports the claim he is making.  From a practical standpoint, it is the responsibility of the Appellant to indicate clearly which particular evidentiary material he relies upon. Claims that are not supported by such precise references to the relevant parts of the record on appeal[3] will normally fail, on the ground that the Appellant has not discharged the applicable burden.

[…]

143.    […] As noted by ICTY Appeals Chamber, “two judges, both acting reasonably, can come to different conclusions on the basis of the same evidence”.[4] Accordingly, in his submissions, an appellant must not limit himself to proposing alternative conclusions that may have been open to the Trial Chamber on the basis of the evidence that was before it. In order for the Appeals Chamber to act, an appellant has to demonstrate that the particular findings made by the Trial Chamber were, in light of the evidence that was before it, unreasonable. […]

[…]

253.    […] The Chamber reiterates its position as regards the allegations of errors of fact and recalls that unless the Appellant shows the unreasonableness of the Chamber’s findings and the miscarriage of justice occasioned by the alleged errors, the Appeals Chamber does not find it necessary to review the trial judges’ findings established beyond reasonable doubt. […]

See also paras. 146, 237, 244, 255, 258, 295 and 320.

36.     Rule 115 (A) provides that a “party may apply by motion to present before the Appeals Chamber additional evidence which was not available to it at the trial”. That relates to appeals. Rule 119 enables a party to seek a review “[w]here a new fact has been discovered which was not known to the moving party at the time of the proceedings before a Trial Chamber or the Appeals Chamber, and could not have been discovered through the exercise of due diligence”. The Appellant submits that the reference to “diligence” in the latter but not in the former means that diligence is not required under Rule 115. However, whilst the Rules can illustrate the meaning of the Statute under which they are made, they cannot vary the Statute. If there is a variance, it is the Statute which prevails. But, for the reasons explained below, there is no variance in this case. In the view of the Appeals Chamber, there is a requirement for the exercise of due diligence by a party moving under Rule 115.

37.     Article 25, paragraph 1, of the Statute provides for appeals on two grounds, namely, “an error on a question of law invalidating the decision” and “an error of fact which has occasioned a miscarriage of justice”. The first error is clearly an error committed by the Trial Chamber. That, in principle, would seem to be also the case with the second error. But it is difficult to see how the Trial Chamber may be said to have committed an error of fact where the basis of the error lies in additional evidence which, through no fault of the Trial Chamber, was not presented to it. Where evidence was sought to be presented to the Trial Chamber but was wrongly excluded by it, there is no need for recourse to the provisions relating to the production of additional evidence to the Appeals Chamber; there the Trial Chamber would have committed an error appealable in the ordinary way.

38.     It is only by construing the reference to “an error of fact” as meaning objectively an incorrectness of fact disclosed by relevant material, whether or not erroneously excluded by the Trial Chamber, that additional material may be admitted. Such an extension of the concept of an “error of fact” as being not restricted to an error committed by the Trial Chamber may be required by justice; but justice would also require the accused to show why the additional evidence could not be presented to the Trial Chamber in exercise of the rights expressly given to him by the Statute. It would be right to hold that the purpose of the Statute in giving those rights was that the accused should exercise due diligence in utilising them. This would exclude cases in which the failure to exercise those rights was due to lack of diligence.

[…]

40.     The compulsory and protective machinery of the International Tribunal may not always be able to give total assurance that witnesses will be both available and protected if necessary. That is all the more reason why the machinery at the disposal of the International Tribunal should be used. A party seeking leave to present additional evidence should show that it has sought protection for witnesses from the Trial Chamber where appropriate, and that it has requested the Trial Chamber to utilise its powers to compel witnesses to testify if appropriate. Any difficulties, including those arising from intimidation or inability to locate witnesses, should be brought to the attention of the Trial Chamber.

[…]

42.     By the time proceedings have reached the Appeals Chamber, evidence relevant to the culpability of the accused has already been submitted to a Trial Chamber to enable it to reach a verdict and a sentence, if he is found guilty. From the judgement of the Trial Chamber there lies an appeal to the Appeals Chamber. The corrective nature of that procedure alone suggests that there is some limitation to any additional evidentiary material sought to be presented to the Appeals Chamber; otherwise, the unrestricted admission of such material would amount to a fresh trial. Further, additional evidence should not be admitted lightly at the appellate stage, considering that Rule 119 provides a remedy in circumstances in which new facts are discovered after the trial.

43.     Consideration may be given to the consequences of the opposite holding that additional evidence may be presented to the Appeals Chamber even where, through lack of diligence, it was not presented to the Trial Chamber though available. The Prosecutor can appeal from an acquittal. She may seek to reverse the acquittal on the basis of an error of fact disclosed by additional evidence. If the additional evidence was available to her but not presented to the Trial Chamber through lack of diligence, the accused is in effect being tried a second time. In substance, the non bis in idem prohibition is breached.

44.     The Appeals Chamber therefore finds that the position under the Statute is as indicated above and cannot be cut down by reference to any apparent discrepancy in the wording of Rules 115 and 119 of the Rules. The word “apparent” is used because, on a proper construction, Rule 115 is to be read in the light of the Statute; it is therefore subject to requirements of the Statute which have the effect of imposing a duty to be reasonably diligent. Where evidence is known to an accused person, but he fails through lack of diligence to secure it for the Trial Chamber to consider, he is of his own volition declining to make use of his entitlements under the Statute and of the machinery placed thereunder at his disposal; he certainly cannot complain of unfairness.

45.     In summary, additional evidence is not admissible under Rule 115 in the absence of a reasonable explanation as to why it was not available at trial. Such an explanation must include compliance with the requirement that the moving party exercised due diligence. This conclusion is consistent with the Statute and with the jurisprudence of many countries; it is not, however, dependent on that jurisprudence.

[…]

3.       Material which existed at trial but of which the Defence was unaware

[…]

58.     […] While the Defence is required to use due diligence to identify and seek out witnesses, there are limits to this obligation. The Appeals Chamber finds that the Appellant has provided sufficient indication that these witnesses and materials were unknown to the Defence, despite the exercise of due diligence, and thus not available at the time of trial […].

4.       Material which the Appellant was unable to adduce at trial

59.     This category relates to witnesses of whom the Defence was aware at the time of trial but whose evidence they were unable to produce. The material under this heading may be divided into three sub-categories: witnesses who were unwilling or unable to come forward at the trial stage, for example, witnesses who were imprisoned at the time; witnesses alleged to have been intimidated; and potential witnesses who could not be located at the time of trial.

60.     First, then, there is the category of potential witnesses who were simply unwilling to come forward at the trial stage but are now willing to do so at the appeal stage. […] No evidence has been submitted to the Appeals Chamber to indicate that any request was made to the Trial Chamber for the issue of subpoenas to compel the attendance of these witnesses. Despite the obvious practical difficulties in obtaining the evidence of such witnesses, a party cannot later seek to have such material admitted as additional evidence unavailable at trial unless it has raised the issue with the Trial Chamber at the time. As discussed above, the requirement of due diligence is not satisfied where there is insufficient attempt to invoke such coercive measures as were at the disposal of the International Tribunal. Therefore, it cannot be said that the evidence of these three witnesses was not available at trial.

[…]

62.     The second category is a substantial one. It relates to potential witnesses who were known to the Defence at the time of trial but who are said to have been intimidated by persons in authority in the former Yugoslavia. […] Again, in the absence of any evidence to demonstrate that attempts were made to obtain such protection for these witnesses as the International Tribunal could offer, the Appeals Chamber finds that reasonable diligence was not exercised. Consequently, the testimony of these witnesses cannot be said to have been unavailable at trial.

[RULE 115 OF THE ICTY RULES WAS SUBSEQUENTLY AMENDED ON 12 July 2002, 30 September 2002, and 21 July 2005]