1932. The Appeals Chamber now turns to the second implicit legal finding on the duty to punish, namely whether measures that would ordinarily be considered insufficient to fulfill the duty to punish might in certain circumstances be considered as the only necessary and reasonable measures available. The Appeals Chamber affirms that what constitutes “necessary and reasonable” measures to fulfil a commander’s duty is not a matter of substantive law but of evidence.[1] This means that the assessment of measures taken, in view of the material ability of the superior, must be evaluated on a case-by-case basis.[2] That being said, the Tribunal’s case law has established a minimum standard for measures that may fulfil the duty to punish. A trial chamber must look at what steps were taken to secure an adequate investigation capable of leading to the criminal prosecution of the perpetrators.[3] In this respect, it is well accepted that a superior’s duty to punish the perpetrators of a crime includes at least an obligation to investigate possible crimes, to establish the facts, and if the superior has no power to sanction, to report them to the competent authorities.[4] In respect of merely reporting crimes, this would only suffice to fulfil the duty to punish if such a report is likely to trigger an investigation or initiate disciplinary or criminal proceedings.[5] The Appeals Chamber notes that the duty of commanders to report to competent authorities is specifically provided for under Article 87(1) of Additional Protocol I, and that the duty may also be deduced from the provision of Article 86(2) of Additional Protocol I.[6] In addition, Article 87(3) of Additional Protocol I specifies that where a commander is aware that his subordinates have committed breaches of the Conventions or the Protocol, he must “initiate disciplinary or penal action against violators thereof”. While these provisions indicate that the report by a commander must be made to a body tasked with investigation and punishment, in military practice such reports may sometimes be made either directly to the competent authorities or through a superior officer.[7] The crucial point is that in order to constitute a necessary and reasonable measure to punish, the commander’s report must be sufficient to trigger the action of the competent authorities.

1933. As indicated by the above, a particular measure can only be regarded as necessary and reasonable where it has been shown to be capable of contributing to investigating or punishing the crimes in the circumstances which prevailed at the time. This is so even if the result ultimately falls short of punishment.[8] […]

1938. […] The Appeals Chamber considers that a duty to punish is not fulfilled where a commander was content to rely on assurances which he knew would not be or were not being implemented.[9] […]

1898. […] [T]here is no minimum number of subordinates that are required to be involved in the commission of crimes in order to trigger a commander’s responsibility. […]

134. The Appeals Chamber recalls that a trial chamber has the discretion to rely upon evidence of accomplice witnesses. However, when weighing the probative value of such evidence, the trial chamber is bound to carefully consider the totality of the circumstances in which it was tendered. In particular, consideration should be given to circumstances showing that accomplice witnesses may have motives or incentives to implicate the accused person before the Tribunal or to lie.[1] The Appeals Chamber also recalls that evidence of witnesses who might have motives or incentives to implicate the accused is not per se unreliable, especially where such a witness may be thoroughly cross-examined; therefore, reliance upon this evidence does not, as such, constitute an error of law.[2] However, a trial chamber must explain the reasons for accepting the evidence of such a witness.[3] Particularly relevant factors for the assessment of accomplice witnesses’ credibility include:

the extent to which discrepancies in the testimony were explained; whether the accomplice witness has made a plea agreement with the Prosecution; whether he has already been tried and, if applicable, sentenced for his own crimes or is still awaiting the completion of his trial; and whether the witness may have any other reason for holding a grudge against the accused.[4]

135. A trial chamber’s discretion to rely on uncorroborated, but otherwise credible, witness testimony applies equally to the evidence of witnesses who may have motive to implicate the accused, provided that appropriate caution is exercised in the evaluation of their testimonies.[5]

131. The Appeals Chamber recalls that a trial chamber is best placed to assess the credibility of a witness and reliability of the evidence adduced,[1] and therefore has broad discretion in assessing the appropriate weight and credibility to be accorded to the testimony of a witness.[2] Indeed, the ICTR Appeals Chamber has previously noted that it “is loathe to disturb such credibility assessments”.[3] As with other discretionary decisions, the question before the Appeals Chamber is not whether it “agrees with that decision” but “whether the trial chamber has correctly exercised its discretion in reaching that decision”.[4] The party challenging a discretionary decision by the trial chamber must demonstrate that the trial chamber has committed a discernible error. The Appeals Chamber will only overturn a trial chamber’s discretionary decision where it is found to be: (1) based on an incorrect interpretation of governing law; (2) based on a patently incorrect conclusion of fact; or (3) so unfair or unreasonable as to constitute an abuse of discretion.[5] In such cases the Appeals Chamber will deem that the witness evidence relied on by the Trial Chamber could not have been accepted by any reasonable tribunal of fact or that the evaluation of the evidence was “wholly erroneous”, and proceed to substitute its own finding for that of the Trial Chamber.[6]

132. The Appeals Chamber is mindful that when exercising its broad discretion, a trial chamber has to consider relevant factors on a case-by-case basis, including the witness’s demeanour in court; his role in the events in question; the plausibility and clarity of his testimony; whether there are contradictions or inconsistencies in his successive statements or between his testimony and other evidence; any prior examples of false testimony; any motivation to lie; and the witness’s responses during cross-examination.[7] The Appeals Chamber recalls that the many potential factors relevant to the trial chamber’s assessment of a witness’s credibility include corroboration,[8] the witness’s close personal relationship to an accused,[9] and the witness’s criminal history.[10] The application of these factors, and the positive or negative impact they may have on the witness’s credibility, varies according to the specific circumstances of each case.[11] Finally, a trial chamber can reasonably accept certain parts of a witness’s testimony and reject others.[12]

133. The Appeals Chamber recalls that a trial chamber is not required to set out in detail why it accepted or rejected a particular testimony,[13] and that an accused’s right to a reasoned opinion does not ordinarily demand a detailed analysis of the credibility of particular witnesses.[14] However, a trial chamber must provide reasons for accepting testimony despite alleged or material inconsistencies when it is the principal evidence relied upon to convict an accused.[15]

[…]

136. The Appeals Chamber recalls that it is not an error of law per se to accept and rely on evidence that is inconsistent with a prior statement or other evidence adduced at trial.[16] A trial chamber has the discretion to accept a witness’s evidence, notwithstanding inconsistencies between the said evidence and his previous statements.[17] However, a trial chamber must take into account any explanations offered for such inconsistencies when determining the probative value of the evidence.[18]

137. Similarly, a trial chamber has the discretion to evaluate any inconsistencies that may arise within or among witnesses’ testimonies and to determine whether, in the light of the overall evidence, the witnesses were reliable and credible.[19] Considering that minor inconsistencies commonly occur in witness testimony without rendering it unreliable, it is within the discretion of a trial chamber to evaluate discrepancies and to consider the credibility of the evidence as a whole, without explaining its decision in every detail.[20]

343. The Appeals Chamber recalls that an alibi does not constitute a defence in its proper sense.[1] Where an accused raises an alibi he is merely denying that he was in a position to commit the crime with which he was charged.[2] It is settled jurisprudence of both the ICTY and the ICTR that an accused does not bear the burden of proof beyond reasonable doubt in relation to establishing an alibi[3] but only needs to produce evidence likely to raise a reasonable doubt in the Prosecution’s case.[4] If the alibi is reasonably possibly true, it must be accepted.[5] Where the alibi evidence does prima facie account for the accused’s activities at the relevant time of the commission of the crime, the onus remains on the Prosecution to eliminate any reasonable possibility that the alibi is true.[6] The Prosecution must establish beyond reasonable doubt that, despite the alibi, the facts alleged are nevertheless true.[7]

1952. The Appeals Chamber notes that Rule 73 of the Rules allows a party to move before a chamber by way of a motion for an appropriate ruling or relief and introduces the procedure for requesting certification to file an interlocutory appeal after a decision on a motion is rendered. Although its wording is not entirely explicit in this regard, Rule 73 of the Rules should be understood as imposing a duty on a chamber to render an order or decision on every validly filed motion, even if the motion is considered frivolous or an abuse of process.[1] This duty ensures that an accused can exercise his or her right of appeal and take such actions as provided for by Rule 73(C) of the Rules. […] A motion which can be considered as being rendered moot by subsequent actions still remains within the jurisdiction of a trial chamber to consider. […]

2038. The Appeals Chamber recalls that prolonged and systematic involvement in criminal conduct may be considered as an aggravating circumstance.[1] […]

1765. […] [T]he Appeals Chamber observes that the participation of the aider and abettor need not be a crime in itself.[1] […]

12.     The Appeals Chamber is also not persuaded that Ntabakuze’s potential ground of review in relation to the IAMSEA killings satisfies the requirements for the assignment of an investigator and counsel at the expense of the Mechanism. The Appeals Chamber notes that this is the first time that Ntabakuze specifically raises the argument that the Para-Commando soldiers who were involved in the crimes at IAMSEA might have been under the control of another battalion, and specifically that in March 1994 they might have been reassigned to the Presidential Guard.[1] However, the issue of whether Ntabakuze had effective control over the Para-Commando soldiers who participated in the killings was litigated both at trial and on appeal.[2] Ntabakuze’s intention to pursue additional evidence in relation to the alleged presence of the Presidential Guard in the vicinity of IAMSEA and the possibility that the Para-Commando soldiers involved in the crimes might have been under the Presidential Guard’s command,[3] does not appear to constitute a “new fact” that may have a chance of success on review.

194.     The evolving nature of ongoing investigations and the reality of a party’s possession of incomplete information at certain stages of trial proceedings might excuse the provision of an incomplete initial notice of alibi or justify subsequent supplemental filings.[1] However, […].

195.     As a result, the Appeals Chamber considers that the Trial Chamber reasonably questioned the circumstances surrounding the belated advancement of Ngirabatware’s alibi. The manner in which an alibi is presented may impact its credibility.[2] This is the case even if the Prosecution ultimately had an opportunity to interview the potential alibi witnesses or call additional evidence to rebut the alibi. A trial chamber is not required to consider whether the Prosecution suffered prejudice from the delayed filing of the notice of alibi.[3] Therefore, it was within the Trial Chamber’s discretion to take into account Ngirabatware’s failure to provide adequate and timely notice in assessing his alibi in connection with the events occurring on 7 April 1994.