Momir Nikolić argued that the Trial Chamber is not allowed to substitute the Prosecution’s assessment of his co-operation with its own. The Prosecution submitted that Momir Nikolić had co-operated fully; the Trial Chamber had some reservations.

On the law, the Appeals Chamber disagreed with Momir Nikolić’s claim. It held: “The Appeals Chamber acknowledges that the Prosecution is in a position to accurately assess the co-operation of an accused. However, the evaluation of the extent and nature of the Appellant’s co-operation, and thus the weight, if any, to be given to this mitigating circumstance, is within the discretion of the Trial Chamber.” (para. 91).

However, the Appeals Chamber also held that if the Trial Chamber does not accept the evaluation of the Prosecution regarding the accused’s co-operation, it has to give sufficient reason why it does so, because of its obligation to provide a reasoned opinion under Article 23(2) of the Statute (para. 96). The Appeals Chamber therefore looked at whether the Trial Chamber gave sufficient reasons for its reservations regarding Momir Nikolić’s co-operation with the Prosecution.

The Appeals Chamber found several errors: the Trial Chamber stated that there were “numerous instances” where Momir Nikolić had been evasive in his testimony, but cited only to one such instance (para. 103); the Trial Chamber stated that he had told lies to the Prosecution before entering a plea agreement, but disregarded the fact that Momir Nikolić went back to the Prosecution on his own initiative, apologised, corrected his statement, and openly admitted to having rendered false confessions (para. 107); the Trial Chamber stated that Momir Nikolić’s testimony was not very detailed and that he should generally have been more open, but it had never asked for more details and it did not cite to any instance where the accused had failed to be more detailed or open (para. 113).

The Appeals Chamber concluded that these errors led the Trial Chamber to attach insufficient weight to the mitigating circumstance of his co-operation with the Prosecution (para. 114). 

8. The Appeals Chamber is of the view that the Prosecution’s argument that, as a matter of discretion, an accused person should not be released until the Prosecution has been able to interview him fully is misconceived.[1]  An accused person is not, while in the custody of the International Tribunal, at the disposal of the Prosecution.  An accused person may, if he decides to do so, co-operate with the Office of the Prosecutor, inter alia, by accepting to be interviewed by the Prosecution, but he does not have to do so and his provisional release is not conditioned, all other conditions being met, upon his giving such an interview while still in custody.

At para. 16, the Appeals Chamber recalled the case-law in that respect:

16. [T]he Appeals Chamber notes that an accused may, if he decides to do so, cooperate with the OTP, inter alia, by accepting to be interviewed by the Prosecution, but he does not have to do so and his provisional release is not conditioned, all other conditions being met, upon his agreement to be interviewed.[1] Against this backdrop the Appeals Chamber recalls that it has previously held that when an accused person decides to cooperate with the Prosecution, this matter may weigh in his favour when he seeks to be provisionally released, insofar as it shows his general attitude of cooperation towards the International Tribunal which is relevant to the issue that he will appear for trial.[2] However, an accused will not be penalised because he declines to cooperate with the Prosecution.[3] 

It then recalled the law applicable to assess an accused’s cooperation:

17. The Appeals Chamber recalls that the cooperation of an accused should not be assessed solely by reference to the value of the information the accused provides.[4] This is because an accused before this International Tribunal is not obliged to assist the Prosecution in proving its case and any evidence of willingness on the part of an accused to be voluntarily interviewed by the Prosecution is evidence of a degree of cooperation that an accused is entitled to withhold without adverse inference being drawn.[5]

In light of the confidential nature of the use made of the information provided by the Appellant, the Appeals Chamber considered that, “where the Trial Chamber must evaluate an accused’s cooperation based on information solely in the possession of the Prosecution”, it must be established “whether the Trial Chamber has sufficiently assessed the evidence provided on an ex parte basis in order to protect the rights of the accused, where the accused himself does not have the opportunity to do so”. See para. 56.

The Appeals Chamber then detailed the practice to be followed by the Prosecution and the Trial Chambers in such cases:

57. […] the better practice is to first check whether the documents in question could be disclosed inter partes in order to allow the accused to himself comment on the Prosecution’s submissions.[1] This may in certain instances necessitate an application to another Chamber for a variation in protective measures. Where it is not possible for such documents to be submitted inter partes, it is within a Trial Chamber’s discretion to rely on the Prosecution’s ex parte assessment of the accused’s cooperation, as the Trial Chamber did in the instant case. In this event, the Appeals Chamber emphasises that the Prosecution must provide sufficient explanations in its assessment as to why it considers the information given by an accused valuable or not. The Trial Chamber should then evaluate the nature and extent of the accused’s cooperation and set out a reasoned opinion in writing.[2] Under the circumstances, such reasoned opinion is the Appellant’s only guide as to whether his right to a fair trial has been preserved.

61. […] The Appeals Chamber refers in this context to the approach taken in the Dragan Nikolić case, where the Trial Chamber requested the Prosecution at the Sentencing Hearing to provide documents that “would enable [it] to review them in camera in order to assess if the Accused’s co-operation with the Prosecution could be regarded as being substantial”. The Trial Chamber then gave a substantive account of its analysis of the provided documents, before concluding that it could not itself assess them and therefore accepting the Prosecution’s assessment that the Accused’s co-operation was substantial.

62. The Appeals Chamber is convinced that, in order to provide a transparent assessment of the Appellant’s cooperation, a similar approach would have been appropriate in the present case, in particular in light of the reassurances given to the Appellant at the Sentencing Hearing.

66. The weight to be attached to co-operation as a mitigating factor is within the discretion of Trial Chambers, which can decide, after assessing the importance to give to this factor, to give it no weight, to give it “substantial” weight within the meaning of Rule 101(B)(ii), or to give it more “modest” weight in mitigation.[1] The Appellant in the present case only argues that the evidence clearly and unambiguously showed that his cooperation was substantial, and that this, combined with the risk to which he exposed himself by co-operating, should have led the Trial Chamber to accord “greater weight than merely ‘some importance’”.[2]  In the absence of a demonstration that the Trial Chamber committed an error in assessing the importance of his cooperation, the Appeals Chamber dismisses the Appellant’s argument in that regard.