147. The Appeals Chamber recalls that the actus reus of aiding and abetting is constituted by acts or omissions specifically directed to assist, encourage, or lend moral support to the perpetration of a specific crime, and which have a substantial effect upon the perpetration of the crime.[1] The Appeals Chamber has explained that an individual can be found liable for aiding and abetting a crime when it is established that his conduct amounted to tacit approval and encouragement of the crime and that such conduct substantially contributed to the crime.[2] When this form of aiding and abetting has been a basis for a conviction, “it has been the authority of the accused combined with his presence on (or very near to) the crime scene, especially if considered with his prior conduct, which all together allow the conclusion that the accused’s conduct amounts to official sanction of the crime and thus substantially contributes to it.” [3]

149. With respect to Ndahimana’s arguments regarding the number of perpetrators involved, the Appeals Chamber notes that the Trial Chamber made no specific finding on the number of assailants on 16 April 1994, only concluding that “thousands of persons (assailants and refugees alike) were present” at Nyange Parish. Regardless of the number of assailants, the Appeals Chamber considers that the Trial Chamber was not required to establish that Ndahimana’s presence was noticed by or provided moral support to all perpetrators to find that he substantially contributed to the killings. As for Ndahimana’s argument that his assistance was not necessary as the assailants were already fully determined to commit the crimes at Nyange Church, the Appeals Chamber recalls that proof of a cause-effect relationship between the conduct of the aider and abettor and the commission of the crime, or proof that such conduct served as a condition precedent to the commission of the crime, is not required by law.

In footnote 526, the Appeals Chamber noted that:

[…] The Appeals Chamber also emphasises that, contrary to the Trial Chamber’s suggestion, Ndahimana’s contribution to the 16 April killings in the form of providing moral support by tacit approval is not to be characterised as an omission. See Trial Judgement, heading Section 4.3.2 and paras. 810, 811. See also Brđanin Appeal Judgement, para. 273; Ntagerura et al. Appeal Judgement, para. 338.

74. The Appeals Chamber recalls that “an aider and abettor carries out acts specifically directed to assist, encourage, or lend moral support to the perpetration of a certain specific crime, which have a substantial effect on the perpetration of the crime.”[1] The Appeals Chamber has explained that “[a]n accused can be convicted for aiding and abetting a crime when it is established that his conduct amounted to tacit approval and encouragement of the crime and that such conduct substantially contributed to the crime.”[2] Where this form of aiding and abetting has been a basis of a conviction, “it has been the authority of the accused combined with his presence on (or very near to) the crime scene, especially if considered together with his prior conduct, which all together allow the conclusion that the accused’s conduct amounts to official sanction of the crime and thus substantially contributes to it.”[3]

75. In view of Kalimanzira’s position as directeur de cabinet of the Ministry of Interior, it was reasonable for the Trial Chamber to determine that his silent presence during Ndayamabaje’s inflammatory speech would have offered tacit approval of its message. The basis of Kalimanzira’s conviction, however, rests on the Trial Chamber’s conclusion that Kalimanzira’s tacit approval not only sanctioned Ndayambaje’s message, but in fact substantially contributed to killings which occurred after the ceremony.[4]