45. In Vasiljević, the Appeals Chamber set out the actus reus and mens rea of aiding and abetting. It stated:

(i) The aider and abettor carries out acts specifically directed to assist, encourage or lend moral support to the perpetration of a certain specific crime (murder, extermination, rape, torture, wanton destruction of civilian property, etc.), and this support has a substantial effect upon the perpetration of the crime. […]

(ii) In the case of aiding and abetting, the requisite mental element is knowledge that the acts performed by the aider and abettor assist [in] the commission of the specific crime of the principal. […][1]

The Appeals Chamber considers that there are no reasons to depart from this definition.

46. In this case, the Trial Chamber, following the standard set out in Furundžija, held that the actus reus of aiding and abetting “consists of practical assistance, encouragement, or moral support which has a substantial effect on the perpetration of the crime.”[2] It further stated that the mens rea required is “the knowledge that these acts assist the commission of the offense.”[3] The Appeals Chamber considers that the Trial Chamber was correct in so holding.

47. The Trial Chamber further stated that the actus reus of aiding and abetting may be perpetrated through an omission, “provided this failure to act had a decisive effect on the commission of the crime and that it was coupled with the requisite mens rea.”[4]  It considered:

In this respect, the mere presence at the crime scene of a person with superior authority, such as a military commander, is a probative indication for determining whether that person encouraged or supported the perpetrators of the crime.[5]

The Appeals Chamber leaves open the possibility that in the circumstances of a given case, an omission may constitute the actus reus of aiding and abetting. 

48. The Trial Chamber in this case went on to state:

Proof that the conduct of the aider and abettor had a causal effect on the act of the principal perpetrator is not required. Furthermore, participation may occur before, during or after the act is committed and be geographically separated therefrom.[6]

The Appeals Chamber reiterates that one of the requirements of the actus reus of aiding and abetting is that the support of the aider and abettor has a substantial effect upon the perpetration of the crime.  In this regard, it agrees with the Trial Chamber 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.  It further agrees that the actus reus of aiding and abetting a crime may occur before, during, or after the principal crime has been perpetrated, and that the location at which the actus reus takes place may be removed from the location of the principal crime.

49. In relation to the mens rea of an aider and abettor, the Trial Chamber held that “in addition to knowledge that his acts assist the commission of the crime, the aider and abettor needs to have intended to provide assistance, or as a minimum, accepted that such assistance would be a possible and foreseeable consequence of his conduct.”[7] However, as previously stated in the Vasiljević Appeal Judgement, knowledge on the part of the aider and abettor that his acts assist in the commission of the principal perpetrator’s crime suffices for the mens rea requirement of this mode of participation.[8] In this respect, the Trial Chamber erred.

50. The Trial Chamber agreed with the statement in the Furundžija Trial Judgement that “it is not necessary that the aider and abettor…know the precise crime that was intended and which in the event was committed. If he is aware that one of a number of crimes will probably be committed, and one of those crimes is in fact committed, he has intended to facilitate the commission of that crime, and is guilty as an aider and abettor.”[9] The Appeals Chamber concurs with this conclusion.

126. In relation to the mens rea applicable to crimes against humanity, the Appeals Chamber reiterates its case law pursuant to which knowledge on the part of the accused that there is an attack on the civilian population, as well as knowledge that his act is part thereof, is required.[1] The Trial Chamber, in stating that it “suffices that he knowingly took the risk of participating in the implementation of the ideology, policy or plan,” did not correctly articulate the mens rea applicable to crimes against humanity. Moreover, as stated above, there is no legal requirement of a plan or policy, and the Trial Chamber’s statement is misleading in this regard. Furthermore, the Appeals Chamber considers that evidence of knowledge on the part of the accused depends on the facts of a particular case; as a result, the manner in which this legal element may be proved may vary from case to case. Therefore, the Appeals Chamber declines to set out a list of evidentiary elements which, if proved, would establish the requisite knowledge on the part of the accused.

See also para. 127.

109. Before determining the scope of the term “civilian population,” the Appeals Chamber deems it necessary to rectify the Trial Chamber’s statement, contained in paragraph 180 of the Trial Judgement, according to which “[t]argeting civilians or civilian property is an offence when not justified by military necessity.” The Appeals Chamber underscores that there is an absolute prohibition on the targeting of civilians in customary international law.

110. In determining the scope of the term “civilian population,” the Appeals Chamber recalls its obligation to ascertain the state of customary law in force at the time the crimes were committed.[1] In this regard, it notes that the Report of the Secretary General states that the Geneva Conventions “constitute rules of international humanitarian law and provide the core of the customary law applicable in international armed conflicts.”[2] Article 50 of Additional Protocol I to the Geneva Conventions contains a definition of civilians and civilian populations, and the provisions in this article may largely be viewed as reflecting customary law. As a result, they are relevant to the consideration at issue under Article 5 of the Statute, concerning crimes against humanity.

111. Article 50, paragraph 1, of Additional Protocol I states that a civilian is “any person who does not belong to one of the categories of persons referred to in Article 4A(1), (2), (3) and (6) of the Third Convention and in Article 43 of this Protocol. In case of doubt whether a person is a civilian, that person shall be considered to be a civilian.” The Appeals Chamber notes that the imperative “in case of doubt” is limited to the expected conduct of a member of the military. However, when the latter’s criminal responsibility is at issue, the burden of proof as to whether a person is a civilian rests on the Prosecution.

113. Read together, Article 50 of Additional Protocol I and Article 4A of the Third Geneva Convention establish that members of the armed forces, and members of militias or volunteer corps forming part of such armed forces, cannot claim civilian status. Neither can members of organized resistance groups, provided that they are commanded by a person responsible for his subordinates, that they have a fixed distinctive sign recognizable at a distance, that they carry arms openly, and that they conduct their operations in accordance with the laws and customs of war. However, the Appeals Chamber considers that the presence within a population of members of resistance groups, or former combatants, who have laid down their arms, does not alter its civilian characteristic.[3] The Trial Chamber was correct in this regard.

114. However, the Trial Chamber’s view that the specific situation of the victim at the time the crimes were committed must be taken into account in determining his standing as a civilian may be misleading. The ICRC Commentary is instructive on this point and states:

All members of the armed forces are combatants, and only members of the armed forces are combatants. This should therefore dispense with the concept of quasi-combatants, which has sometimes been used on the basis of activities related more or less directly with the war effort. Similarly, any concept of a part-time status, a semi-civilian, semi-military status, soldier by night and peaceful citizen by day, also disappears. A civilian who is incorporated in an armed organization such as that mentioned in paragraph 1, becomes a member of the military and a combatant throughout the duration of the hostilities (or in any case, until he is permanently demobilized by the responsible command referred to in paragraph 1), whether or not he is in combat, or for the time being armed. If he is wounded, sick or shipwrecked, he is entitled to the protection of the First and Second Conventions (Article 44, paragraph 8), and, if he is captured, he is entitled to the protection of the Third Convention (Article 44, paragraph 1).[4]

As a result, the specific situation of the victim at the time the crimes are committed may not be determinative of his civilian or non-civilian status. If he is indeed a member of an armed organization, the fact that he is not armed or in combat at the time of the commission of crimes, does not accord him civilian status.

115. The Trial Chamber also stated that the “presence of soldiers within an intentionally targeted civilian population does not alter the civilian nature of that population.” The ICRC Commentary on this point states:

…in wartime conditions it is inevitable that individuals belonging to the category of combatants become intermingled with the civilian population, for example, soldiers on leave visiting their families. However, provided that these are not regular units with fairly large numbers, this does not in any way change the civilian character of a population.[5]

Thus, in order to determine whether the presence of soldiers within a civilian population deprives the population of its civilian character, the number of soldiers, as well as whether they are on leave, must be examined.

593. The first issue for the Appeals Chamber to determine is whether international law criminalises the use of detainees to dig trenches of a military character per se because it necessarily constitutes cruel treatment. As regards the employment of civilians for such purposes, Article 51 of Geneva Convention IV, governing the treatment of civilians,[1] precludes the ‘Occupying Power’ from compelling ‘protected persons’ to serve in its armed or auxiliary forces.[2] The Occupying Power may in fact compel protected persons to work if they are over eighteen years of age, and subject to certain other conditions.[3] ‘Protected persons’ may not, however, be compelled to undertake any work which would involve them in the obligation to take part in military operations, and in no case shall the requisition of labour lead to a mobilization of workers “in an organisation of a military or semi-military character.”[4]

597. The Appeals Chamber has noted that the use of forced labour is not always unlawful.[5] Nevertheless, the treatment of non-combatant detainees may be considered cruel where, together with the other requisite elements, that treatment causes serious mental or physical suffering or injury or constitutes a serious attack on human dignity. The Appeals Chamber notes that Geneva Conventions III and IV require that when non-combatants are used for forced labour, their labour may not be connected with war operations[6] or have a military character or purpose.[7] The Appeals Chamber finds that the use of persons taking no active part in hostilities to prepare military fortifications for use in operations and against the forces with whom those persons identify or sympathise is a serious attack on human dignity and causes serious mental (and depending on the circumstances physical) suffering or injury. Any order to compel protected persons to dig trenches or to prepare other forms of military installations, in particular when such persons are ordered to do so against their own forces in an armed conflict, constitutes cruel treatment. The Appeals Chamber accordingly finds that a reasonable trier of fact could have come to the conclusion that the Appellant has violated the laws or customs of war under Article 3 of the Statute, and common Article 3(1)(a) of the Geneva Conventions, and is guilty under Count 16 for ordering the use of detainees to dig trenches.

32. […] The issue which the Appeals Chamber will address is whether a standard of mens rea that is lower than direct intent may apply in relation to ordering under Article 7(1) of the Statute, and if so, how it should be defined.

41. Having examined the approaches of national systems as well as International Tribunal precedents, the Appeals Chamber considers that none of the Trial Chamber’s above articulations of the mens rea for ordering under Article 7(1) of the Statute, in relation to a culpable mental state that is lower than direct intent, is correct. The knowledge of any kind of risk, however low, does not suffice for the imposition of criminal responsibility for serious violations of international humanitarian law. The Trial Chamber does not specify what degree of risk must be proven. Indeed, it appears that under the Trial Chamber’s standard, any military commander who issues an order would be criminally responsible, because there is always a possibility that violations could occur. The Appeals Chamber considers that an awareness of a higher likelihood of risk and a volitional element must be incorporated in the legal standard.

42. The Appeals Chamber therefore holds that a person who orders an act or omission with the awareness of the substantial likelihood that a crime will be committed in the execution of that order, has the requisite mens rea for establishing liability under Article 7(1) pursuant to ordering. Ordering with such awareness has to be regarded as accepting that crime.[1]

See also para. 345 et seq.

62. The Appeals Chamber considers that the Čelebići Appeal Judgement has settled the issue of the interpretation of the standard of “had reason to know.” In that judgement, the Appeals Chamber stated that “a superior will be criminally responsible through the principles of superior responsibility only if information was available to him which would have put him on notice of offences committed by subordinates.”[1] Further, the Appeals Chamber stated that “[n]eglect of a duty to acquire such knowledge, however, does not feature in the provision [Article 7(3)] as a separate offence, and a superior is not therefore liable under the provision for such failures but only for failing to take necessary and reasonable measures to prevent or to punish.”[2] There is no reason for the Appeals Chamber to depart from that position.[3] The Trial Judgement’s interpretation of the standard is not consistent with the jurisprudence of the Appeals Chamber in this regard and must be corrected accordingly.

83. […] Disciplinary or penal action can only be initiated after a violation is discovered, and a violator is one who has already violated a rule of law. Further, it is illogical to argue both that “a superior’s responsibility for the failure to punish is construed as a sub-category of his liability for failing to prevent the commission of unlawful acts,” and that “failure to punish only led to the imposition of criminal responsibility if it resulted in a failure to prevent the commission of future crimes.”[1] The failure to punish and failure to prevent involve different crimes committed at different times: the failure to punish concerns past crimes committed by subordinates, whereas the failure to prevent concerns future crimes of subordinates.

85. In the view of the Appeals Chamber, the Trial Chamber did not err in finding to the effect that the responsibility of a commander for his failure to punish was recognised in customary law prior to the commission of crimes relevant to the Indictment. […]

148. The prohibition against pillage may therefore be considered to be part of customary international law. In addition, it may be noted that the Nuremberg Charter[1] and Control Council Law No. 10[2] prohibited the war crime of “plunder of public and private property,” and the crime of pillage was the subject of criminal proceedings before the International Military Tribunal at Nuremberg and other trials following the Second World War, where in certain cases, it was charged both as a war crime and a crime against humanity.[3] There may be some doubt, however, as to whether acts of plunder, in and of themselves, may rise to the level of gravity required for crimes against humanity.[4]

149. The Appeals Chamber finds that the destruction of property, depending on the nature and extent of the destruction, may constitute a crime of persecutions of equal gravity to other crimes listed in Article 5 of the Statute.

151. The Appeals Chamber notes that the Trial Chamber appears to use the terms deportation and forcible transfer interchangeably. The Geneva Conventions prohibit forcible transfers and deportation. Article 49 of Geneva Convention IV provides that “[i]ndividual or mass forcible transfers, as well as deportations of protected persons from occupied territory to the territory of the Occupying Power or to that of any other country, occupied or not, are prohibited, regardless of their motive.” Article 147 of Geneva Convention IV, listing grave breaches to which Article 146 relates, refers to “unlawful deportation or transfer or unlawful confinement of a protected person.” Article 85 of Additional Protocol I prohibits “the transfer by the occupying Power of parts of its own civilian population into the territory it occupies, or the deportation or transfer of all or part of the population of the occupied territory within or outside this territory in violation of Article 49 of the Fourth Convention.” In addition, Article 17 of Additional Protocol II provides:

1. The displacement of the civilian population shall not be ordered for reasons related to the conflict unless the security of the civilians involved or imperative military reasons so demand. Should such displacements have to be carried out, all possible measures shall be taken in order that the civilian population may be received under satisfactory conditions of shelter, hygiene, health, safety and nutrition.

2. Civilians shall not be compelled to leave their own territory for reasons connected with the conflict.

152. The Appeals Chamber in the Krnojelac case held that:

 Forcible displacements, taken separately or cumulatively, can constitute a crime of persecution of equal gravity to other crimes listed in Article 5 of the Statute. […]

The Appeals Chamber concludes that displacements within a state or across a national border, for reasons not permitted under international law, are crimes punishable under customary international law, and these acts, if committed with the requisite discriminatory intent, constitute the crime of persecution under Article 5(h) of the Statute.[1]

153. In light of the foregoing analysis and jurisprudence, the Appeals Chamber considers that at the time relevant to the Indictment in this case, deportation, forcible transfer, and forcible displacement constituted crimes of equal gravity to other crimes listed in Article 5 of the Statute and therefore could amount to persecutions as a crime against humanity.

53. The words “as such,” [in Article 2(2) of the ICTR Statute] however, constitute an important element of genocide, the “crime of crimes.”[1] It was deliberately included by the authors of the Genocide Convention in order to reconcile the two diverging approaches in favour of and against including a motivational component as an additional element of the crime. The term “as such” has the effet utile of drawing a clear distinction between mass murder and crimes in which the perpetrator targets a specific group because of its nationality, race, ethnicity or religion.[2] In other words, the term “as such” clarifies the specific intent requirement. It does not prohibit a conviction for genocide in a case in which the perpetrator was also driven by other motivations that are legally irrelevant in this context. Thus the Trial Chamber was correct in interpreting “as such” to mean that the proscribed acts were committed against the victims because of their membership in the protected group, but not solely because of such membership.

See also paragraphs 49–52.