• By committing the violation themselves personally or by ordering/directing others to commit it; or • By failing in the responsibilities that attach to leadership (command or superior responsibility, whether civilian or military). This applies equally to individuals belonging to States or to a non-State actor (NSA) that is a party to a conflict.58 Indeed such a relationship is a prerequisite: an individual may not commit an international humanitarian law violation, based on the responsibility of the State or another party to a conflict, unless he or she is a member of, or is acting on behalf of, a party to the armed conflict.59 As the above are also forms of participation in international crimes, their contours are taken up in the international crimes section immediately below. Keep in mind, however, that while all war crimes will be violations of international humanitarian law, not all international humanitarian law violations are war crimes. In addition, war crimes may be committed by any individual, irrespective of membership of a party to a conflict or the ability to trigger State responsibility. 3. Crimes under international law Where an investigation addresses international crimes, it must be cognizant of the legal framework but also of the types of evidence and information that may be used to demonstrate the various aspects of crimes. Criminal law differs from international human rights law and international humanitarian law not only in that it focuses primarily on individual responsibility,60 but because it requires proof of additional elements, namely a mental element (mens rea) and a “mode of liability”.61 International crimes differ from domestic crimes not only in terms of the applicable law, but also in the context in which they are committed. For example, an armed conflict is a necessary prerequisite for the commission of war crimes,62 and a “widespread or systematic attack on a civilian population” is necessary for crimes Ibid. See also Rule 139. See the ICRC’s Customary IHL Study, Rule 149, setting out four categories of individuals or groups that can engage the responsibility of a State. Note that such is not the case for war crimes. While they are generally accepted as certain violations of IHL, war crimes may be committed by any individual, irrespective of membership of a party to a conflict or the ability to trigger State responsibility, as mentioned above. 60 “Individual criminal responsibility” is the rubric under which persons have been found guilty and punished at the international level for criminal acts. There is jurisprudence and practice on the criminal responsibility of legal persons and entities, but such discussion is beyond the scope of this note. 61 As employed in this guidance, the term “mode of liability” describes the role the individual played vis-à-vis other perpetrators, if any, including whether they were in a position of authority over others committing crimes. 62 Another war crimes chapeau is that the crime had a “nexus” to the conflict, meaning that it “took place in the context of and was associated with” an armed conflict. See Rome Statute, Elements of Crimes, art. 8, War Crimes, Introduction, para. c. For more coverage on the nexus requirement, see annex I. 58 59 COLLECTING AND ANALYSING THE INFORMATION 33