International law, on the whole, deals with states. International humanitarian law (IHL), on the other hand, not only imposes duties on states, but also grants certain people (in particular, but not only, ‘protected persons’ in the Geneva Conventions sense) rights. IHL is not unique in this regard, the law of human rights, for example does the same. IHL, though, also imposes obligations on individuals, and, in certain cases, directly criminalises their violation. This is something international law rarely does. This chapter investigates the development of this phenomenon, the conditions under which violations of IHL become criminalised and a principle of responsibility that is directly linked to IHL – command responsibility.