This chapter treats two fairly distinct, but at the same time related, topics since individual criminal responsibility is predicated on the recognition of a ius puniendi. The imposition of punishment is, in turn, predicated upon the determination of criminal responsibility. Thus, ius puniendi, responsibility and punishment are all interrelated elements of the (international) criminal justice process. The former element is a necessary, but not sufficient condition of the latter one, e.g., the ius puniendi is a necessary condition of responsibility and this, in turn, is a necessary condition of punishment. From a prosecution perspective, if everything goes according to plan the accused will be punished and the sentence enforced because his or her responsibility for the acts charged has been demonstrated beyond reasonable doubt.