This booklet draws together the lessons learned by the ICRC over the past few decades and aims to provide authorities and the most senior personnel among arms carriers with an overview of what we have come to call the “integration” process. This is the process of transposing legal rules into concrete mechanisms or measures to ensure compliance and adopting the means required to achieve this end. Integration is a continuous process. It must address doctrine, education, training and equipment issues and be backed up by an effective system of sanctions. The document is divided into three parts. The first presents the legal framework applicable to the use of force and the responsibilities of the highest political authorities regarding its implementation and dissemination. The second refers more specifically to arms carriers and addresses technical aspects related to integrating the relevant law into doctrine, education, training and equipment, plus the crucial role that sanctions play. The third part discusses the ICRC’s relationship with international law and the ways in which the organization can actively support efforts to promote lawful behaviour. The booklet refers mainly to States and their responsibilities. However, the process and the main concepts and conclusions can be extended by analogy to non-State armed groups that commit themselves to respecting the law and have the capacity to effectively discharge their responsibilities over time.