Operation Lifeline Sudan (OLS) seeks to integrate humanitarian principles and the protection of civilians within its mandate and operations. This paper details the ways in which these laws and principles were promoted through negotiation, advocacy, dissemination and training and the monitoring and follow-up of violations and abuses. It seeks to distill specific lessons from working with armed opposition movements, as distinct from sovereign governments, in particular the concern of humanitarian agencies that they may provide or be seen to provide legitimacy to those who mistreat their populations.