This article tries to imagine how the development of international humanitarian law (IHL) could continue despite current difficulties, increasing the ownership and contribution of States and armed groups in this process. After suggesting that some traditional assumptions about IHL may need to be abandoned, it tries to suggest a new way in which IHL rules could be developed, through States adopting together core obligations and principles and each State and armed group then specifying the details internally, but publicly. Finally, it stresses the importance and difficulties of involving non-State armed groups in this process.