In the debate about the question if, when, and how humanitarian interventions can afford peace and justice, military action needs to be taken into consideration. To discuss the meaning of justice in relation to military intervention, conclusions can be drawn from a historical view of the bellum iustum topic, as treated by the Spanish scholars Sepúlveda, Vitoria and Las Casas. Historical analysis reveals the principles both for the ius ad bellum and the ius in bello, that can be found in a recent proposal, the report The Responsibility To Protect (2001) of the International Commission on Intervention and State Sovereignty (ICISS). In addition, for the recovery of justice, a ius post bellum for the prosecution of “crimes against humanity,” as intended by the International Criminal Court (ICC), seems important.