This article seeks to explore the reasons why sanctions for international humanitarian law (IHL) violations are so difficult to put into effect. Beyond the lack of willingness of states to do so for political reasons, some more technical aspects should be emphasized. The implementation of sanctions is too often seen solely through the prism of international law, without enough attention being paid to the complexity and diversity of municipal legal systems. The author puts forward the idea that efficiency starts with a clear sharing of competencies. Three main issues are discussed: first, the influence of the sharing of competencies within the state (between the judiciary, the executive and the legislature) on the implementation of sanctions; second, the broad interpretation of their powers by regional or international bodies in charge of monitoring and reviewing human rights protection; and, third, the creation of new or specific bodies in charge of dealing with and if necessary punishing gross violations of humanitarian law.