This article analyses the experiences of the International Committee of the Red Cross (ICRC) in Colombia, and has two main purposes: first, to elaborate on the relationship between international humanitarian law (IHL) and the practical work of the ICRC in internal armed conflict; and second, to use our enhanced understanding of that relationship to shed light on important questions regarding the nature and effectiveness of IHL with respect to non-State armed groups. It proceeds in three main parts. First, it provides background on the work of the ICRC to contextualise the subsequent analysis, establishing the importance of IHL in the work of the ICRC in general. Second, it shows that for the ICRC, IHL is a means to an end (namely protection) rather than an end in itself, and that it is not the only (or even necessarily the primary) means to that end. Third, it argues that the ICRC often finds that reference to IHL is counter-productive to achieving desired protection outcomes, and that this calls into question the adequacy and effectiveness of the IHL framework itself. Finally, it concludes by suggesting why the existing framework may be less than optimal for achieving its aims, and how future research could contribute to a more comprehensive assessment of the appropriateness and adequacy of existing IHL.