The first step in determining the international legal framework(s) applicable to the detention activities of non-State armed groups (NSAGs) is to acknowledge how they are intuitively considered: non-State actors (NSAs). Inevitably, any attempt to examine what these entities are allowed to do, or rather are restricted from doing within the international realm, is met by challenges related to their limited legal ‘subjectivity’, how they acquire international obligations and the actual content of these rules. This is because this normative framework is a system which confers full legal personality to States, and much of its dynamics are devoted to protecting what one might call their ‘monopoly of subjecthood’. This chapter analyses the relevance of both international humanitarian law and international human rights law when dealing with NSAGs, identifying the various reasons that serve to justify such an examination. This exercise serves to locate NSAGs within the broad international legal architecture. In particular, it explores why and how these legal regimes relate to NSAGs, espousing the different views on their binding nature and advocating for an alternative view that considers their place within their international community.