During times of military occupation following an armed conflict it is not uncommon for the victors to implement mass detention programmes aimed both at providing security and bringing criminals to justice. International human rights regimes serve as overarching guidance for these programmes but are subject to broad interpretations, so it is often unclear what regulations or laws should inform day-to-day operations. Military and civilian lawyers may find themselves practising in a foreign jurisdiction for which they have no training or experience, let alone licensure. Law enforcement officers and military police are forced to adapt long-held practices to a new environment. Questions arise as to the rights that detained individuals possess, as these programmes frequently combine rules from different legal systems with no clear authoritative hierarchy. Attention is focused on the treatment of detained individuals with far less emphasis placed on their due process rights or other fundamental legal freedoms. This article examines one such instance, the US detention programme in Iraq, and highlights the numerous ethical and professional conflicts presented when members of one justice system are transplanted into another without proper preparation and background.