Efforts to protect prisoners of war and individuals held by combatant forces have an elaborate architecture in the global order. Yet the situation has become increasingly distorted by the rising prominence of non-state actors (illegal combatants) in conflict. This chapter addresses this gray area in three stages: first, to survey the main aspects of the law of war, especially as it illumines the topic of prisoner and detainee status, and second to parse the particular issues surrounding the application of the law on war to prisoners and detainees. Last, attention will be paid to the challenge of Fourth Generation Warfare as it impacts on these contemporary matters.