What does the law of armed conflict say about detention in non-international armed conflict? Is the law “utterly silent,” as some contend, with respect to the grounds for detention—regulating who may be confined and for what status or behavior? And do the in bello rules provide a source of affirmative authority that empowers belligerents to engage in detention? How those questions are resolved and, in particular, the basis for reaching the conclusions may have unintended consequences for the regulation of warfare. This article contends that the laws of war regulate the grounds for detention but do not authorize detention in non-international armed conflict. The article suggests some of the perverse effects of recent decisions by national and international bodies which, according to the author, may have reached the right result but for the wrong reasons.