This article analyzes two recent cases on the legality of security detentions in armed conflicts under the European Convention on Human Rights (ECHR). It will proceed as follows: First, it will identify competing interpretations of international humanitarian law and their implications for the way in which the relationship between international humanitarian law and human rights law can be approached. Second, the paper will analyze the decisions of both the High Court of Justice and the Court of Appeal in Serdar Mohammed, and of the European Court of Human Rights in Hassan. Third, the article will compare the approaches and analyze to what extent a reconciliation is possible. It will be demonstrated that the decisions in fact are to a great extent reconcilable. The article will conclude that the interpretations by the English courts and by the European Court of Human Rights are to commend, in particular because of a commonality they share: the awareness that legal orders cannot be treated as if they would stand in isolation from each other, and that their interrelationship can be properly assessed without merging them.