This article cautions against the notion that the good intentions of European human rights law necessarily undermine international humanitarian law. In Al-Jedda, despite some suggestions to the contrary, the European Court did not misconstrue the law of belligerent occupation. The court erred, however, in assuming that the duty of non-detention under Article 5(1) of the European Convention can only be ‘displaced’ by a counter-duty of security detention. Whereas the law of belligerent occupation does not impose such a counter-duty, it does empower the occupation authorities to detain on security grounds, and exercising this power would frustrate observing Article 5(1) and vice versa. The norm conflict was soluble, but the would-be need to modify the scope and/or content of Article 5(1) or the law of belligerent occupation, rendered the European Court ill suited for the task. Nevertheless, the court’s ruling against the UK need not mean that European occupying powers suddenly have no choice but to kill rather than detain without charge (and risk lawsuits later) when countering security threats. On the contrary, the law of belligerent occupation helps the occupiers devise Al-Jedda-compliant detention regimes. The judgment’s repercussions are direr for the internment of prisoners of war.