On 22 February 2012, the Court of Appeal of England and Wales was called on to interpret the definition of the crime of terrorism as contained in the relevant United Kingdom (UK) legislation. When confronted with defence arguments grounded in international law, the Court denied that attacks by non-state armed groups against governmental armed forces in a non-international armed conflict may be exempted from being labelled as terrorist acts. The present article contests this assumption. The Court of Appeal of England and Wales could have interpreted the UK legislation in light of the current international legal framework on the definition of the crime of terrorism in times of armed conflict. In particular, some international conventions on terrorism binding on the UK establish that all attacks committed in the context of an armed conflict, including non-international armed conflicts, continue to be governed by international humanitarian law (IHL). IHL provides a definition of the crime of terrorism in times of armed conflict and the Court should have interpreted the UK domestic legislation consistently with this definition. Such an approach is also supported by the idea that non-state actors should be encouraged to apply rules of IHL. Marking them as terrorists, even when they abide by the laws of war, constitutes instead a disincentive to comply with such laws.