This chapter explores the interaction between terrorism suppression and international humanitarian law in the context of domestic terrorism prosecutions. The chapter sketches the relevant terrorism suppression treaty regime and explores the possible interpretations which should be given to regime interaction clauses therein. In particular, this chapter argues that the interaction between terrorism suppression and international humanitarian law dictated by treaty results in both a floor and a ceiling on the exercise of domestic criminal jurisdiction – creating international law limitations on the right of State Parties to criminalise acts of war as ‘terrorism’.