In international criminal law doctrine, a distinction is usually made between international crimes stricto sensu and transnational crimes. The first mentioned category covers the most heinous crimes and suspects can be exposed to the jurisdiction of international criminal courts and tribunals. Transnational crimes concern harmful activities, whose volatile nature constitutes a nuisance for national law enforcement. They are the subject of so-called ‘suppression conventions’ that instruct states to engage in closer cooperation in criminal matters. However, neither the dichotomy between the two categories, nor the choice for the most appropriate level of law enforcement is cast in stone. After an investigation into the relationship between the taxonomy of crimes and criminal law enforcement, the chapter concludes that the choice of the most adequate forum need not necessarily be defined by the nature of the crime – transnational or international.