This chapter examines the distinguishing features of transnational criminal law. It begins by tracing the roots of transnational criminal law to the challenge raised by the growth of the perception that crimes that cross borders – transnational crimes – threaten state interests and have thus generated a global criminal justice power. It justifies applying this label and paying attention to this global criminal justice power by pointing out that it has been largely ignored by a legal academy preoccupied with the doctrinal development of international criminal law in a strict sense. After noting that the system is inherently plural and built around a preoccupation with transnational crime rather than any single point of legislative origin, it argues that transnational criminal law provides a lens to bring this activity into focus. It then proceeds to examine why states agree to suppress transnational crime and the importance of the role played by the so-called ‘transnational hook’. It points out that this hook is a relatively empty moral concept concerned only with state interest in regard to crime that may cross a border and affect that state. It examines the private nature of the crimes and the impact on domestic policy which lead to its dualistic international and domestic nature. It notes that rather than having an overall unified purpose these crimes reflect an incoherent set of purposes in regard to different activities and that in many cases these are the purposes of particular political communities. Finally, the chapter looks at why poor suppression of transnational crimes by states may make international criminal jurisdiction appear attractive, but points out that applying such a jurisdiction is difficult given the incoherent, particularist character of transnational criminal law.