One of the rudimentary propositions that is communicated at an early stage in the career of every aspiring criminologist is that the concept of ‘crime’ has no objective reality, but is an artificial construct of the criminal law. Implicitly, therefore, when the term ‘transnational organised crime’ is used, it conveys the message that a policy decision has been taken that the forms of behaviour that it embraces should be the subject of this type of legal regulation. However, it is not an implication that it is safe to draw because, distinct from any technical legal definition, the term also has a colloquial meaning which relies on everyday understanding. Rather like the proverbial joke about the elephant and the pillar-box, we may not be able to define what we mean by transnational organised crime, ‘but we recognise it when we see it’. It will be one of the principal arguments of this chapter, however, that the veneer of confidence which this appeal to common sense creates is potentially very unhelpful because it disguises the reality that the phenomenon of transnational organised crime poses considerable challenges for criminal law regulation. At first base, it is very unclear that everything to which the label is applied is in fact criminal, or that it should be. Consequently, the term is used in its colloquial sense throughout this chapter unless specifically stated otherwise. But even where there is a case for criminalisation in principle, questions arise as to which exact aspects of the behaviour involved should be the targets of offences. Moreover, these theoretical issues are not the only ones that are relevant. Separate from them, but having a significant practical bearing on their resolution, is a different type of difficulty from which the chapter’s second line of argument will be developed.