Until December 2000, the term “trafficking” was not defined in international law, despite its incorporation in a number of international legal agreements. The long-standing failure to develop an agreed-upon understanding reflected major differences of opinion concerning the ultimate end result of trafficking, its constitutive acts, and their relative significance, as well as the similarities and differences between trafficking and related issues such as illegal migration and migrant smuggling. It is no coincidence that the various definitions proposed and adopted throughout the twentieth century inevitably mirrored the interests, priorities, and perspectives of their promoters. Only in the late 1990s, when attempts were made to deconstruct understandings about trafficking in order to develop an agreed-upon international definition, were the extent and depth of divisions in both perceptions and priorities revealed.

This chapter commences with an overview of how trafficking was used and evolved as a legal concept throughout the twentieth century. Particular attention will be given to the final decade of that century, when efforts to develop an internationally agreed definition commenced in earnest. It was during this period that many of the most difficult questions were first raised. For example, does “trafficking” cover only the action (recruitment and transport) aspect, or does it also encompass the outcome of that action? Can trafficking take place for a range of end purposes, or is it restricted to enforced prostitution and other forms of sexual exploitation? Can men and boys be trafficked as well as women and girls?