In international debates on prostitution policy and in debates on prostitution that takes place within individual countries, references are often made to “the Nordic” or “the Swedish” model of prostitution policy. In Sweden, Norway and Iceland, the purchase of sex is a criminal offence, while it remains legal to sell sex. In debates references are made to the effects of such a policy on the extent of human trafficking. While politicians and activists are eager to treat this particular way of regulating prostitution either as a great success or a great failure, researchers need to take into consideration how a country’s anti-trafficking and anti-prostitution efforts impact identification of cases and therefore available figures. In this chapter we investigate the evidence for how the Swedish Sex Purchase Act influences trafficking to Sweden, and we particularly argue that researchers must avoid underestimating the complexity of the relationship between law and the phenomena they regulate.