From 1800 prostitution (assumed only to be female) was regulated in Europe, but it was tolerated as it was deemed necessary for male sexuality. The system of regulationism, accused in the 1860s of iniquity by the abolitionist movement, was then called into question by the development of a White Slave Trade involving innocent victims. This “scourge” led states to search for a European or even international solution. Addressed by international organisations (the League of Nations and United Nations) the issue became topical again in the second half of the twentieth century owing to the influx of prostitutes from Eastern Europe. The European Union attempted to respond to the challenge posed by what was now described as human trafficking, but respected the diversity of national policies towards prostitutes and the potential normalisation of prostitutes as sex workers.