One of the most influential social science papers of the 21st century argued that when countries legalize prostitution between consenting adults, it causes more people to be coerced into sex work.
The study, published in 2013 in the journal World Development, has been used to stop legalization initiatives around the world and to justify harsh new laws that turn customers of voluntary sex work into criminals, often in the name of stopping human trafficking.
Unfortunately, the authors of the study used a flawed economic model and abysmal data to reach their conclusion. When crucial information was missing, they guessed and filled it in. Then, when the analysis didn't yield what seemed to be the authors' desired finding, they threw out the data. There is no evidence that legalizing prostitution increases human trafficking.
