MADRID—Spanish Prime Minister Pedro Sanchez is vowing to outlaw prostitution, arguing that it “enslaves” women. While Spain decriminalized the practice in 1995, Sanchez’s Socialist Party now wants to go the way of Sweden, where it is illegal to buy sex but not to sell it. The Spanish government’s about-face illustrates how in the past few decades, Europe has become a laboratory for policies to address not only prostitution itself, but also the ways in which it goes hand-in-hand with human trafficking. Whereas countries like Norway and France have followed Sweden’s lead in trying to ban the practice on the demand […]