Facebook violates Europe's privacy law by placing tracking cookies on users who visit sites with a “Like” button -- even if those users don't have Facebook accounts or have opted out of online tracking, according to a new study. The study, authored by researchers from the University of Leuven and Vrije Universiteit Brussels, was commissioned by Belgian regulators after an earlier report found that Facebook's privacy policy violates European law, accordimg to the Guardian. The EU's privacy law requires generally companies to obtain users' consent before placing tracking cookies on their computers.