https://phys.org/news/2018-07-facebook-discriminatory-ad-washington-attorney.html > On Tuesday, under pressure from the investigation, Facebook signed a legally binding document in court in Seattle requiring it to shut down the advertising tool for businesses looking to exclude demographics protected under state law. > The practice, first unveiled in a series of ProPublica articles that sparked the attorney general's investigation, is one of several issues facing Facebook's lucrative advertising network, which allows anyone from presidential candidates to the local flower-shop owner to micro-target its billions of users.