The Article 29 Working Party, a group of European privacy experts, warned WhatsApp that it is still not complying with data protection law. Following Facebook's acquisition of WhatsApp, WhatsApp transferred users' personal data to Facebook, violating past privacy promises. In a letter to WhatsApp, Article 29 said "the information presented to users was seriously deficient as a means to inform their consent," and a WhatsApp must promptly establish "clear, comprehensive resolution." Backed by over a dozen US consumer groups, in 2016 EPIC filed a complaint with the FTC urging the agency to block Facebook's acquisition of WhatsApp if privacy safeguards were not put in place. The FTC wrote to both companies, explaining that their failure to honor privacy obligations could violate U.S. law.