Live: Facebook CEO Mark Zuckerberg testifies before Congress

Facebook CEO Mark Zuckerberg is testifying before US Congress, where he is answering questions from lawmakers about issues including the company’s handling of user data. The joint hearing of the Senate Commerce and Judiciary Committees comes amid questions over how Russia used the social network to spread divisive political messages during the 2016 US presidential election, and how data analysis firm Cambridge Analytica harvested the personal data of some 87 million Facebook users. The testimony marks the first time that 33-year-old Zuckerberg has faced Congress. In his opening statement, Zuckerberg acknowledged that the company faces “a number of important issues around privacy, safety, and democracy.” “It’s clear now that we didn’t do enough to prevent these tools from being used for harm as well. That goes for fake news, foreign interference in elections, and hate speech, as well as developers and data privacy,” he said.  "We didn't take a broad enough view of our responsibility, and that was a big mistake. It was my mistake, and I'm sorry. I started Facebook, I run it, and I'm responsible for what happens here." Follow our live blog of the testimony, and watch it on the player.