Facebook CEO Mark Zuckerberg admitted today to altering the site’s algorithm to shut down certain speech on the platform.

Facebook CEO Mark Zuckerberg appeared before the Energy and Commerce Committee of the House of Representatives in Washington today where he admitted that Facebook does alter its algorithm to shut down certain types of speech. Marsha Blackburn (R-TN), questioned Zuckerberg saying; “we’ve done one hearing on the algorithms, I chair a communications and technology subcommittee here, we’re getting ready to do a second one on algorithms. We’re going to do one next week on prioritization so I’d like to ask you, do you subjectively manipulate your algorithms to prioritize or censor speech?”

Mark Zuckerberg replied; “Congresswoman, we don’t think what we are doing is censoring speech, I think there are types of content like terrorism which I think we all agree we don’t want to have on our service, so we build a system that can identify those and can remove that content and we’re very proud of that work.” Blackburn took Zuckerberg to task saying; “let me tell you something right now, Diamond and Silk is not terrorism.”

This was a reference to YouTube commentators Diamond and Silk who recently found their Facebook page limited on the platform. Zuckerberg admitted this was a mistake earlier in the hearing when representative Joe Barton asked; “‘Please ask Mr. Zuckerberg why is Facebook censoring conservative bloggers such as Diamond and Silk. Facebook called them unsafe to the community, that is ludicrous, they hold conservative views, that isn’t unsafe.’ What’s your response to that?”

Zuckerberg replied; “Congressman, in that specific case,” replied Zuckerberg; “our team made an enforcement error. And we have already gotten in touch with them to reverse it.” Diamond and Silk, however, claim they have yet to hear any further from Facebook.