Mark Zuckerberg appeared to stumble when confronted with tough questioning by congresswoman Alexandria Ocasio-Cortez, who asked the Facebook CEO if a right-wing news outlet known for its ties to white supremacist groups is an appropriate fact-checking group to help oversee the social media giant's content.
Ms Ocasio-Cortez confronted Mr Zuckerberg during congressional testimony on Wednesday, where the CEO was due to discuss a cryptocurrency favoured by his company. But the Democrat instead chose to grill him about Facebook's decision not to fact check political advertisements, even in cases where messages posted by politicians are clearly wrong. She also asked about Mr Zuckerberg's previous admission that he dines regularly with conservatives and right-wing personalities, which he said is part of his strategy to ensure he hears a diverse set of opinions.
"Can you explain why you have named the Daily Caller, a publication well documented with ties to white supremacists as an official fact checker for Facebook?" Ms Ocasio-Cortez asked.
Mr Zuckerberg replied that Facebook does not itself appoint fact checkers on its platform, and instead relies on the International Fact Checking Network (IFCN), a fact checking organisation established by the journalism integrity group Poynter.
"You would say that white supremacist tied publications meet a rigorous standard for fact checking?" Ms Ocasio-Cortez responded.
At this point, Mr Zuckerberg turns his head away and stares ahead for a moment, appearing to look for some form of guidance.
He then responds: "Congresswoman I would say that we're not the ones assessing that standard, the International Fact Checking Network is the one setting that standard.
The Independent has reached out to IFCN for comment and clarification.