Frances Haugen is set to offer testimony to UK MPs and peers examing the draft of an online safety bill - a piece of legislations placing responsibility on social media companies to shield users from online harm.
Ahead of her hearing before the joint committee, Haugen told The Observer that Facebook CEO Mark Zuckerberg is currently "unaccountable" for his platform's purported failure to protect users from online harm.
"He has no oversight, and he has not demonstrated that he is willing to govern the company at the level that is necessary for public safety", she said.
Haugen is scheduled to speak at 14:00 GMT. Aside from her, another former Facebook employee, Sophie Zhang, testified in the House of Commons earlier in October about how the platform failed to fight election interference and misinformation.
The online safety legislation that would oblige social media companies to shield their users from harmful content became a hot topic in the wake of the slaying of Sir David Amess, a Conservative MP who was stabbed to death on 15 October in Essex. The suspected killer, Ali Harbi Ali, was charged with murder and accused of plotting terrorist attacks.
Amid the aftermath of the Conservative MP's tragic murder, UK Labour leader Keir Starmer, has pointed the finger at social media platforms, saying they "are failing to crack down on extremism" and calling for "tough sanctions".
Prime Minister Boris Johnson in response promised to launch debates on the corresponding measures before Christmas, but later faced criticism from Labour over what the party has called a U-turn on the online safety bill.
"It seems that our relief that Boris Johnson had finally understood the urgency of the Online Safety Bill yesterday (Wednesday) was premature", said Labour Shadow Culture Secretary Jo Stevens, per the BBC. "Not only have the Conservatives U-turned on their commitment to bring the second reading of the Bill to parliament before Christmas, but this also raises questions over whether the prime minister's promise to bring in criminal sanctions will also be quietly shelved".
No date has yet been set for debate on the bill, but Commons leader Jacob Rees-Mogg asserted that the bill was "available for all to look at and consider" and noted that the joint committee would "come up with its wise views" in December.
Facebook in the Crosshairs
Haugen, who is to testify amid the heated discussions around the UK online safety bill, is a vocal critic of Mark Zuckerberg and Facebook, as she has shared a plethora of internal documents that detail the company's failure to protect users from online harm.
The revelations have since prompted a wave of media stories related to Facebook's credibility and struggles with tackling misinformation and harmful content. While many stories have already been published, many more are said to be in the works, according to Axios, which reported that Facebook had warned its employees to brace for more bad press and tough headlines.
Reports emerged that in light of intensified pressure over the allegations, Facebook is set to launch a major rebrand, possibly changing its name in order to become the so-called "metaverse company".