Revelations brought to light from whistleblower Frances Haugen, a former data scientist at Facebook, has led to what may be the most threatening scandal in the company's history.
The pressure was turned up on Tuesday, when Haugen testified before a Senate subcommittee. She provided a clear and detailed glimpse inside the notoriously secretive tech giant. She said Facebook harms children, sows division and undermines democracy in pursuit of breakneck growth and "astronomical profits."
Past controversies over Facebook's role in Russian attempts to influence the 2016 election and the social network's lax handling of user data in the Cambridge Analytica case were crises that rocked the company and spurred internal reform.
But the fury that Haugen's revelations have set off is different. Here are four reasons why.
Haugen was an insider, making her a powerful critic
Haugen worked at Facebook for nearly two years after stints at Google, Yelp and Pinterest.
At Facebook, she studied how the social network's algorithm amplified misinformation and was exploited by foreign adversaries.
Haugen told Congress that Facebook consistently chose to maximize its growth rather than implement safeguards on its platforms, just as it hid from the public and government officials internal research that illuminated the harms of Facebook products.
"The result has been more division, more harm, more lies, more threats and more combat. In some cases, this dangerous online talk has led to actual
violence that harms and even kills people," Haugen testified.
Before Haugen left the social network, she copied thousands of pages of confidential documents and shared them with lawmakers, regulators and The Wall Street Journal, which published a series of reports called the Facebook Files.
"During my time at Facebook, I came to realize a devastating truth: Almost no one outside of Facebook knows what happens inside Facebook," Haugen told Congress. "The company intentionally hides vital information from the public, from the U.S. government, and from governments around the world."
Haugen is not the first ex-Facebook employee who has raised concerns about the world's largest social network. But two things distinguish her: She is a compelling witness, speaking with conviction, specificity and depth. And she came armed with receipts to buttress her account — the thousands of pages of company documents that lay bare exactly what Facebook knew about its products.
Research shows Facebook coveted young users, despite health concerns
Of particular concern to lawmakers on Tuesday was the impact on children by Instagram, which is owned by Facebook.
Haugen has leaked one Facebook study that found that 13.5% of U.K. teen girls in one survey say their suicidal thoughts became more frequent after starting on Instagram.
Another leaked study found 17% of teen girls say their eating disorders got worse after using Instagram.
About 32% of teen girls said that when they felt bad about their bodies, Instagram made them feel worse, Facebook's researchers found, which was first reported by the Journal.
Sen. Marsha Blackburn, R-Tenn., accused Facebook of intentionally targeting children under age 13 with an "addictive" product — despite the app requiring users be 13 years or older.
"It is clear that Facebook prioritizes profit over the well-being of children and all users," she said.
Subcommittee Chair Richard Blumenthal, D-Conn., echoed this concern.
"Facebook exploited teens using powerful algorithms that amplified their insecurities," Blumenthal said. "I hope we will discuss as to whether there is such a thing as a safe algorithm."
Haugen told Congress that when outside researchers and lawmakers asked how Facebook affected the health and safety of children, the company was never forthcoming.
"Facebook chooses to mislead and misdirect. Facebook has not earned our blind faith," Haugen told Congress.
According to Haugen's legal team, Facebook executives, including CEO Mark Zuckerberg, misstated and omitted key details about what was known about Facebook and Instagram's ability to cause harm.
Attorneys for Haugen allege that Facebook violated U.S. securities laws by lying to investors.
The documents were also shared with state prosecutors, including the California attorney general, Haugen's lawyer, John Tye, told NPR.
Federal regulators and state prosecutors have not indicated how authorities plan to respond.
Facebook is turning up the heat on Haugen, suggesting for the first time that she broke the law. Company executive Monika Bickert told CNN on Tuesday that the documents Haugen obtained were "stolen."
Federal whistleblower protections provide legal cover to Haugen in providing private Facebook documents to the SEC and Congress, but experts say her leaks to the press could trigger legal action from Facebook.