A week ago, an ad placed by the Trump campaign made similarly false corruption accusations about Mr. Biden. At the time, Mr. Biden’s campaign also sent Facebook a letter asking for the ad’s removal. Facebook refused, saying the ad was from a political leader and thus in the public interest.
That decision was criticized by the Biden campaign and Senator Elizabeth Warren, the Democrat from Massachusetts, who has promised to break up Facebook if elected president. Ms. Warren later posted a deliberately false ad on Facebook about Mr. Zuckerberg and Mr. Trump, daring the company to take it down.
The super PAC’s ad this week opened with a silhouette of Mr. Biden in front of an image of the White House. A narrator in a foreboding voice claimed the former vice president had blackmailed and threatened to withhold aid from Ukraine to stop an investigation into a company associated with his son Hunter.
Six versions of the ad were targeted to Facebook users in South Carolina, Iowa and Massachusetts, according to Facebook’s ad library. All versions are no longer active.
For years, Facebook has been assailed for unevenly enforcing its content policies across its family of apps, including Instagram, WhatsApp and Facebook Messenger. The company often reacted to problematic content that surfaced and made seemingly arbitrary decisions to reinstate or remove a given post.
In one of the best-known incidents, in 2016, moderators took down the Pulitzer Prize-winning image of Phan Thi Kim Phuc, the 8-year-old girl who was photographed fleeing napalm bombs during the Vietnam War. Because Ms. Phuc was naked, the image was removed from Facebook for reasons of child pornography. When Facebook was told about the news value of the image, it was allowed to remain.
Facebook does not permit certain types of material, such as pornography and posts that could incite violence, including hate speech and “dehumanizing” language.