By Jeff Horwitz

Facebook Inc. was justified in banning then-President Donald Trump, the company's independent oversight board ruled Wednesday, but didn't appropriately explain if or why the former president should be permanently locked out of the social-media platform.

The board gave Facebook six months to determine whether Mr. Trump should be permanently banned and, if so, to explain that decision more fully.

The decision, which is binding, largely ratifies a choice personally approved by Facebook Chief Executive Mark Zuckerberg in the wake of the Jan. 6 U.S. Capitol riot and could have far-reaching implications for how technology companies police political speech.

"The Board found that, in maintaining an unfounded narrative of electoral fraud and persistent calls to action, Mr. Trump created an environment where a serious risk of violence was possible," the board's opinion stated. "At the time of Mr. Trump's posts, there was a clear, immediate risk of harm and his words of support for those involved in the riots legitimized their violent actions."

The board's decision endorses Facebook's assessment of the risk in allowing Mr. Trump to remain on the platform, while also criticizing the company's broader approach to how it enforces its rules. The board said Facebook failed to offer a clear explanation for Mr. Trump's suspension or determine its duration.

"It is not permissible for Facebook to keep a user off the platform for an undefined period, with no criteria for when or whether the account will be restored," the board said in its decision. "In applying a vague, standardless penalty and then referring this case to the Board to resolve, Facebook seeks to avoid its responsibilities."

The board sidestepped taking a position on whether political favoritism played a role in Facebook's decision on how to handle Mr. Trump. In a conference call after the decision was announced, board Co-Chairman Michael McConnell said the possibility is a legitimate concern.

"When you do not have clarity, consistency and transparency, there's no way to know," said Mr. McConnell, a Stanford University law professor. "This is not the only case in which Facebook has engaged in ad hockery."

A recent Pew Research Center survey found that Americans are split on whether Mr. Trump should be barred from social media, largely along partisan political lines. Roughly 49% of U.S. adults said the former president's accounts should be permanently banned from social-media platforms, while 50% said his accounts shouldn't be banned, according to a Pew survey done in April.

About 88% of Republicans and Republican-leaning independents reported Mr. Trump's accounts shouldn't be banned, while 81% of Democrats and Democratic leaners said his accounts should be banned permanently, according to the survey.

Facebook must reconsider the appropriate punishment for Mr. Trump and explain its decision within six months. In addition to the direct ruling, the board also issued seven recommendations for Facebook for handling high-profile content during crises in the future. Chief among them: explaining what its processes for such decisions are.

"They cannot invent new, unwritten rules when it suits them," said Co-Chairman Helle Thorning-Schmidt, a former Danish prime minister.

In a statement, Nick Clegg, Facebook's vice president of global affairs, said that Facebook would do as the board requested. "We thank the board for the care and attention it gave this case," he said.

The ruling prevents Mr. Trump from regaining the social-media megaphone that he wielded for years and that he has lacked since the industry's major players banned him from posting on their platforms earlier this year, alleging he helped incite the violence at the Capitol. The move also hampers one of his most effective fundraising tools.

While Mr. Trump isn't known to be an avid Facebook user personally, as he was with Twitter, his staff regularly cross-posted his tweets there and used it to reach his more than 35 million followers on the platform.

The Facebook decision was made by five members of the current 20-person Oversight Board, then ratified by a majority of the full board. The identities of the five individuals involved in the decision won't be revealed.

Funded by Facebook through an endowment established in 2019, the Oversight Board is designed to help the company tackle its most contentious content-moderation issues and make policy recommendations. The board operates like a Supreme Court for content; the company can refer cases or individual users can ask the board to review Facebook enforcement decisions.

Facebook joined Alphabet Inc.'s YouTube, Twitter Inc. and other social-media platforms in removing then-president Trump after accusing him of inciting the Jan. 6 insurrection at the Capitol. The riot, which left five people dead, followed a speech by Mr. Trump alleging that November's election had been stolen from him and calling on his supporters to take their grievances to Congress.

Mr. Trump has denied wrongdoing, and his lawyers in the unsuccessful impeachment hearing against him called it "patently absurd" to suggest that he incited violence. Mr. Trump was impeached by the House and was acquitted in the Senate.

The former president has said repeatedly that he believes Silicon Valley's biggest tech firms are biased against him and conservatives generally.

Facebook took down the president's account after determining that two of his posts from that day violated its prohibition of praise for dangerous individuals and organizations. In those posts, Mr. Trump called for peace but said the rioters' rage was justified.

The major social-media platforms all took action against the president's posts that afternoon, then formalized more lasting suspensions in the following days. Facebook announced its ban in a post by Mr. Zuckerberg.

"We believe the risks of allowing the President to continue to use our service during this period are simply too great," Mr. Zuckerberg wrote in a January 7 post, arguing that Mr. Trump was seeking to use the platform to disrupt the peaceful transition of power.

Twitter has since declared its ban of Mr. Trump to be permanent, while YouTube CEO Susan Wojcicki has said the platform will allow his return when it is "safe" to do so.

These decisions have drawn criticism from many Republican lawmakers, who say technology companies are censoring right-leaning viewpoints, and some civil-liberties groups have likewise expressed concern about the industry's control over political speech. Some world leaders unaligned with Mr. Trump also questioned his removal, with Germany's Angela Merkel calling the silencing of a head of state problematic.

Many Democratic lawmakers and civil-rights groups have said the companies were too slow to act against Mr. Trump's provocative social-media activity, which they say set the stage for the violence in the wake of the election.

Without a major social-media platform since the takedowns, Mr. Trump has been communicating with his followers via written press statements. He also maintains a direct line to supporters through his campaign's email database, through which he is fundraising for his political-action committee.

The decision could have major business implications for Facebook. A number of major advertisers temporarily boycotted Facebook last year in protest over what they said was the company's ineffective policing of hate speech. Facebook in recent weeks has reached out to advertising agencies in calls and emails to describe the board's process and emphasize that its corporate management has no sway over the decision, advertising executives said.

Facebook is the only company to have submitted its decision to outside review and comment. Three weeks after suspending Mr. Trump from the platform, Nick Clegg, Facebook's vice president of global affairs, called the ban "necessary and right" but said it was important for the board to consider the case and offer guidance on how to handle alleged misbehavior by heads of state.

The board received voluminous feedback in advance of the decision, getting more than 9,000 public comments, as well as a brief from Mr. Trump.

Partly in response to Mr. Trump's controversial rhetoric about immigrants and Muslims during the 2016 presidential campaign, Facebook carved out a "newsworthiness exemption" from its policies against hate speech. In 2019, the company formalized protections for political figures with rules exempting them from fact-checking, saying it was inappropriate for the company to referee political debates.

Facebook always maintained that speech that it deems to be incitement to violence wouldn't be tolerated from any user.

Formed last year, the Oversight Board includes lawyers, human-rights advocates and former politicians drawn from around the world.

The board's first round of decisions struck a free-speech-friendly tone, with members rebuking Facebook for taking down posts questioning the sanity of Muslim men and supporting the availability of Covid-19 treatments generally rejected by public health authorities.

Although the board initially promised to weigh in on Mr. Trump's ban within 90 days, it postponed the decision to consider public comments.

--Alexandra Bruell and Suzanne Vranica contributed to this article.

Write to Jeff Horwitz at Jeff.Horwitz@wsj.com

(END) Dow Jones Newswires

05-05-21 1054ET