For nearly four years, the social media companies have had time to develop content policies to be ready for the 2020 election, especially after Russian operatives were found to have used the sites to sow discord in the 2016 election. But even with all the preparations, the volume of last-minute changes by Twitter and Facebook suggests that they still do not have a handle on the content flowing on their networks.
That raises questions, election experts said, about how Twitter and Facebook would deal with any interference on Election Day and in the days after. The race between Mr. Trump and his Democratic challenger, Joseph R. Biden Jr., has been unusually bitter, and the social media sites are set to play a significant role on Nov. 3 as distributors of information. Some people are already using the sites to call for election violence.
The chaotic environment could challenge the companies’ policies, said Graham Brookie, director of the Digital Forensic Research Lab, a center for the study of social media, disinformation and national security. “Everybody has a plan until they get punched in the face,” he said.
Other misinformation experts said Twitter and Facebook have had little choice but to make changes on the fly because of the often norm-breaking behavior of Mr. Trump, who uses social media as a megaphone.
Alex Stamos, director of the Stanford Internet Observatory and a former Facebook executive, noted that after Mr. Trump recently made comments to his supporters to “go into the polls and watch very carefully,” some companies — like Facebook — created new policies that forbid a political candidate from using their platforms to call for that action. The companies also prohibited candidates from claiming an election victory early, he said.
“These potential abuses were always covered by very broad policies, but I think it’s smart to commit themselves to specific actions,” Mr. Stamos said.
From the start, the New York Post article that Twitter blocked was problematic. The article featured purported emails from Hunter Biden, a son of Joe Biden, and discussed business in the Ukraine. But the provenance of the emails was unclear, and the timing of their discovery so close to the election appeared suspicious.