Angered by Twitter’s moves to fact-check him, President Trump signed an executive order cracking down on social media sites, though it’s unclear if he has the authority to revise the relevant law, which Congress passed in 1996.
The order seeks to strip liability protection in certain cases for companies like Twitter, Google and Facebook, making it easier for people to sue them over their content.
Legal experts say the order is almost certain to face a court challenge. It could also backfire on Mr. Trump: Without the liability shield, social media platforms may be forced to remove posts that could be considered false or defamatory — the boundaries of which Mr. Trump often tests.

Maggie Haberman and Kate Conger