President Donald Trump said he signed an executive order to “defend free speech” from social-media companies by limiting their legal protections from liability — an action he took two days after Twitter applied fact-checking labels to two of his inaccurate tweets about mail-in ballots.

The White House announced Trump’s order seeking to limit legal protections of social-media companies on Twitter, Facebook and Instagram. The text of the order is available at this link.

According to Trump, the executive order calls for new regulations under Section 230 of the 1996 Communications Decency Act that would remove the legal liability shield for social networks that “engage in censoring or any political conduct.” The law, as it currently stands, lets companies like Facebook, YouTube and Twitter moderate content on their services as they see fit, while protecting them from lawsuits over content shared on them.

“We’re here today to defend free speech from one of the gravest dangers it has faced in American history, frankly,” Trump said in announcing the executive order, according to video released by the White House.

Despite Trump’s posturing, legal experts say any attempts to alter Section 230 of the law would be met with a court challenge and that his executive order is likely unconstitutional, representing a violation of the First Amendment.

“It’s political theater. It mischaracterizes the law and exceeds executive authority,” Jonathan Peters, a media law professor at the University of Georgia’s Grady College of Journalism and Mass Communication and an affiliate assistant professor with UGA’s School of Law, said in a Twitter post.

Trump’s order is “plainly illegal,” Sen. Ron Wyden (D-Ore.), who coauthored Section 230 of the CDA, said in a statement.

“After driving our country into an economic and health care disaster, Trump is desperately trying to steal for himself the power of the courts and Congress to rewrite decades of settled law around Section 230. All for the ability to spread unfiltered lies,” Wyden’s statement said in part. “Donald Trump’s misinformation campaigns have left death and destruction in their wake. He’s clearly targeting Section 230 because it protects private businesses’ right not to have to play host to his lies.”

Trump, in signing the order, complained that companies “like Twitter enjoy an unprecedented liability shield based on the theory that they are a neutral platform, which they are not.” His executive order also directs the administration to withhold “taxpayer dollars” from social media companies that “repress free speech.”

It is not clear whether the U.S. president understands that private companies like Twitter and Facebook are not subject to regulation under the Constitution’s First Amendment free-speech protections.

On Wednesday, the D.C. Court of Appeals ruled in favor of Google, Facebook, Twitter and Apple in a lawsuit filed by right-wing activists alleging the tech giants suppressed “politically conservative voices.” The court tossed the suit, ruling that the First Amendment applies only to government entities and not private companies.

“Much as he might wish otherwise, Donald Trump is not the president of Twitter,” ACLU senior legislative counsel Kate Ruane said in a statement. After the order was released, she commented, “The First Amendment forbids such blatant, thin-skinned efforts to stifle expression. President Trump has it backwards: The First Amendment protects us from the government, not the government from us.”

Trump’s executive order directs the FCC to “expeditiously propose regulations” to, among other things, “clarify and determine the circumstances under which a provider of an interactive computer service that restricts access to content in a manner not specifically protected… may also not be able to claim protection” under Section 230.

Per the text of Section 230, the law grants immunity to internet services that take action “in good faith to restrict access to or availability of material that the provider or user considers to be obscene, lewd, lascivious, filthy, excessively violent, harassing, or otherwise objectionable.”

“Even if the FCC issued the rules Trump wants, enforcing them would be unconstitutional,” said Ashkhen Kazaryan, director of civil liberties at TechFreedom, a nonpartisan think tank. She called Trump’s order a “hodgepodge of outdated and inapplicable precedents combined with flagrant misinterpretations of both the First Amendment and Section 230,” noting that the Supreme Court has rejected the argument that Twitter and Facebook are “the functional equivalent” of a traditional public forum.

In announcing the executive order, the president said about social-media companies, “They’ve had unchecked power to censor, restrict, edit, shape, hide, alter virtually any form of communication between private citizens or large public audiences.” Trump also said, “A small handful of powerful social-media monopolies controls a vast portion of all public and private communications in the United States. And we know what they are… We’re gonna give you a complete listing.” The text of the executive order names Twitter, Facebook, Instagram and Google’s YouTube.

Twitter’s Public Policy team said Trump’s executive order “is a reactionary and politicized approach to a landmark law. #Section230 protects American innovation and freedom of expression, and it’s underpinned by democratic values. Attempts to unilaterally erode it threaten the future of online speech and internet freedoms.”

After Twitter labeled Trump’s tweets as misleading on May 26 — and directed users to a fact-checking page debunking his lies about mail-in ballots — the president’s supporters and a top White House aide launched targeted attacks on an individual Twitter employee who has posted anti-conservative tweets.

On Thursday, Trump, before signing the executive order, lashed out again at Twitter — on the company’s platform, where he has 80.4 million followers — and also named the Twitter employee his followers have targeted.

“So ridiculous to see Twitter trying to make the case that Mail-In Ballots are not subject to FRAUD,” the president tweeted. (Twitter’s fact-check of Trump’s misleading tweets did not make that assertion; its page on the subject points out that “Experts say mail-in ballots are very rarely linked to voter fraud.”) Trump continued, “How stupid, there are examples, & cases, all over the place. Our election process will become badly tainted & a laughingstock all over the World. Tell that to your hater. Tell that to your hater @yoyoel,” which is the account name of Yoel Roth, Twitter’s head of site integrity.

Twitter CEO Jack Dorsey, in a series of posts Wednesday about the controversy, said, “there is someone ultimately accountable for our actions as a company, and that’s me. Please leave our employees out of this.”

Dorsey also said that Twitter plans to keep fact-checking information posted on the service. “We’ll continue to point out incorrect or disputed information about elections globally,” Dorsey wrote.

Meanwhile, Facebook CEO Mark Zuckerberg, in an interview with Fox News Channel’s “The Daily Briefing” that aired Thursday, sought to distance his company’s fact-checking approach from Twitter’s.

“We have a different policy I think than Twitter on this,” Zuckerberg said. “You know, I just believe strongly that Facebook shouldn’t be the arbiter of truth of everything that people say online… We’ve been pretty clear on our policy that we think that it wouldn’t be right for us to do fact-checks for politicians.”

Dorsey, evidently subtweeting Zuckerberg, said that Twitter’s fact-checking “does not make us an ‘arbiter of truth.’ Our intention is to connect the dots of conflicting statements and show the information in dispute so people can judge for themselves.”

The irony is that if Trump actually prevails in stripping legal protections from internet companies, he might swiftly get kicked off social media.

“If platforms were not immune under the law, then they would not risk the legal liability that could come with hosting Donald Trump’s lies, defamation and threats,” the ACLU’s Ruane noted.

In recent weeks, Trump has posted multiple tweets promoting a long-debunked conspiracy theory that MSNBC host Joe Scarborough may have killed a former congressional aide in 2001. The company apologized for the “pain” Trump’s comments have caused to the family of the dead woman, Lori Klausutis. That came after Timothy Klausutis, her widowed husband, appealed to Dorsey to stop Trump and others from “spreading this vicious lie.” But Twitter so far has not taken any action against Trump’s account or tweets on the matter. Dorsey, at the company’s shareholders meeting Wednesday, said the legal system provides a better avenue for users to settle disputes about statements posted on Twitter.