Former President Donald Trump is suing Facebook, Twitter and Google's YouTube over their suspensions of his accounts after a mob of his supporters attacked the U.S. Capitol in January.

Trump filed class action complaints in federal court in Florida, alleging the tech giants are censoring him and other conservatives — a long-running complaint on the right for which there is little evidence and that the companies deny.

The suits call for the court "to order an immediate halt to social media companies' illegal, shameful censorship of the American people," Trump said at a news conference at his golf club in Bedminster, N.J. "We're demanding an end to the shadow banning, a stop to the silencing and a stop to the blacklisting, banishing and canceling that you know so well."

The long-shot legal actions are the latest escalation in Trump's long-running feud with the social media platforms that he used prolifically before and during his presidency.

After the Jan. 6 insurrection at the U.S. Capitol, the companies kicked Trump off their platforms, citing the risk of further violence. Twitter banned Trump permanently, Facebook has suspended him for two years and YouTube has said it will let him return only "when we determine that the risk of violence has decreased."

In Tuesday's lawsuits, the former president accuses the companies of violating his First Amendment rights and of behaving like "state actors" rather than private companies in putting restrictions on what people can post.

He has asked the court to order the companies to reinstate him and other members of the proposed class of plaintiffs.

He also wants the court to declare a federal law, Section 230 of the Communications Decency Act, unconstitutional. That 1996 law says online sites largely are not legally responsible for what their users post. While in office, in retaliation for Twitter's fact-checking of his tweets, Trump signed an executive order attempting to strip social media companies of Section 230 protection. (President Biden has revoked the order.)

In addition to the companies, the lawsuits name Facebook CEO Mark Zuckerberg, Twitter CEO Jack Dorsey and Google CEO Sundar Pichai as defendants, although not YouTube CEO Susan Wojcicki.

Spokespeople for Facebook and Twitter declined to comment. YouTube and Google did not respond to a request for comment.

Legal experts say Trump's lawsuits are likely doomed from the start because of the strong protections that both Section 230 and the First Amendment give the companies to decide what speech they allow.

"Trump has the First Amendment argument exactly wrong," said Paul Barrett, an adjunct law professor and deputy director at New York University's Center for Business and Human Rights. He described the lawsuits as "DOA," or dead on arrival, because the First Amendment applies to government restrictions on speech, not the actions of private companies.

Even conservative experts voiced skepticism about Trump's legal case.

"These social media platforms are private property, not the government town square, and are well within their First Amendment rights to refuse to carry speech of third parties. This principle holds even with the former president of the United States and is the constitutional right of every citizen," said Jessica Melugin at the Competitive Enterprise Institute. "This lawsuit is a publicity stunt intended for political gain, not a serious legal argument."

Previous attempts to sue the platforms over their content-moderation decisions have been quickly tossed by courts. Last week, a federal judge blocked a new Florida law from taking effect. It would have fined large social media companies if they banned politicians. The court said the law likely violated the First Amendment.

Section 230 has come under broader scrutiny from both Republicans and Democrats in recent years, with lawmakers on both sides of the aisle saying its liability protections should be pared back. However, they are divided on what reform would look like, with Republicans focusing their criticisms on alleged censorship and Democrats seeking to hold the companies more responsible for misinformation and other harmful content.

Editor's note: Facebook and Google are among NPR's financial supporters.