Former US president Donald Trump has filed suit against three of the country’s biggest tech companies, claiming he and other conservatives have been wrongfully censored.

Mr Trump announced the class action against Facebook, Twitter and Google’s YouTube, along with the companies’ CEOs, in New Jersey on Wednesday (local time).

The lawsuits come six months after Mr Trump was permanently or temporarily suspended from all three platforms.

He was joined by other plaintiffs in the suits, which were filed in federal court in Miami.

“We’re demanding an end to the shadow-banning, a stop to the silencing and a stop to the blacklisting, banishing and cancelling that you know so well,” he said.

Under Section 230 of the 1996 Communications Decency Act, social media platforms are allowed to moderate their services by removing posts that, for instance, are obscene or violate the services’ own standards, so long as they are acting in “good faith”.

The law also generally exempts internet companies from liability for the material that users post.

But Mr Trump and some other politicians have long argued that Twitter, Facebook and other social media platforms have abused that protection and should lose their immunity – or at least have to earn it by satisfying requirements set by the government.

Mr Trump was suspended from Twitter, Facebook and YouTube after his followers stormed the US Capitol building on January 6.

The companies cited concerns that he would incite further violence.

The suits argue that banning or suspending Trump and the other plaintiffs is a violation of the First Amendment, despite the fact that the companies are private.

The suit against Facebook and CEO Mark Zuckerberg says Facebook acted unconstitutionally when it removed Mr Trump from the platform.

Suits against Twitter and YouTube make similar claims.

All three ask the court to award unspecified damages, declare Section 230 unconstitutional and restore Mr Trump’s accounts, along with those of the other plaintiffs – a handful of others who have all had posts or accounts removed.

But Mr Trump’s lawsuits are likely doomed to fail, said Eric Goldman, a law professor at Santa Clara University in California who has studied more than 60 similar, failed lawsuits over the past few decades that sought to take on internet companies for terminating or suspending users’ accounts.

“They’ve argued everything under the sun, including First Amendment, and they get nowhere,” Mr Goldman said.

“Maybe he’s got a trick up his sleeve that will give him a leg up on the dozens of lawsuits before him. I doubt it.”

Mr Goldman said it’s likely Mr Trump is instead pursuing the suits to garner attention.

As president, Mr Trump last year signed an executive order challenging Section 230.

“It was always about sending a message to their base that they’re fighting on their behalf against the evil Silicon Valley tech giants,” Mr Goldman said.

-with AAP