A US politician has accused Twitter and three of its users of running an "orchestrated defamation campaign" against him.
Republican congressman Devin Nunes of California has said that tweets from the parody accounts @DevinNunesMom and @DevinCow violate the platform's Terms of Service.
Their tweets accuse him of federal crimes and describe him engaging in sexual activities with US president Donald Trump.
He is suing for $250m (£188m).
"Twitter knew the defamation was (and is) happening. Twitter let it happen because Twitter had (and has) a political agenda", he wrote in a 40-page complaint.
He says he has suffered "substantial insult, humiliation, embarrassment, pain, mental suffering and damage to his reputation" from the Twitter insults.
Mr Nunes served as the chair of the US House Intelligence Committee until 2019. He became a controversial figure for his vocal support of President Trump during the investigation into Russian interference in the US presidential election.
He was also the centre of an investigation of the House Ethics Committee in 2017, after he released a memo claiming that the intelligence community monitored communications between members of Trump's transition team (of which he was a part). He was cleared of any wrongdoing.
He is now claiming that Twitter "selectively amplified" tweets that attempted to distract him from that investigation.
Mr Nunes says that the the accounts @LizMair, @DevinNunesMom and @DevinCow led a coordinated smear campaign against him - although fringe accounts such as @fireDevinNunes and @DevinGrapes also dished up insults.
Tweets from the accounts have accused him of crimes such as obstructing justice and perjury. Some posts have referred to him as "Dirty Devin" and described him engaging in sexual activities with President Trump. Mr Nunes has said that these allegations are false.
It isn't uncommon for public figures - particularly politicians - to have to contend with parody accounts. PM Theresa May has inspired @Theresa_May_Not, @TheresaGoogling, @DowningStVogue and @emayji (a play on "emoji"). President Trump has also prompted sarcastic spin-offs mocking his policies, such as @donaltrumparody and @realDonaldTrFan.
According to Mr Nunes, Twitter suspended the @DevinNunesMom account in 2019, before he filed the complaint. The @DevinCow account is still active, and has reached more than 48,000 followers since Mr Nunes filed his complaint on Monday.
Although Mr Nunes claims that the @DevinNunesMom account "hijacked Nunes' name" and "falsely impersonated Nunes' mother", Twitter's policies do not ban parody and fan accounts - so long as the biography and account name clearly indicate that the user is not affiliated to the subject.
In his complaint, Mr Nunes suggests that they are part of a larger conspiracy, and that an investigation will help determine whether members of the Democratic Party were involved.
What is shadow-banning?
Mr Nunes says that Twitter "shadow-banned" his account, using algorithms to make certain posts invisible to other users.
Twitter's CEO Jack Dorsey has come under fire from politicians in recent years, including US president Donald Trump, for censoring conservative voices.
In a hearing before US senators in 2018, Mr Dorsey admitted that the company's algorithms inadvertently reduced the visibility of 600,000 accounts - but that the company "does not use political ideology to make decisions". Although some accounts weren't appearing in search results on the platform, this was due to follower behaviour on the platform, not political affiliation.
Mr Nunes does not describe how Twitter shadow-banned his account in the complaint he filed. Most of the complaint instead focuses on the three accounts that he claims posted defamatory content, and Twitter's failure to enforce its Twitter Rules and Terms of Service.
"Twitter, by its actions, intended to generate and proliferate the false and defamatory statements," he said.