The celebrity, identified only as 'PJS', claimed his right to privacy outweighed an English tabloid newspaper's right to publish a story about his open relationship with his partner 'YMA'.
Philip Davies MP, a member of the Commons' justice select committee, said: "This is an absolute farce.
"I have never encountered anything quite so ridiculous as this in my life.
"Judges who keep making these rulings are completely out of touch with what is right. They need to get real with the modern world.
"I don't think celebrities who use the media to secure positive media coverage when it suits them should be able to use the law of the land to prevent coverage they do not like."
He added: "Someone in the northern parts of England who is banned from knowing this information could walk to Scotland and read it in the newspapers there - it's an absolute mockery."
John Hemming, the former Liberal Democrat backbencher who publicly identified footballer Ryan Giggs in the House of Commons in connection with a 2011 injunction, has called on Parliament to look again at the law.
"It's absurd trying to hold back the flow of information in the digital age by using a court order that can only go as far as Hadrian's Wall," he said.
"It undermines public debate in England and Wales.
"Although the matter at the centre of this injunction is a trivial one, the issues it creates are vital ones which go to the heart of free speech.
"At a time when so much is focused on the impact of the Panama papers, there is a need for transparency in all matters of public interest."
A High Court judge initially refused PJS's application for an injunction and said the newspaper was entitled to "correct" the "public image" presented by the celebrity when he had engaged in that sort of "casual sexual relationship".
PJS then went to the Court of Appeal.
There, Lord Justice Jackson and Lady Justice King said in their ruling that PJS met someone called AB in 2007 or 2008 and had "occasional sexual encounters starting in 2009".
In a text message to AB on December 15, 2011, PJS asked whether AB's partner, known only as CD, was "up for a three-way".
"AB said that CD was," Lord Justice Jackson said in the ruling.
"Accordingly, the three met for a three-way sexual encounter which they duly carried out."
The sexual relationship between PJS and AB ended and they remained friends.
But AB later went to The Sun on Sunday with his story, prompting legal action by the celebrity.
The appeal judges observed PJS and YMA were a "committed couple" and PJS's "occasional sexual encounters with others do not detract from that commitment".
The proposed story about his sex life would be "devastating" for PJS and his rights under Article 8 outweighed the newspaper's rights under Article 10 to publish, Lord Justice Jackson said.
Bob Satchwell, executive director at the Society of Editors, said last week: "It is quite ridiculous that people elsewhere can know about the story but people in Britain are not allowed to.
"It makes a mockery of the system."
Last week The Telegraph disclosed the Government is poised to weaken celebrities' ability to obtain court injunctions amid the "threesome" outcry.
Ministers are "actively considering" a change in the law which will stop wealthy individuals - including famous public figures - using Labour's Human Rights Act to stop newspapers publishing material that is in the public interest.
A host of previous cases have seen injunctions used by the rich and famous to prevent newspapers reporting their activities.
Another type of court order, the "super-injunction", forbids publications even referring to such legal actions - and were widely considered to be stifling free speech.
