A refugee advocate has won an appeal against a defamation ruling which ordered him to pay Defence Minister Peter Dutton $35,000 over a now-deleted tweet.
Mr Dutton sued Shane Bazzi in the Federal Court over the tweet, published in February last year, which accused him of being "a rape apologist".
It also linked to news story containing comments Mr Dutton made about women on Nauru when he was Home Affairs Minister.
Mr Bazzi argued he was exercising fair comment and honest opinion.
He launched an appeal after Justice Richard White last year found the tweet conveyed the defamatory imputation that Mr Dutton "excuses rape".
The Full Court of the Federal Court, comprising Justices Steven Rares, Darryl Rangiah and Michael Wigney, overturned the original decision.
In the original ruling, Justice White referred to the "contemporaneous controversy" which developed prior to the tweet about an allegation of rape made by Brittany Higgins.
He found that "in a general way" Mr Dutton's statements about aspects of the allegations, in a doorstop interview, formed "part of the context" in which Mr Bazzi published the tweet.
In a joint judgment, Justices Rares and Rangiah found Justice White erred in his reasoning process because he "did not explain how the reader would understand the whole (or any part) of the tweet to convey the imputation".
They noted Justice White found the meaning of the word "apologist" was not that of an excuser but a defender.
The judges said Mr Bazzi's six words, by themselves, could mean Mr Dutton defends or is a defender of rape, but it was unlikely such a meaning would reasonably occur from the content of the tweet including the material in the news story.
The article, published by The Guardian in June 2019, contained comments Mr Dutton made alleging women had been "trying it on" claiming they were raped and needed an abortion as a ploy to get to Australia from Nauru.
The court found the two components of the tweet would convey they were connected, and the reader would think the article was included was to illustrate the point of Mr Bazzi's "polemic denunciation of Mr Dutton".
The broad impression was that the tweet was "derogatory" of Mr Dutton, the court found.
Its proposition was that Mr Dutton's "scepticism" about the Nauru women's claims of rape, expressed in the article, supported Mr Bazzi's description of him.
"When that material is read with Mr Bazzi's six words, the reader would conclude that the tweet was suggesting that Mr Dutton was sceptical about claims of rape and in that way was an apologist," the judgment said.
"But that is very different from imputing that he excuses rape itself."
The judges said it was not sufficient that the tweet was "offensive and derogatory" and Mr Dutton had failed in his onus to establish that the reader reasonably would have understood the imputation he asserted.
Justice Wigney also said the primary judge erred in finding the tweet conveyed the imputation and "substantially agreed" with Justices Rares and Rangiah in their reasoning.
Outside court, Mr Bazzi thanked his legal team and said the case had taken a "tremendous toll" on him.
"This case was not just about me," he said.
"It was about anyone who wants to make political comment or criticism on social media.
"I feel very grateful that the court has set such a clear and compelling precedent."
Lawyer Stewart O'Connell said the ruling was a "David and Goliath" moment and that Mr Bazzi had been "extraordinary" in standing his ground.
He said the case should not result in people being hesitant to criticise politicians on social media.
"The judgement is saying you can criticise politicians, you can make derogatory comment in a political context," he said.
"There are boundaries and politicians, like anyone, should be able to sue if their personal reputation is defamed.
"But where it is a political comment, then there should be a large degree of freedom to make that.
"So I don't think people should fear making adverse opinions or comments about politicians."
NSW Greens MP David Shoebridge said about $157,000 had been raised in a crowdfunding campaign to defend the case, and much of the money could go to charities such as rape and domestic violence centres or refugee crisis centres.
"That will all be courtesy of Peter Dutton paying the costs of Shane Bazzi," Mr Shoebridge said.
"This is a win for democracy. It's a win for people who want to be able to critique powerful politicians without being squashed by a legal suit."
