Firebrand politician Mark Latham has been ordered to pay $140,000 after a court ruled his explicit tweet exposed an independent MP to a “maelstrom” of abuse.

The tweet stemmed from a heated online argument with independent NSW MP Alex Greenwich and conveyed the meaning that he “engages in disgusting sexual activities”, the Federal Court was told.

Greenwich, who is gay and a vocal advocate for LGBTQI issues, sued the former NSW One Nation leader over the tweet sent in March 2023, days after the state election.

On Wednesday, the court ordered Latham pay Greenwich $100,000 in damages for non-economic loss and a further $40,000 in aggravated damages.

The former One Nation NSW leader’s tweet described a sex act in explicit terms and was in response to a post quoting Greenwich describing him as a “disgusting human being”.

Justice David O’Callaghan found Greenwich was exposed to a torrent of offensive and hateful messages as a result of Latham’s tweet, despite noting that much of the material might be “the product of people with deranged minds”.

“There is no doubt that as a result of the publication of the primary tweet, for which Mr Latham offered no genuine apology, Mr Greenwich suffered a loss of standing,” he said in his judgment.

“He was exposed to ridicule and that he experienced a significant subjective hurt to feelings, aggravated by the foreseeable ‘maelstrom’.”

But the court did not accept the assertion Latham’s tweet held the meaning that Greenwich was unfit to be a member of NSW parliament due to his sexual behaviours.

O’Callaghan also did not accept Greenwich’s claim that comments made about him by Latham to the Daily Telegraph in April 2023 were defamatory.

Latham told the journalist: “When he calls someone a disgusting human being for attending a meeting in a church hall, maybe attention will turn to some of his habits.”

“Greenwich goes into schools talking to kids about being gay,” he said.

O’Callaghan ruled those comments did not hold the meaning argued by Greenwich’s lawyers, that he was “a disgusting human being who goes into school to groom children to become homosexual”.

During a two-day trial in June, Latham claimed the defamatory post was his honest opinion and a response to provocation from Greenwich.

He has admitted the tweet was crass, offensive and vulgar but denied it defamed the independent MP or ruined his reputation.

In a statement posted to Facebook on Wednesday, Greenwich said the ruling showed there was no place in Australian public life for such “Trump-style personalised attacks”.

“This victory is a major relief for me, my family, my staff, and the LGBTQ community. When Mr Latham published his tweet, my life changed forever. The tweet was, effectively, a reductionist caricature of me which caused me enormous damage,” he said.

“This judgment makes Australia a safer place for me, my community, and my parliamentary colleagues. This judgment sends a clear message that you can’t attack a gay person based on their perceived sexual activities; you can’t cross the line when it comes to personalised political attacks, and you can’t just say whatever you like online without consequence.”

The graphic post was widely criticised across the political spectrum, including by One Nation federal leader Pauline Hanson.

Before the tweet was taken down following requests by Greenwich, several responses by other users were also “liked” by Latham.

Those comments included a post that read, “About time someone didn’t hold back on what everyone really thinks about these grubs.”

NSW Premier Chris Minns said he already thought the tweet was a “horrific statement” from Latham and “that’s been proved today in court”.

The online sparring match between the two politicians followed violent protests outside a church in Sydney’s south-west, where Latham was giving a pre-election speech in March 2023.

About 250 mostly male counter-protesters violently attacked police and 15 LGBTQI protesters who had set themselves up outside the Belfield church.

The matter will return to court on September 25 for final orders.

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-with AAP