Former Conservative Party leader Colin Craig says he is "very, very, surprised and disappointed", after a jury found he did defame Taxpayers' Union founder Jordan Williams.
His lawyers said immediately after the decision was announced they would appeal the verdict.
Mr Williams has been awarded $1.27 million in damages, after a jury deliberating for close to ten hours.
That's comprised of $1.05 million in general damages, plus $220,000 in punitive damages.
"Mr Craig's false accusations and public threats to sue me could not go unanswered," Mr Williams said outside court.
"Of course I am happy the jury - having heard all of the evidence, and not just what the media has reported - have made such a finding."
He promised new material would be released on Monday on Mr Craig and his former press secretary Rachel MacGregor.
The verdict brings to an end almost four weeks of dramatic and often lurid evidence, ranging from the identity of Mr X to the literary merits of Mr Craig's poems and the precise details of an election night clinch.
The jury had to decide if they believed Mr Williams' or Mr Craig's version of his relationship with Ms MacGregor.
The stakes were high because Mr Craig had accused Mr Williams of dishonesty in a leaflet called Dirty Politics, which he sent to 1.6 million homes.
In short, it was suggested he called Mr Williams a liar.
Mr Williams sued for defamation because the leaflet damaged his reputation. Part of Mr Craig's defence was everything in it was true and his honestly held opinion.
Only one person could prove either case - Ms MacGregor herself
"I consider Rachel to be like a sister to me, although I accept my affection went too far on occasions," Mr Craig said during the trial.
Mr Craig had kissed Ms MacGregor on election night 2011, but she said he turned into a douchebag, sending unwanted poems, cards and texts.
He said Ms MacGregor returned his affection and had texts he said proved it.
But Ms MacGregor hadn't been paid for months, and quit on the eve of the 2014 election. She later settled a sexual harassment and pay claim against Mr Craig, and it could have ended there.
But Mr Craig breached confidentiality a dozen times, most notoriously in an infamous sauna interview with David Farrier on TV3.
Worse for Ms MacGregor, she had also confided in Mr Williams, who went behind her back and showed Mr Craig's unwanted communications and poetry to the Conservative Party board and blogger Cameron Slater, also known as Whale Oil.
Mr Williams said he only did it to stand up for Ms MacGregor.
"She had settled a claim in sexual harassment, was completely silenced by Mr Craig and now he was out there breaching their agreement," Mr Williams said.
After that, the Conservative Party imploded. Mr Craig stood, down but fought back with the Dirty Politics leaflet, which accused Mr Williams, Mr Slater and Mr Stringer of being dishonest about the MacGregor-Craig relationship.
In the leaflet Mr Craig threatened to sue Mr Williams, but Mr Williams beat him to the punch. Mr Craig, Mr Slater and Mr Stringer are still suing each other for millions - which means as these men resort to the courts to protect their reputations, Ms MacGregor may be called on to relive the sorry saga over and over again.
Newshub.
