Slater counter-sued Craig for what he said in the pamphlet and at the press conference.
In a more than 200-page judgment released in 2018, Justice Kit Toogood ruled Slater had defamed Craig, but declined to award damages.
The judge said Craig "was guilty of moderately serious sexual harassment" against MacGregor "on multiple occasions from early 2012 to 2014".
Just two days before the 2014 election MacGregor spectacularly quit as press secretary and later filed a sexual harassment complaint against Craig.
In the Court of Appeal in Wellington today, Slater's lawyer, William Akel, said the judge was right not to order Slater to pay damages.
He said the alternative was to pay "a pittance" to Craig, which would be "worse" for him.
Akel also said the judge "saw, listened, and evaluated" Slater and "concluded that he's not a compulsive liar, that he does try and uphold standards of balance and accuracy".
On the issue of Slater's claims that Craig made a "six figure" payment to keep the sexual harassment a secret, Akel said Slater had sources, but no sources were perfect.
But Justice Stephen Kos said Slater should have stuck to "documents" to support that claim instead of relying on sources' words.
He said the defamatory claims came at a time they could have "affected the structure of the National government", and could have made the difference in whether the Conservative Party received five per cent on election day.
Justice Toogood had ruled Slater defamed Craig with the untrue statements Craig had placed MacGregor under financial pressure to sleep with him and had sexually harassed at least one victim other than MacGregor.
Other false allegations included the claims Craig had sent sexually explicit text messages, paid a six-figure sum to settle a sexual harassment claim, and sexually harassed two or more women.
But, Justice Toogood said: "I have also held that the reputational damage which Mr Craig suffered throughout the events traversed at length in this judgment resulted almost entirely from his own actions.
"I conclude, therefore, that Mr Craig is not entitled to an award of general damages to compensate him further for such damage."
The court has reserved its decision.