It was sparked by a leak to the media in 2017 about Peters being overpaid $18,000 in superannuation.
The overpayment was accidental, and Peters repaid it immediately. It occurred because he did not tick a box about having a partner.
Following on from the leak, Peters took the public servants and two National MPs - who had been ministers at the time - to the High Court, claiming his privacy had been breached.
In the judgment which was released in April 2020, Justice Venning agreed there was a breach of his privacy.
He also said Peters could not establish that any of the defendants were responsible for the leak, and ordered Peters to pay court costs.
Justices French, Goddard and Collins presided over the appeal.
During the hearing Peters' lawyer Brian Henry focused on the fact that ministers were told about the case in the first place.
He said breaches of privacy occurred when the top officials - former Ministry of Social Development (MSD) chief executive Brendan Boyle and the State Services Commissioner Peter Hughes - briefed their respective ministers Anne Tolley and Paula Bennett about what had happened.
Henry said that personal information should never have been divulged.
He told the court all New Zealanders were entitled to that guarantee of privacy, and only in the case of fraud should ministers be given the identity of individuals.
Victoria Casey, on behalf of MSD, rejected this, saying that public servants wanted to be able to prove Peters had not been granted special treatment because of his status and power.
Casey criticised the plaintiff for not bringing up this argument in the initial High Court case.
Today's judgment found Peters did have a reasonable expectation the details would be kept from the media, but not that it would not be shared within MSD or to the relevant ministers.
It found the chief executives of MSD and the State Services Commissioner had reason to be provided the information and that they had immunity from liability under section 86 of the State Sector Act.
MSD was also not liable for the information being shared with the media because it was not the only agency that held the information, and no direct link could be established between the ministry and the media.
"As a matter of logic the leak could have come from a number of sources. MSD is not liable for the unlawful disclosures made by an unknown person merely because it was the original holder of the information, which had subsequently been provided (lawfully) to a number of people inside and outside MSD," the judges found.
