In a hearing in the High Court at Auckland on Tuesday, the parties went head to head over the legal discovery of those documents – including the specific names of confidential sources who TVNZ reporter Thomas Mead spoke to, and quoted, as part of his investigation.

TVNZ and Mead personally have been named as defendants in the case.

TVNZ pushed back forcibly in court at Talley’s attempts for the broadcaster to reveal the names of sources, saying any such order would have a chilling effect on journalists’ work in dealing with matters of public interest.

“Why is this so important?” said Davey Salmon KC, acting for TVNZ, before explaining the case was happening at a time when journalism was “more important than it has been, at least in our lifetimes, and when it’s more under threat”.

Journalists, Salmon said, were “increasingly imperilled” in the world.

Whistleblowers, working with a responsible journalist, were critical in helping ”lubricate” a democracy and informing public debate, he said. Otherwise, people would simply turn to the internet, without any filters or balance. Without any journalistic safeguards, “we all suffer”.

“Secondly … this particular aspect of journalism – the promise to a source to keep their confidence – is recognised in law as being vital … but it is also sacred to journalists themselves.

“They make this promise and we know from general history that the journalists have been willing to go to prison rather than reveal their sources. It’s a vital element of their ability to do the job.

“We know it’s particularly vital when they are dealing with whistleblowers who are speaking out in a context where someone in power doesn’t want a story to be told. Someone said that’s the definition of newsworthy – that someone powerful doesn’t want the story told.”

Talley’s lawyer William Potter told the court earlier that some 145 documents had been withheld from Talley’s in the discovery process.

His argument boiled down, in many respects, to Talley’s flying blind.

He confirmed Talley’s wanted the names of sources and documents such as transcripts and other interactions between Mead and the sources to understand more of the context of their claims – and to judge how well TVNZ had tested their motivation, reliability and allegations.

Potter said the sources’ fears that they might be disadvantaged if they were identified “may well be real, but ultimately they are unfounded”.

He said undertakings had been given that if the sources’ names were released, they would be limited to only three people within Talley’s plus the company’s lawyers. The HR manager of Talley’s, said Potter, had given an assurance the sources would not be disadvantaged.

TVNZ’s position in withholding so many documents reeked of “absolutism” and a “failure to compromise”, Potter said.

He said without the documents, there was no way to understand the context of the sources’ position, their motivation and reliability and how they and TVNZ had interacted.

Before Justice Peter Andrew, Salmon suggested the best remedy might be for a direction to counsel to review again the documents and whether any could be released that did not lead to the identification of the sources.

Section 68 of the Evidence Act specifically refers to the confidentiality of journalists’ sources: “If a journalist has promised an informant not to disclose the informant’s identity, neither the journalist nor his or her employer is compellable in a civil or criminal proceeding to answer any question or produce any document that would disclose the identity of the informant or enable that identity to be discovered.”

However, the act also says a judge can make an order that overrides that if he or she is satisfied the public interest of the name outweighs any likely adverse effect on the disclosure of the informant or the public interest in the communication of facts and opinion to the public by the news media.

Salmon said there were critical principles at stake.

“The bigger issue and what the [precedent] cases speak to very clearly is that once confidence in journalistic reliability is broken, the whole thing breaks.

“So the ability to write publicly important articles that reveal points of public interest, whether they’re English cases about scandals in the medical community, political crises, or an enormous employer in a quasi-fiefdom at the top of the South Island that has an alleged health and safety issue.

“There is a recognised public interest in that being written about, and there is a recognised public interest in enabling people to safely speak to a journalist.”

Editor-at-Large Shayne Currie is one of New Zealand’s most experienced senior journalists and media leaders. He has held executive and senior editorial roles at NZME including Managing Editor, NZ Herald Editor and Herald on Sunday Editor and has a small shareholding in NZME.