Questions around the use of anonymous sources will be raised in a defamation case between Talley's and TVNZ

The company's suing TVNZ and reporter Thomas Mead for a series of six stories in 2021 and 2022, it claims were false and harmed the company.

It's alleged substandard health and safety practices made heavy use of anonymous sources.

Herald Investigations Reporter Matt Nippert says TVNZ and Thomas Mead are defending the stories, saying they're the result of responsible journalism.

He says Mead has maintained anonymity to his sources, which means the case needs to be proved without them.