Serco insists the company's not taking the Corrections Department to court over the Chief Inspector's report into fight clubs at the Mount Eden prison to avoid criticism.
The private prison operator is seeking judicial review saying the report is unreasonable after footage of violent attacks on prisoners emerged online last year.
Serco says the terms of reference of the investigation changed.
Their lawyer, Hayden Wilson, told the High Court in Wellington that the Chief Inspector was originally looking into organised fights at the prison.
However, he claims the terms of reference became more wide-ranging and looking into management and not just the alleged fights.
Mr Wilson also says Corrections refused to give them access to anonymous interviews conducted as part of the investigation.
Serco also says the report is unreasonable.
The hearing is expected to wrap up tomorrow.