Hit and Run author Nicky Hager says the defence force failed to investigate a raid in Afghanistan, despite an Initial Assessment Team of it finding there should be an investigation.
The US military investigated its part in the raid, but the New Zealand Defence Force kepts its part in it secret, Hager said.
Hager was speaking today at the third public hearing of the inquiry into a raid in Afghanistan.
It was sparked by the book written by Hager and Jon Stephenson, which alleged that six civilians were killed in Afghanistan during a New Zealand-led raid in 2010, and the military covered up what happened.
Today's hearing looked at the legal issues the inquiry will need to consider.
The legal issues discussed relate to the context in which the attack was carried out, and the legal responsibility and implications of New Zealand soldiers alleged to have handed a Taliban insurgent, Qari Miraj, over to Afghan authorities, who are said to have tortured him.
Legal expert Sir Kenneth Keith referred the hearing to the principles that applied in such a conflict, there must be a distinction made between civilian and combatant, and civilians not attacked, but only if it was not considered excessive to the military advantage expected.
Sir Kenneth referred to parts of international conventions that stated state parties in all circumstances must respect conventions around torture.
The hearing heard about an agreement between New Zealand and Afghan authorities, that said Afghan authorities were responsible for looking after people transferred to them in accordance with international and domestic law.
Both countries were also parties to a convention against torture which meant no state should hand over a person to another state, if there were substantial grounds for believing he could be subjected to torture.
In a submission presented by Paul Rishworth QC, Crown agencies said there was no evidence New Zealand had knowledge Afghani security forces planned to torture the insurgent, and that there was no evidence people detained were being routinely tortured.
However, questions were raised by Chair Terence Arnold, who said it was known that there was systemic torture at the facility the insurgent was taken to.
Hager said legal advice given to the Ministry of Foreign Affairs in regards to the torture was outlined in a document that said New Zealand legal obligations were clear, and only extended to people held by New Zealand forces.
However the Defence Minister at the time, Wayne Mapp, had written in the margins he disagreed, and the rules were not clear.
The hearing will continue on Tuesday when the the Joint Prioritised Effects List (JPEL) that was in use for Operation Burnham will be discussed.