Police did not use the Army's light armoured vehicles to smash into gunman Jan Molenaar's house because of uncertainty about whether they had the legal authority.
Defence Minister Wayne Mapp said that although it seemed logical to smash in, the interpretation of the law by police and the Defence Force
meant they were reluctant to use the LAVs for anything more than protected transport during the siege.
Dr Mapp has asked for a report to clarify the law so the police use of defence assets can be made easier in future.
Two LAVs were used during the siege with police emphasising they were under their control with only the Army's drivers used.
The LAVs went up to the front of Molenaar's house, a two-storied property with a garage underneath.
Dr Mapp said the police were concerned if they had the legal authority to "take the next step" and push against the garage door. In the end, they did not.
He said the interpretation of the relevant part of the Defence Act was that there was no difficulty in using defence assets in support, such as transport, but it was unclear how far they could go in using them for a police task.
"There was a question whether they could use the LAV to push against the garage door."
Dr Mapp said it was his understanding that police did not fire tear gas into the house from the safety of inside the LAV. He said the tear gas was fired by police standing beside the LAVs.
During the siege, police said they used explosives to blow their way into Molenaar's house. Dr Mapp said "common sense prevailed" when a LAV was used to move a car outside.
He said the use of the LAV raised the question of whether police needed their own armoured vehicles, although it was convenient enough for them to borrow from the Waiouru base.
Dr Mapp said the lending of the LAVs had required considerable top-level discussions between himself, Minister of Police Judith Collins, the police and the Defence Force. He requested the report clarify how Army assets could be used so there were no such limitations in the future.
