Charges laid against 13 people following the 2007 police raids in Te Urewera National Park over alleged military-style training camps were dropped because officers used illegal methods to gather evidence.
The Crown dropped the charges under the Arms Act charges on 12 September after the Supreme Court ruled on that certain evidence could not be used. Suppression of the court's reasons for excluding the evidence was lifted on Friday.
Chief Justice Sian Elias found that filming using hidden cameras for over 10 months was illegal and a serious intrusion on rights.
Justice Elias says police trespassed land owned by Maori iwi Tuhoe to obtain evidence, and the covert filming also constituted unreasonable search and seizure breaching the Bill of Rights Act.
The judge says the fact police knew they were breaching human rights and continued to do so was a significantly exacerbating factor.
Police want law change
Police want a law change to allow them to continue carrying out covert surveillance. They say they believed they were acting within the law when they filmed activities on the private land using hidden cameras.
Assistant police commissioner Malcolm Burgess told Radio New Zealand's Checkpoint programme that, while Parliament has not authorised police to carry out covert surveillance, the common law understanding is that it is acceptable - providing officers do not act unlawfully.
"That's certainly the position that we understood and that was the criteria, I guess, that we have operated on until the Supreme Court made their judgement."
Mr Burgess says police are now unlikely to use covert video surveillance as often.
"The court indicates specific circumstances where covert surveillance could not be used and to do so now would be to act in bad faith. We won't be doing that. There may well be other circumstances which we'll have to carefully assess where covert surveillance is still an appropriate technique."
Mr Burgess hopes a law change allowing covert surveillance is being considered.
Calls for all charges to be dropped
A lawyer who represented a person targeted during the raids says police knew it was not lawful for them to film suspects.
Annette Sykes told Radio New Zealand's Checkpoint programme on Friday it was disturbing that police went ahead with the filming when they knew it was illegal.
Ms Sykes says she would like to all of the accused to be discharged.
Waiariki MP Te Ururoa Flavell says the Supreme Court ruling vindicates the anger and disbelief felt by Tuhoe over the raids.
Mr Flavell says charges against the remaining accused should also be dropped, given the illegal police tactics and hurt caused.
He believes the raids have damaged the relationship between police and Tuhoe, and police and Maori in general.
Kahungunu Barron-Afeaki defended one of the accused, Tuhoe Lambert, who died in July this year, and says police acted arrogantly and the assumptions they based the operation on were wrong.
Mr Barron-Afeaki says the Supreme Court's ruling backs up the accuseds' defence that no crimes were committed.
Four still face charges
Charges against four of the original 17 accused have not been dropped because the Evidence Act allows for evidence obtained unlawfully to be used if the seriousness of the alleged crime justifies the action.
A revised indictment sheet was made public on Thursday, at the defence's request. In it, the Crown says the group had a general intent to commit murder, arson, endangering public transport, using a firearm against police and kidnapping.
The Crown says even though there were no specific targets, the accused had a general intention to commit those offences as members of an organised criminal group.
Crown solicitor Ross Burns says he is confident there is enough evidence to prove that the accused had some very serious criminal intentions including murder, arson and kidnapping.