Labour and the Greens have strongly condemned the Prime Minister's latest statement on how he plans to grant interception warrants under the new GCSB law.
Labour leader David Shearer and Greens co-leader Russel Norman say his new policy should be written into the law itself - which is due to be passed next week - and New Zealanders should not have to take his assurances on trust.
In a major concession, Mr Key has decided that he will restrict interception warrants of the spy agency when acting under their cyber security function.
He says he will make it a condition of the warrant that they not look at the content of communications, the Prime Minister's spokesman said in a written statement to the Herald.
"If a serious cyber intrusion were detected against a New Zealander, the Prime Minister would require the GCSB to return and make the case for a new warrant to access content itself, but only where the content was relevant to the threat."
Mr Shearer said it was not good enough to make such pronouncements through the media.
"What on Earth is the legal status of John Key's email to the media?"
"The Prime Minister is essentially asking New Zealanders to trust him. He is telling the public he won't let the GCSB use the powers the new law grants them, except in exceptional circumstances."
He said New Zealanders should not have to take the protection of their privacy on trust.
"If John Key is serious about protecting Kiwis' emails, he should change the bill so that it does just that."
Mr Key issued his statement to the Herald after it pointed out that Mr Key had incorrectly stated on TV3's Campbell Live on Wednesday that the GCSB would not be able to look at the content of New Zealanders' communications.
He then said explained that that was the way he intended to operate warrants under the cyber security function.
The Greens called Mr Key's new policy a "backtrack."
"After claiming on Campbell Live that the GCSB would not be able to look at the content of communication as a part of the agency's cyber security function, John Key has now had to backtrack and acknowledge that there is nothing in the bill preventing that," Dr Norman said.
Mr Key's assurances that he won't allow the GCSB to spy on New Zealanders' emails without good reason needed to be spelt out in the law and not left up to an individual's judgment.
"That is not how good law is made."
He said that is making the statement on Campbell Live either Mr Key had not understood his own bill or he had purposely misled people about it.
"At least by being forced to make assurances, John Key is finally acknowledging that New Zealanders do not want to be spied on. "
Under the bill, the GCSB will have three functions. The first is its traditional one of collecting foreign intelligence, and it is not allowed to spy on New Zealanders under that function, either currently or in the future.
The second will be in assisting the SIS, the police and Defence in conducting duly warranted interceptions of New Zealanders. It has been doing this already under dubious legal authority, because while the current law says it can help such agencies, it explicitly says it cannot spy on New Zealanders.
The real expansion comes under its cyber-security function. Until now its cyber-security function job has been to protect Government communications only from attack, but it will be extended to private-sector cyber systems if they are important enough to New Zealand.
HOW IT WOULD WORK
Cyber security today: Under the present law, if the GCSB detected an intrusion into the IRD cyber system, it could track its source if it were overseas, or if it were from the computer of a foreigner in NZ but not if it were from the computer of a Kiwi.
Cyber security tomorrow: Under the proposed law, if the GCSB detected an intrusion into the IRD cyber system it could track its source whether abroad, without a warrant, or in NZ with a warrant, which John Key says would not access the communications' content. If the Kiwi's computer was suspected as being an unwitting host of a remote attacker abroad, the GCSB would alert the Kiwi to get permission to access his or her computer content. If a person was suspected of being involved in the attack, the GCSB would get a warrant to look at the content.