However, this third function is a recent fiction. It would allow GCSB to offer its intrusive technologies and specialist skills to other government departments. Or even worse, GCSB would enable other departments to obtain those capabilities for their own purposes.
New Zealanders may well accept the need for their government to possess these capabilities, but only for use in the pursuit of national security and only against foreigners. To share these capabilities with agencies charged with routine law enforcement is to abuse that acceptance.
Part of the problem is that there is no agreed meaning of national security.
The NZSIS Act 1969 focuses on protecting the state from threats of espionage, sabotage and subversion, with terrorism a more recent addition. The GCSB Act 2003 encompasses New Zealand's international and economic wellbeing, the Government's international relations, obligations and commitments, and the protection of its official communications, information systems and computer systems.
Meanwhile, the Prime Minister's Department places New Zealanders at the heart of national security, which is "the condition which permits the citizens of a state to go about their daily business confidently free from fear and able to make the most of opportunities to advance their way of life".
Without an agreed meaning of national security, our spies will set their own collection priorities.
Previously, it was the job of the Foreign Intelligence Requirements Committee to provide a statement of New Zealand's intelligence requirements. Without justification or explanation, this consensus-based approach has been dropped in favour of a hubs-and-spokes process. Government departments now each submit "Requests for Information" which GCSB then considers on a case-by-case basis.
When the concept of national security becomes this elastic, there is little to prevent the Prime Minister from directing our spies to target opposition parties or other groups as part of the Government's dog-whistle politics.
Secrecy and spin do not mix well together.
John Key's overall handling of questions concerning our spies - including his own knowledge of the Dotcom debacle, Ian Fletcher's appointment as GCSB director, and the Kitteridge Report's leak - highlights his mastery over the dark arts of spin. He's expert at reassuring New Zealanders that he's in control, that they should relax and that there's nothing untoward to see here.
On questions concerning our spies, John Key has added a reliance on secrecy to his arsenal of spin tactics. While the Prime Minister previously commented publicly on intelligence matters, such as when he boasted that New Zealand gained greater access to Australian intelligence on boat people, he now refrains.
Prime ministers have generally observed a convention of remaining silent on matters relating to our spies. And for good reason: intelligence agencies need to protect their sources and information-gathering methods since exposure would enable targets to adopt new modus operandi to avoid detection, surveillance or action.
John Key favours secrecy over transparency less for our spies' benefit and more for his political convenience. No less than his credibility and integrity are at stake here.
Given that most New Zealanders remain unaware of what spies do in their name with their highly intrusive information-gathering methods, a higher than usual standard of ministerial accountability is required. That the GCSB trampled on New Zealanders' privacy means that John Key must, as the minister responsible, immediately right this wrong. Instead, the Prime Minister apologised to Kim Dotcom before proposing an amendment bill that will further loosen controls over our spies.
In circumstances like these, nothing short of a full, independent inquiry will restore public confidence in New Zealand's intelligence community.
Dr Damien Rogers is a lecturer within the Politics Programme at Massey University, Auckland.
