Whistleblowers 'very important' - expert
Last week Mr Snowden, a 29-year-old former contractor for the US National Security Agency, leaked documents to British newspaper The Guardian detailing the scheme, which allegedly has direct access to servers of some of the world's largest technology and internet companies.
He revealed his identity in an interview with the paper, saying he had no intention of hiding because he had "done nothing wrong".
Dr James Hollings, who did his PhD on New Zealand whistleblowers, believes Mr Snowden fits "the classic pattern of someone who just felt they had to do something".
"Usually whistleblowers, they have a strong sense of morality," he said on Firstline this morning.
"You get the occasional fringe ones who are doing it for revenge or because of a grudge, but by far the majority are moral people, they're courageous people.
"They feel that if they don't do something no one else will, and so they have to balance the ethics of loyalty to their organisation against the greater good, and that's clearly what happened with Ed Snowden."
Dr Hollings says whistleblowers are often torn between loyalty to their organisation and doing what they see as the right thing, and going public is often a last resort.
"They start to realise that no one else thinks the same way as they do."
High-profile New Zealand whistleblowers include Neil Pugmire, who in 1993 revealed a dangerous sex offender was to be released from a mental health institution. He lost his job, and the patient – convicted paedophile Barry Allan Ryder – went on to reoffend.
Mr Pugmire was later reinstated after the Employment Court ruled in his favour. Dr Hollings says the Protected Disclosures Act of 2000 is meant to stop whistleblowers from persecution, but it doesn't really work.
"Hardly anyone's using it, and that's a sign that it's not very healthy. And it's a shame really, because whistleblowers are fundamental to a healthy society, and you know, I wish we'd had someone who'd blown the whistle on what was going on at Pike River before that happened, or again, maybe some of the problems looking at buildings in Canterbury after the first earthquake.
"Whistleblowers are annoying often, but they're very important to keep our place working."
In the case of Mr Snowden, Dr Hollings says he hasn't put anyone's immediate life at risk, so in revealing the PRISM scheme has probably acted in an ethical manner.
"There are times when it's probably not ethical to blow the whistle – if you put someone's life at risk, for example, immediate lives at risk – it doesn't appear that he's done that. He's just revealed the existence of a programme, he doesn't seem to reveal specific details about individuals, from what I can tell, that would put them at risk personally.
"I think he has [acted ethically], and watching the live interview with him, he comes across as genuine and scared, but determined."
Mr Snowden has said he would be applying for asylum in Iceland, but others have suggested Russia, mainland Europe or even New Zealand could be better options.