Greenpeace New Zealand is facing a battle, after the introduction of new rules around tax breaks.
A recent ruling concluded that organisations that do not officially have charity status are not entitled to tax breaks.
But now there is a call to relax the rules.
Greenpeace New Zealand has been operating for 35 years and says its work campaigning for peace and the environment means it should qualify as a charity.
But the Charities Commission says Greenpeace is too politically involved to meet its criteria.
Charities Commission Chief Executive Trevor Garrett said the law appears to be quite clear "and we simply follow that law".
But Greenpeace Executive Director Bunny McDiarmid said there is not a really clear line about how much is too much political advocacy and how much is too little.
"I would argue that most of the charities that have got charitable status are very much engaged in change they want to see, positive change for our society today."
It is not just a war of words, big money is involved.
The Charities Commission was set up six years ago and given the power to decide which organisations should be registered as charities and which should not.
A registered charity does not have to pay income tax and those donating to it are eligible for a tax rebate.
So far, the commission has registered around 26,000 charities. But some high profile groups like Greenpeace have missed out and others have been deregistered, including the Queenstown Community Housing Trust, the Computer Society, and the National Council of Women.
David McCartney of Community Housing Aotearoa said there is also a credibility element to being registered.
"If an organisation is not registered on the Charities Register, they are definitely less likely to get donations and funding from other sources," he said.
And that has sparked concerns over the way the commission is applying the law.
"There are arguments that can be made that at the present point in time the Charities Commission is taking quite a strict technical, narrow view," said Susan Barker, a public law expert.
The commission disagrees.
"What we do is we look at the legislation, we look at all of the case law, and we look at the rules and activities of an organisation. Most organisations get through it," said Garrett.
Some charities are putting pressure on the Government for an urgent law change, but a review is not due to be completed for another four years.
Community and Voluntary Sector Minister Tariana Turia said the review cannot be done any sooner.
"One of the difficulties in doing it sooner than that is that we already have the Law Commission who are carrying out a review of charitable trusts. And that of course would impact on this particular review so it's really important that we align what we're doing."
Barker said there is a case for holding up the review on that basis, but it is outweighed by the concern that is being expressed in the sector and the very real impact that it's having.
"As a matter of priority it has to be brought forward."
Greenpeace took their case to the High Court which upheld the commission's decision.
Greenpeace is now planning to appeal, in a case that other groups will be keeping a close eye on.