The Supreme Court has ruled that groups can register as charities - even if they have political purpose.
A law change in 2007 meant that the environmental group had to apply to become a charity. The Charities Commission turned it down in 2010 due to the group's political agenda and perceived illegal activity. It's been fighting the decision ever since.
A Court of Appeal ruled that Greenpeace's policies against nuclear and mass destruction weapons were not controversial and shouldn't discount them from being a charity.
However, it said the group's level of political advocacy was above the level needed to achieve its aims.
In a ruling released on Wednesday afternoon, the Supreme Court said political purpose does not discount a group from being registered as a not-for-profit and and Greenpeace can now reapply to be a charity.
Greenpeace spokesperson Bunny McDiarmid said the ruling indicates a modern view of what charities are and shutting charities out from political debate is a chilling thought.
"It's not so important to get the registration - what it was important to get was the broader definition of what it means to be a charity in the 21st century. That was the purpose of the legal case or the legal marathon over the last five years."
However, Ms McDiarmid said the ruling has not cleared up what constitutes illegal activity for groups trying to register as charities.
In a statement on Wednesday, the Department of Internal Affairs is responsible for charity applications and said it would closely study the Supreme Court ruling and would not make any further comment.