The mother of one of the miners who died in the Pike River Mine says today's Supreme Court ruling is a moral victory and will set a precedent to stop such deals taking place again.
Sonya Rockhouse, whose son Ben Rockhouse was one of 29 miners who died in November 2010 in the explosion, was one of those who took the case to the Supreme Court.
The court ruled today that WorkSafe's decision withdraw its prosecution of Pike River mine boss Peter Whittall, in exchange for payments to the victims' families, was unlawful.
Ms Rockhouse said she was in disbelief and needed time to take in the implications of the decision, but at the very least it was a moral victory.
"It will set a precedent so that in the future this can never happen again ... so [that] when charges are laid, they actually have to be followed through with.
"You can't pay an amount of money and get away with it."
Anna Osborne, whose husband Milton died in the disaster, said the ruling was "a monumental win".
"Justice should not be bought in New Zealand and this is what this is all about."
She paid tribute to late trade unionist Helen Kelly who spearheaded the legal campaign before she died in 2016.
"Helen was our battler. She saw that it [the deal] stunk," Mrs Osborne said.
The ruling, combined with the new government's pledge for a manned re-entry to the mine, made it feel like things were finally falling into place for the Pike families, she said.
"After all the crap we put up with for the last seven years ... and my man might even be coming home."
Pike River victims families' spokesperson Bernie Monk said the Supreme Court's ruling was their first real win and although they were ecstatic they would not rest until they could get into the mine's main entry.
He said he could tell that they would win by the types of questions asked at the appeal hearing by the court.
"It doesn't surprise me, but we had to go through the loops to make sure that the big corporates don't do that to the man in the streets like they've done to the Pike River families.
"I'm ecstatic, but that's the first win that we've had and the next one is to get into the drift."
Minister Responsible for Pike River Re-entry Andrew Little said while the families of the miners have been vindicated by today's Supreme Court decision, those responsible had got away scot-free.
Mr Little said Anna Osborne and Sonya Rockhouse fought their way through the court system and would feel enormously vindicated by the ruling.
"I think many of us, irrespective of the hats we wear now, looked at what happened three or four years ago and were frankly stunned."
He said the re-entry project would be the "next best form of justice", given no prosecution can take place.
"Under the Health and Safety legislation, [prosecutions] are time-barred, you have to do it within a period of time.
"Whether there are other grounds for prosecution under other legislation, including the Crimes Act, it seems pretty remote that anything further can happen.
"But I think the re-entry project at least gives us the opportunity to get in there, gather any other evidence, including forensic evidence that might be useful, and then gauge it at that time."
It was disappointing that people responsible for one of the biggest workplace tragedies have walked away scot-free, Mr Little said.
WorkSafe did not exist as an entity at the time of the explosion, but Mr Little said all government agencies would learn a lot from the ruling.
"There is a very clear standard now set, that the Supreme Court has said in the face of prosecution decisions, if big money is being waved around to try and prevent those prosecutions, that's not acceptable. Justice must run its course."
"Whether there are other grounds for prosecution under other legislation including under the Crimes Act it seems pretty remote that anything further could happen."
However, Mr Little said the Pike River re-entry project could allow for new evidence, including forensic evidence, to be gathered from the mine.
WorkSafe said it accepted the Supreme Court ruling.
Chief executive Nicole Rosie said the decision clarified the approach the regulator should have taken, and would take in the future in such circumstances.
She said she hoped the decision would bring some relief to the families and the agency would be seeking a meeting with them shortly to discuss it.
Ms Rosie said New Zealand was a safer place to work as a result of the families' commitment, with new health and safety legislation and a regulatory unit focused on hazardous jobs.