Friday's rejection of the application for Special Leave to Appeal in the High Court of Australia has left her and the members of the families of the three children murdered in Bowraville 29 years ago completely drained.

"You know I started this when I was 21 - this year I will turn 50 but I won't stop. I have my down times when I feel anxious but when I need to I will come out swinging," Michelle said.

"I need to do this to support my sister (Becca Stadhams) ... but it is so heartbreaking, I feel like I have let my niece (Evelyn Greenup) down."

She said the actual hearing before three High Court judges was bizarre.

"The court room was tiny and completely packed. The whole time the lawyers for both sides were making their presentations, there was a warning of a possible fire on the 16^th floor coming through the speakers - and we were on the 23^rd floor! 

"Then it was announced as a false alarm and then the bloke left the mic on and we could hear him breathing and chewing. It was a frigging joke!

"And when the judges left to deliberate, they weren't out for more than a few minutes before they were back with their decision ... it felt like a rush job with a foregone conclusion."

The bid for the High Court appeal was the last roll of the legal dice for the families and followed the NSW Court of Criminal Appeal ruling last September that a man could not be retried for the murders of two of the children or tried over the murder of a third.

It was the NSW Attorney-General, Mark Speakman, who lodged the appeal, saying he believed there was a chance of success.

He too was disappointed with the result.

"Despite this result, I believe that the retrial application was in the public interest ... it is clear that there were failings in the criminal justice system's initial response to the suspected murders of the children," Mr Speakman said.

"I hope that those mistakes are never repeated again. The Liberals and Nationals Government will consider options following today's decision."

Those options will include choosing to vote in favour of the bill that Greens MP, David Shoebridge, will table in parliament in the near future asking the majority of MPs to fix the double jeopardy laws.

The bill will ask that the meaning of the word 'adduce' be clarified. Mr Shoebridge said it offered a narrow but fresh gateway for the families.

"That one word is blocking us from getting justice," Michelle said.

"All we want is for the word to have the same meaning as it does in the UK ... as members of the Commonweatlh, it is strange that it is not clear here."

She said in 2013 NSW politicians movingly stood as one in the parliament in a show of support to the families, however when it came to an actual vote on this same question, that support evaporated.

"If they'd done the right thing then, we wouldn't still be here five years later. They might think this is a witch hunt but they should put themselves in our shoes - we are all related and our one big family has lost three of its children, one of whom (Colleen Walker-Craig) has never been found - just imagine the pain of that."

Spokeswoman for Clinton Speedy-Duroux's family, Leonie Duroux, said the disappointment aside, she was feeling extremely angry.

"It felt like such a big show and all so public and once again we were denied justice, and it happened so quickly ... I feel angry with the way we were treated - again," Leonie said.

Attempts to contact Colleen Walker-Craig's family have so far been unsuccessful. Their comments will be added when they are received.

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