Organisers of an international justice conference say they asked David Bain to speak because he is a case study of wrongful conviction.
The New Zealander was convicted of the murder in 1994 of his parents Margaret and Robin Bain and siblings, Arawa, Laniet and Stephen at their Dunedin home. He was then acquitted in a retrial in 2009 after serving 13 years in jail.
Mr Bain is a keynote speaker next weekend in Perth at a conference billed as the first to combine people who overturned guilty verdicts with legal practitioners and forensics experts.
The group Justice for Robin Bain says it is too soon for David Bain to be appearing at a conference.
Spokesperson Kent Parker says he should not appear until at least next year after a claim he is making for compensation is settled.
Mr Parker says the group has given the organisers material about the case so they know there are still major questions.
David Bain has been invited to speak by Justice Western Australia in his first public speech since his acquittal.
A conference spokesperson, Estelle Blackburn, says he will have plenty of important experiences to share.
"David Bain is coming to the conference as a person who has been wrongfully convicted, who has been exonerated through the courts and he will be presenting his case as a case study of his experience."
Mr Bain will be speaking alongside American boxer Rubin Hurricane Carter and Australian Lindy Chamberlain-Creighton who argued that a dingo killed her daughter Azaria in 1980 and won a pardon.
Ms Blackburn says David Bain was invited to speak two years ago before he lodged a compensation claim.
She says the Bain case is not well known in Australia, but important because of the way the Privy Council intervened in 2007 to correct a miscarriage of justice.
Ms Blackburn says that Kent Parker's group has been bombarding her and the organisers with information and questions.
The New Zealand Law Society's criminal law committee convenor, Jonathan Krebs, says it is unfair on David Bain for the public to keep speculating on his innocence or guilt, because there are only about 20 people in the country who have heard all the evidence.
"It's quite clear that he was convicted in one trial, but that conviction was ultimately overturned by the Privy Council and then on the same evidence at retrial - or more or less the same evidence - he was acquitted.
"So I think from that it's probably fair to say that he was wrongfully convicted on the first occasion."
Mr Krebs says he knows there is public unease about the final outcome of all the Bain cases - but it is for David Bain to decide when is the right time to talk about it.
Bain gives first major interview
On Sunday night, David Bain gave his first major news interview since his acquittal and reasserted his innocence.
Mr Bain told TV3's 60 Minutes that he considered committing suicide in prison but his faith in his innocence kept him from that.
He said he refused to do special rehabilitation programmes because they would have required him to admit his guilt.
The interview avoided any discussion of the evidence presented at his retrial and did not ask why he did not take the stand himself.
