Five years of work come to a head next week for the team seeking to have Teina Pora's convictions for a 1993 rape and murder quashed by the Privy Council.
Pora, who was released on life parole this year after spending 21 years in jail for the rape and murder of Susan Burdett, will follow the London proceedings via the internet from Auckland.
A panel of four Law Lords and New Zealand's chief justice, Dame Sian Elias, will review the case on Tuesday and Wednesday.
Pora has twice been convicted of the crimes and had an appeal to the Court of Appeal dismissed.
His defence will contend that new evidence supports the claim that Pora's confessions were false.
The evidence is expert opinion on false confessions and a recent assessment that Pora is affected by foetal alcohol spectrum disorder.
The other ground of his appeal is that because of an error by his lawyer, the significance of Malcolm Rewa's erectile dysfunction was never put to a jury.
Rewa was convicted of rape but two juries could not decide whether he was guilty of murder after semen from Ms Burdett's body was found to be his.
The Crown will be represented by Solicitor-General Michael Heron, QC, Dr Mathew Downs and Zoe Hamill.
His case is likely to be the last New Zealand sends to the Privy Council, following establishment of our Supreme Court in 2004.
Judges' task
The judicial committee of the UK Privy Council is examining:
• Whether the NZ Court of Appeal was wrong to uphold a ruling that restricted evidence relating to the modus operandi of the appellant's purported co-offender, Malcolm Rewa.
• Whether the committee should admit and consider fresh evidence raised by the appellant.
• Whether a substantial miscarriage of justice was caused by the failure of the appellant's counsel to raise material points.
• The panel is: Lord Kerr (chair), Dame Sian Elias, Lord Reed, Lord Hughes, Lord Toulson