The Privy Council in London says a decision in the case of Teina Pora will be announced next Tuesday.
Pora served 21 years in prison for the 1992 rape and murder of Susan Burdett, crimes he said he never committed.
The Privy Council's website says the court's ruling will be delivered on 3 March at 10pm New Zealand time.
The 39-year-old spent over half his life in prison but had always maintained his innocence.
At the hearing in November last year Pora's legal team headed by Jonathan Krebs said new evidence showed Pora was born with fetal alcohol spectrum disorder and had a mental age of 10 when he was interviewed by police.
He said the condition meant Pora had a drive to please people and could explain why he confessed to doing something he didn't do.
Mr Krebs said there were also inconsistencies in what Pora told police soon after the murder.
He said Pora had given numerous explanations of how he and other offenders had got inside Ms Burdett's South Auckland unit.
"The position was ultimately reached after various and multiple descriptions of three offenders going through a window, going through a sliding door, going through a door, one offender through a window and so-forth," said Mr Krebs.
Mr Krebs said Pora also spoke of turning a knob on a door, but a photo of the door showed it was necessary to turn a lever as-well, which he had never mentioned.
The Crown, represented by the Solicitor General Michael Heron QC said a jury would still convict Pora, despite the new evidence.
Mr Heron QC said suggestibility could go both ways and made reference to evidence that linked serial rapist Malcolm Rewa to the case.
Rewa was convicted of 24 sexual attacks, including one on Ms Burdett.
"The Crown case is that he, led by older men, in particular Mr Rewa, took place in a criminal enterprise that ended in murder," said Mr Heron.
Mr Heron said Pora had accepted that he was exploited by the Mongrel Mob and that new expert evidence, when put in context, would have little impact
Crown lawyer Mathew Downs also addressed the defence argument that serial rapist Rewa would have acted alone when he attacked Ms Burdett because he had erectile dysfunction and would have been embarrassed.
Dr Downs said while the defence case was that Rewa covered the faces of his victims because he was embarrassed about his condition, evidence showed Rewa did this to protect his identity.
Rewa's DNA was found at the scene and Dr Downs said he was a confident offender who attacked 27 women over eight and-a-half years.
Pora was granted parole last year.