Opening statements by both parties in the Peter Ellis appeal have been given today in the Supreme Court.
The country's highest court is hearing the appeal against sexual abuse convictions for the former crèche worker, who died in September 2019.
Ellis's lawyer Rob Harrison told the court the appeal would focus on four issues.
"The first ground really looks at the complainants' testimony, the risk of contamination.
"We say that they were under-estimated due to the absence of scientific knowledge at the time, and that improper techniques were used to obtain the evidence from the child complainants."
The second was to do with expert testimony by psychiatrists.
"The jury were not appropriately assisted by the expert testimony when determining whether the complainants' testimony was reliable.
"Without proper instruction from an appropriate expert, the jury could not decipher the evidence in a way that would allow them to reach a just decision."
The third ground was to do with evidence which apparently showed symptoms shown by children, in which an expert witness testified was linked to abuse.
"We argue that the evidence was really without scientific foundation... [and] that the advantage given to the prosecution by that sort of evidence that did not have a scientific basis was inherently unfair and led to a miscarriage of justice."
The final ground was the appellants' argument that the trial was inconsistent with the New Zealand Bill of Rights Act.
"The trial was unfair, due to the sanitisation of the charges that were advanced against Mr Ellis - the failure to present all of the children's interviews to the jury and the failure to provide the jury with all the necessary jury materials."
Lawyer for the Crown John Billington QC said parents talking to their children and giving children access to resources to help them cope was necessary and should not mean their testimony was any less reliable.
"The need for the child to be interviewed only arises usually when some relevant information has been given to the parent or to another carer.
"These are little children whose parents love them and have to support them. It is unreal to suggest that that sort of conduct as between parent and child somehow is a factor that contaminates that evidence so as to disregard it totally."
image_crop:131403:full] John Billington QC at the Supreme Court hearing.
He said previous courts had ruled correctly that Ellis was guilty based on the "totality of the evidence".
"Because the parents were also cross examined on the same material. Those who conducted the interviews were cross examined on the same material. Parents [and staff] gave evidence about the conduct of the accused at the crèche."
Clinical psychologists, scientists and memory experts will be heard from over the course of the trial which is set down for two weeks.