Ellis spent nearly 30 years battling his controversial convictions, and now his lawyers say tikanga Māori values indicate the fight should continue despite his death to uphold his mana.
The courthouse in Wellington was overflowing with members of the public showing up to hear the arguments this morning, with people packing into waiting areas as the main public gallery filled up.
Ellis, who was 61 at the time of his death, was convicted after a trial in the High Court at Christchurch in 1993 of 16 counts of sexual offending.
The convictions, based on bizarre claims of satanic rituals, torture and sacrifice, have long been controversial due to failures in the investigation and justice processes used.
Ellis was released from prison in 2000, after serving seven years for abusing seven children at the Christchurch Civic Childcare Centre in 1991.
In his application for leave to appeal to the Supreme Court, Ellis said the complainant interviews fell far short of best practice - even at the time of the alleged offending - and there was a strong possibility of contamination of the evidence.
He also argued the jury was not appropriately assisted at the trial by the expert witnesses.
The case came to the Supreme Court last year for arguments on whether an appeal should be allowed to go ahead now that Ellis was dead, but the matter was put off to today for lawyers to prepare further submissions on whether tikanga should be taken into account.
"In a tikanga context the death not only is not irrelevant ... but an ancestor has even more reputation to protect - is more tapu, has more mana. So the Māori perspective on this I would have thought would be opposite to the anglo perspective," Justice Joe Williams said at the time.
The comments were in response to arguments from Solicitor General Una Jagose that Ellis' interests died along with him, and there was no exceptional reason to continue the case.
In court this morning, Ellis' lawyer Natalie Coates said both Māori and Pākehā had mana.
"Mana and the importance of seeking to restore and uphold mana is something that transcends death," she said.
Justice Terene Arnold questioned whether adopting tikanga values in this case created a "dissonance and discord" with other cases in New Zealand, such as the fact defamation proceedings could not be continued after the death of the defamed person.
Coates said tikanga was "relevant in developing general law", and that it might be appropriate to "reconsider" other cases such as defamation.
Tikanga required the matter to go through further probing and bring the "wrong" that had happened to a state of "ea" or "finality".
Jagose said the case was already in a state of ea before the court granted leave to appeal.
Now if further probing was required, the process of deciding whether the appeal should go ahead was enough probing to satisfy tikanga values, she said.
"Mass hysteria" follow claims of children being hung in cages
Ellis has always maintained his innocence and the verdicts in his trial have remained contentious - they have been described as being the result of mass hysteria in the book A City Possessed by Lynley Hood.
Hood criticised the convictions as a "witch hunt" at a time when hysteria around child abuse was sweeping the nation.
The original 16 charges were based on the preschoolers' testimony of satanic ritual abuse and torture.
Some of the more bizarre allegations included claims the children were made to strip and dance naked and were hung in cages.
Other allegations made by the children included having their genitals cut off, having sticks inserted into their bottoms, needles inserted into them, being placed in coffins, taking part in ritual killings and taking part in mock marriages.
Children also said they were forced to eat faeces and kick each other in the genitals as adults stood around them in a circle playing guitars.
There has been heavy criticism of the interviewing techniques used with the children.
Three convictions were overturned in 1994 after one of the children said she lied, but a second appeal against the remaining 13 convictions was dismissed in 1999.
After the second Court of Appeal decision there was a ministerial inquiry in 2001 by Sir Thomas Eichelbaum, which concluded there was no risk of a miscarriage of justice.
There have also been unsuccessful petitions to Parliament for a royal commission in 2003, 2008 and 2014.
Ellis died from cancer in September, and a Supreme Court hearing was held late last year to decide whether his case could proceed.
