The man convicted of murdering Grace Millane acted inexcusably after her death but the trial that found him guilty was flawed, an appeal has heard today.

His legal team have argued that the jury was not properly directed when it came to considering the issue of consent - nor were they equipped to properly analyse expert evidence.

And they say errors were made in the 17-year sentence handed down, making it too harsh and unjust.

In February, the man, who has name suppression, was sentenced to life in prison with a minimum period of 17 years for murdering the British backpacker in an Auckland hotel room.

The Crown had argued the killer strangled Millane to death. His lawyers claimed the death was an accident which happened during rough sex.

Today's hearing is being heard in the Court of Appeal at Auckland before Justice Stephen Kos, Justice Mark Cooper and Justice Patricia Courtney.

The appeal is against both the conviction itself and the sentence.

Defence lawyer Rachael Reed, QC, opened the appeal by saying that while her client had a right to the hearing, she would not be trying to justify his actions.

"I do not in any way seek to condone or excuse his actions after Miss Millane's death," she said.

"I cannot and will not do so - they are inexcusable.

"This appeal is about whether the trial process miscarried."

Millane's murderer is present for the appeal via an audio-visual link from prison.

His father and other family members are in the public gallery, along with the police who led the investigation into Millane's disappearance and murder - Detective Inspector Scott Beard and Detective Senior Sergeant Greg Brand.

Millane, who had been travelling the world, met her killer on the dating app Tinder before they shared drinks at a few bars on the eve of her 22nd birthday in December 2018.

CCTV showed the pair appeared to be enjoying each others' company as they returned to his small downtown Auckland apartment.

But the university graduate would never leave the room alive - her body later found dumped in a shallow grave in the Waitākere Ranges.

After hearing from nearly 40 witnesses during the highly charged and emotional trial, the jury's decision was unanimous.

The murderer, who still cannot be named, walks into the dock during his High Court trial in November. Photo / Michael Craig

The appeal against conviction

Today Reed questioned whether the jury had the right information before them to make that decision.

She said there were four grounds to the appeal, set out in lengthy submissions.

The first was around the question trail provided to the jury for deliberations - the document they use to work their way to a verdict.

Reed said there was an issue around what the jury were told about the killer's "honest belief in consent".

She said the jury "didn't have the opportunity" to deal with the killer's "honest belief in consent" and "didn't concentrate on that very crucial time" when Millane became unconscious.

"Whether the [killer] continued to have an honest belief in consent ... The jury were not able to engage in it on the question trail."

Reed said had the jury been able to directly consider that, they may not have agreed the killer meted out the "reckless violence" needed to reach the threshold for a murder conviction.

The second point was whether the killer had time to "form a reckless intent" between putting his hands on Millane's neck and her dying - particularly if he had an honest belief she had consented to the act.

Reed was not suggesting the belief of consent was a defence to murder.

Just that the jury should have had more in-depth consideration of whether the belief in consent was genuine and if so - that removed the recklessness of the violence to Millane and the culpability of the killer.

Her client's "state of mind" and "conscious appreciation" of the situation Millane was in were not inserted into the question trail adequately, she submitted.

Reed said tweaks to the question trail would have made a practical difference to the trial result.

The jury would have "engaged" more with consent and may have concluded that the killer believe that Millane was still consenting when she became unconscious.

"And he didn't turn his mind to the risks of carrying on in those circumstances and that (death) was a reasonable possibility,' she said.

Reed said jurors were "ordinary members of the public" who did not have the background or expertise around expert evidence.

As such they should have been directed very specifically about what they needed to look at and consider.

She submitted that Justice Simon Moore should have taken more care to give a "more balanced" direction on the expert evidence.

During the man's sentencing, Millane's mum Gillian said her kind and intelligent daughter's dream to travel the world had turned into a nightmare that ripped the family apart.

"She died terrified and alone in a room with you ... all her dreams and aspirations taken," Gillian Millane said in a victim impact statement.

Justice Simon Moore said this was not a case where the strangulation was driven by rage or was premeditated.

The killer's legal team also appealed on the propensity evidence presented at trial.

They said the evidence - based on other women who had engaged sexually with the killer before he met Millane - was negative and tainted the jury's view of him.

And they said some of the evidence "wasn't relevant" and the testimony of at least one witness was "heavily disputed".

As a result of the evidence being put to the jury - the risk to a miscarriage of justice was high.

The appeal against sentence

Reed said what her client did to Millane - including taking intimate photos of her, likely after her death - was reprehensible and inexcusable.

However, when the murder itself was considered, the sentence was manifestly unjust.
Reed said there was no evidence excessive violence was used against Millane.

There was no evidence that she struggled or any bruising or injury to suggest she fought back against her killer.

At sentencing Justice Moore placed too much weight on the callousness of the killer's post-death actions and Millane's vulnerability.

"The post death conduct is certainly at times… abhorrent. What we do need to look at though is what connection that has to the state of mind he had at the time of the murder," she said.

She said the post death conduct did not show that at the exact time he killed Millane, he was being callous.

"We don't know at what time Miss Millane died so we don't know at what time the internet searches were done or the photographs were taken.

"He may have used those searches as a distasteful distraction from Miss Millane's death."

"Is there a narrative that is available that a person has realised the death of Miss Millane, become horrified about what they have done and sought to distract themselves in a distasteful way…. And then done the abhorrent act of taking photographs."

None of that though went near proving a level of callousness existed before and during the murder.

"We don't have the level of planning… or clear intent and internet searches before… this is not one of those cases," said Reed.

"They appeared to be friendly and engaging beforehand… up to that point where circumstances changed, there was no callousness."

She reiterated that her client did not plan or intend to kill Millane.

She said what a person did to "cover up" a killing may be callous - but that did not mean they were being callous when the actual death occurred.

There was no high level of callousness and thus Justice Moore should not have imposed such a high minimum non-parole period.

Reed said the ultimate minimum non parole period for her client, should have been in "a much lower range" and should be adjusted to 12 years.

But Millane was vulnerable and appeared to be restrained, he said, while the 28-year-old killer's actions in photographing her naked body after the murder were "depraved".

"You were in a position of total physical dominance," the judge told the killer during sentencing.

"You were a stranger, she trusted you."

- text by Anna Leask, NZ Herald