A controversial extradition decision involving an alleged murderer could head to the Supreme Court for a new hearing.
The 10-year saga took another twist in June when the Court of Appeal ruled Justice Minister Andrew Little must address serious questions about human rights in China - including the right to a fair trial and the risk of torture.
Kyung Yup Kim, who was born in Korea but moved to New Zealand when he was 14, is accused by Chinese officials of murdering Peiyun Chen while on holiday in Shanghai in 2009.
The 99-page judgment goes so far as to direct the Justice Minister to question the diplomatic assurances given by China - including that Kim would not be tortured - given torture is already against the law in China but persists.
The decision of the Court of Appeal, written by Justice Helen Winkelmann, who has since been promoted to Chief Justice, was lauded by Kim's lawyer Dr Tony Ellis as one with "profound human rights importance which will resonate throughout the Common Law world".
At the time, Ellis said it would be difficult for the Crown to appeal the ruling as two of the three judges who issued the Court of Appeal decision - Justice Winkelmann and Justice Joe Williams - now sit on the Supreme Court.
But the Crown says the Court of Appeal made mistakes in each of the eight principle findings of its extradition decision.
Submissions filed by the Solicitor-General Una Jagose, QC, ask the Supreme Court to schedule a new appeal hearing.
She said Kim was charged with a serious crime in China and the Court of Appeal's decision establishes new legal tests for as to how the Justice Minister should approach extradition, specifically in regards to torture, fair trial rights and the use of diplomatic assurances.
These new tests would set New Zealand apart from other comparable countries, said Jagose, and affect many other extradition cases in the future.
"Extradition processes exist to ensure there can be no safe haven for those accused of very serious crimes.
"The proposed appeal concerns the right balance to be struck between upholding international human rights standards and the reciprocal obligations between states in respect of extradition of suspected offenders," wrote Jagose.
"These are matters of general or public importance which should be settled authoritatively by the Supreme Court."
In response to the Crown, Dr Ellis has filed a cross-appeal.
If a new hearing is granted, he asked the Supreme Court to not send the extradition case back to the Justice Minister - but quash the case entirely.
The Supreme Court has yet to issue a decision on whether it will hear the case.
The case is the first extradition application in New Zealand sought by China.
Kyung Yup Kim was on holiday in Shanghai in 2009 when Peiyun Chen, a 20-year-old sex worker, was found beaten and strangled.
But Kim had left for South Korea before officials sought him for questioning
China sought his extradition from New Zealand in 2011, when he was arrested and spent five years in jail, without trial, before being released on electronic bail in 2016.
During that time, his extradition was approved in 2015 by Amy Adams, the Justice Minister in the previous National-led government.
Adams agreed to send Kim to China to face trial over the murder, after Chinese officials promised he would not be tortured or executed and that his fundamental rights - such as the right to remain silent - would be protected.
But Kim successfully challenged that decision by judicial review and Justice Jillian Mallon found Adams had been too willing to take Chinese officials at their word.
Justice Mallon said there "substantial grounds for believing torture remained a real issue in China".
She ordered the minister to seek more information and reconsider her decision.
Adams again decided in 2016 to surrender Kim to China, after the Ministry of Foreign Affairs promised to check on Kim's welfare at least once every 48 hours during the investigation in Shanghai, and at least once every 15 days during the trial.
Again, Kim appealed for a judicial review.
But this time, Justice Mallon upheld Adams' decision as Justice Minister. The High Court judge noted there would be "repercussions for the bilateral relationship between China and New Zealand, and China's international reputation" if the death penalty was imposed.
This decision which was again appealed by Kim's legal team, led by human rights expert Dr Tony Ellis, to the Court of Appeal in July last year.
They argued the Justice Minister must not order someone to be surrendered under the Extradition Act if there were "substantial grounds" the person would be in danger of being tortured.
This provision reflects New Zealand's commitment to the International Convention against Torture and other international law obligations.
Other restrictions relevant to Kim's case, is New Zealand cannot surrender someone who might be sentenced to death, or there are compelling reasons which would make it "unjust or oppressive" to send them back.
The issue of whether someone would receive a fair trial is not expressly written into the Extradition Act, but the Court of Appeal said it was "common ground" - on the facts of Kim's case - the Justice Minister should consider fair trial rights in China.
This was because the Extradition Act provides for "any other reason" the Minister considers someone should not be surrendered, which the Court of Appeal interpreted should include New Zealand's obligations under international law.
"The issues on this judicial review are difficult. Mr Kim's is the first occasion on which New Zealand has been asked to extradite to the People's Republic of China.
"Extradition processes exist to ensure that those who commit crimes cannot escape consequences by fleeing the jurisdiction - that there should be no safe havens for those who commit serious crimes," the Court of Appeal wrote.
"And it is alleged that Mr Kim has committed a very serious crime, a crime in respect of which credible evidence has been gathered by the PRC.
"But on the other hand, the Minister of Justice is asked to return Mr Kim to a country that has a criminal justice system very different to our own, that has not committed to relevant international instruments in the way or to the extent that New Zealand has - a country in which, it is reliably reported, torture remains widespread ... New Zealand has obligations under international law to refuse to return a person to a jurisdiction in which they will be substantial risk of torture, or they will not receive a fair trial."