Kupec, who picked up the suitcases in Bangkok for $US5000 ($8000), was sentenced to 17 years in jail with no parole for eight and a half years.
At his trial, he claimed he did not know that the suitcases contained drugs but thought he was smuggling cash, ultimately destined for the United States. The jury did not believe him.
His mother was also arrested and charged but the investigation did not show that she knew about the drugs. The charges against her were dropped and she was deported.
Kupec challenged both his conviction and sentence in the Court of Appeal and lost. His lawyers did not challenge the minimum non-parole period, however.
He sought leave to appeal his conviction to the Supreme Court and was declined.
He then sought leave to appeal to the Supreme Court against his sentence, arguing his limited knowledge of English meant he did not realise his counsel had not challenged the minimum non-parole period.
“He submits that, if leave [to appeal] is not granted, there will be a substantial miscarriage of justice,” according to a newly-released decision of the country’s most senior court.
Kupec’s application to the Supreme Court was filed out of time, so he sought an extension. The Supreme Court justices turned him down, saying they “do not see any risk here of a substantial miscarriage of justice if leave is not granted”.
Kupec was sentenced in October 2017, meaning he will be able to apply to the Parole Board after April 2026.
The street value of methamphetamine fluctuates but Customs estimated at the time of the seizure that 20kg of the drug was worth $20 million in the New Zealand market.
His sentencing judge concluded that not only did Kupec know he was importing illegal drugs, but he had “cynically” involved his mother to suggest to Customs he was undertaking legitimate overseas travel.