The High Court has averted what would have been a catastrophic situation for the ACT legal system, dismissing an appeal that threatened to invalidate decades of convictions.
Its decision on Tuesday will be a relief for ACT Attorney-General Shane Rattenbury, whose lawyers had warned a successful appeal would have "extensive consequences" for the administration of justice.
The case involved Canberra gang rape leader Saimoni Vunilagi, aged in his mid-30s, challenging the constitutional validity of a judge-alone trial that ended with him being found guilty of eight charges.
The Fijian, also known as Simon Vunilagi, was described as the "ringleader" of a group that raped a young woman in Downer after meeting her at Civic nightclub Mooseheads in 2019.
Vunilagi wanted to be tried by his peers but the ACT Supreme Court placed his fate in the hands of a judge in 2020, when the Legislative Assembly had passed emergency laws suspending jury trials.
He later tried unsuccessfully to convince the ACT Court of Appeal his trial had been incompatible with the constitution, which requires juries for offences against Commonwealth law.
The High Court subsequently gave him another chance to make that argument, conducting a two-day hearing in February.
Barrister Bret Walker SC accepted Vunilagi had been charged under ACT laws but argued these derived their force from Commonwealth legislation, meaning the constitution prohibited a judge-alone trial.
But ACT Solicitor-General Peter Garrisson SC, appearing for Mr Rattenbury, argued the territory's laws were not made under the authority of the Commonwealth Parliament and a judge-alone trial was therefore permissible.
He warned Vunilagi's appeal being upheld would overturn "decades of practice" in the ACT, rendering the 30-year regime of optional judge-alone trials unconstitutional.
Mr Garrisson said "countless" convictions had been obtained in such cases since 1993.
Commonwealth Solicitor-General Stephen Donaghue KC, who also urged the High Court to dismiss Vunilagi's appeal, described the potential impacts of its success as "quite startling".
"Any convictions in such trials would be invalidated," Dr Donaghue told the court in February.
Dr Donaghue said the issue would also have an impact on the Northern Territory, which had, like the ACT, "long permitted" judge-alone trials.
The High Court held on Tuesday that Vunilagi was not charged under Commonwealth law.
"Therefore, [Vunilagi] did not need to be tried by jury," the court found.
With Vunilagi's appeal accordingly dismissed, his jail sentence of more than six years stands.
He became eligible for parole in June but remains behind bars.
Former ACT chief justice Helen Murrell, who sentenced Vunilagi following his trial in 2020, said back then the Fijian was almost certain to be deported upon his release from prison.
