The High Court has delayed the murder trial of NT police officer Zachary Rolfe.

Thirty-year-old Constable Rolfe is charged with the alleged shooting murder of Yuendumu man Kumanjayi Walker in 2019.

Less than an hour before the trial was due to commence last week, High Court Justice Jacqueline Gleeson ruled that the case was of an exceptional nature and would be stayed until a special leave application in September.

It is the latest delay in a trial that had already been pushed back by COVID-19 lockdowns in Sydney, which affected the Sydney-based prosecution team, and in Darwin, which prevented court operations too. 

The case will return to the High Court for a special leave application on September 10, which could mean the trial does not begin until 2022. 

Justice Gleeson said the nature of the case, involving the alleged murder of a young Aboriginal man by a serving police officer, means it would be an injustice if there was an acquittal on the basis of a wrong legal construction.

“The trial of a member of the police force, whose functions included the protection of life, in connection with the death of the deceased, is a matter of the gravest community concern,” Justice Gleeson said.

Nineteen-year-old Kumanjayi Walker died after being shot three times by Constable Rolfe as four officers attempted to arrest him in the remote Aboriginal community of Yuendumu in 2019.

At a committal hearing last year, expert criminologist Dr Geoffrey Alpert gave evidence based on police body-worn camera footage from the shooting, saying he believed the first shot Constable Rolfe fired during a struggle with Mr Walker was “reasonable” but two follow-up shots were “excessive, unreasonable and unnecessary”.

Four officers had attended a home in Yuendumu to arrest Mr Walker, who allegedly hid his face under a hat and gave a false name, before trying to back away with a pair of scissors in his hand, the committal hearing was told.

In a resulting struggle, Mr Walker allegedly stabbed Constable Rolfe, who then shot him, the court heard. The second and third shots came after Walker had been restrained, Dr Alpert said.

Constable Rolfe is also facing alternative charges of reckless or negligent conduct causing death, or engaging in a violent act causing death.

Earlier this month, the NT Supreme Court ruled that Constable Rolfe could argue three separate defences.

One possible defence is that he should not be held criminally liable if a jury finds he acted in “good faith” as a police officer during the arrest of Mr Walker.

Prosecutors say that if Constable Rolfe can use a “good faith” defence he may be able to avoid criminal liability and any consideration of whether his action was reasonable in the circumstances.

A hearing has been held in the NT Supreme Court to formally dismiss the jury pool and discuss future dates for the case.

There is some suggestion that new trial dates may be found in November or December this year.