Constable Zachary Rolfe, 29, shot Kumanjayi Walker, 19, in the remote community of Yuendumu in November 2019.

Rolfe fired his gun from close range after Mr Walker stabbed him with a pair of surgical scissors as he and a fellow officer struggled to handcuff him.

The Territory's top court on Wednesday heard legal arguments related to Rolfe's case and the NT Police Administration Act.

Defence lawyer David Edwardson QCs says the legislation contains provisions that give police officers immunity in certain circumstances if they were performing an authorised duty in "good faith" at the time.

"This provision can provide defence for the accused in respect to all three charges he faces," he told five judges on the full bench of the NT Supreme Court.

"It is common ground that section 148B in the form of a defence provides immunity from liability, not from prosecution."

Rolfe is charged with murder and the alternative charges of reckless or negligent conduct causing death, and engaging in a violent act causing death.

His trial was postponed last week due to COVID-19 after the Crown's NSW-based prosecution team found themselves unable to travel to the Top End.

Trial judge Acting-Justice Dean Mildren referred four questions to the court to consider so he could better understand the Act.

The answers are likely to determine what Justice Mildren instructs the jury to consider when Rolfe's trial goes ahead.

Mr Edwardson told the court Rolfe has three defences available to him.

They are the "good faith" clause of the NT Police Administration Act; that Rolfe was performing his duty as a police officer when the shooting happened; and that he was acting in self-defence.

But prosecutor Philip Strickland SC said Rolfe wasn't performing a duty in "good faith" outlined in the Act and isn't afforded its protection.

Mr Edwardson said Rolfe was protecting himself from Mr Walker, who was armed with scissors and threatening his partner.

But Mr Strickland said the Act didn't give individual officers the power to prevent crime and its protections were not relevant to Rolfe if that was his intent.

The legislation empowers the police force to perform that role and the commissioner issued general orders on officers to carry out the function, he said.

The court reserved its judgment.

Australian Associated Press