Police officers appeal Australia Day assault conviction

Senior Constable Matthew McVicar, 36, and Constable James Head, 30, were at the tail end of a long Australia Day shift in 2017 when they pulled over a teenager for driving through the Civic bus interchange, where cars are prohibited.

The driver had said that, because there was a taxi rank upon turning left onto London Circuit, he did not immediately pull over, but waved to the police car that he was heading for the Mooseheads car park across the road.

Once he had pulled into the car park, the two officers approached the car. At one point the front seat passenger began filming from her seat and captured the moment Head says he would search the back seat passenger for "being a smartarse" before swearing at him to "get the f--k out of the car".

The video shows a scuffle and the court heard one officer had the 19-year-old in a headlock and the other had his arm as they pulled him roughly from the car. The officers are heard to say on the video that they've arrested the man for resisting arrest, and later told the court the man had tried to stay in the car by moving his legs.

The two officers were charged with assault occasioning actual bodily harm following an internal investigation and pleaded not guilty, arguing they were acting in the execution of their duties.

During the hearing in the ACT Magistrates Court last year, the officers argued there had been an earlier interaction before the one that was filmed in which they had repeatedly warned the teenager they would arrest him for hindering police.

They said they were drawn away from the car to arrest another man who they had already given a move on direction but who they had seen sitting on a brick wall in the car park.

But Magistrate Robert Cook found the pair guilty of a lesser charge of common assault, saying the force used was highly excessive and that they had no legal justification.

On Wednesday in the ACT Supreme Court, lawyers for McVicar and Head appealed the conviction arguing a miscarriage of justice.

The court heard that evidence from an independent witness, to the late-night incident that had not previously been disclosed to the defence. The witness gave evidence at the appeal, saying of the incident that "they were sort of like a good cop and a bad cop".

But she appeared to struggle to remember details of the night from more than two years ago.

Barrister James Sabharwal said there was new evidence before the court, that the magistrate had failed to take into account the police officers' earlier direction and a lack of procedural fairness in that the finding of excessive use of force had not been put to the parties.

Mr Sabharwal said the first interaction went to what was in the minds of the officers when they went to arrest the teenager for hindering police.

He said the magistrate had relied heavily and disproportionately on the video, which showed the second interaction.

Prosecutor Trent Hickey said the new evidence did not change the result of the charges.

He said on the existing evidence it was implausible that the officers warned the group five or six times that they were going to arrest one of them, and then go to arrest another person without warning those in the car to stay put.

He said in the second interaction, the one filmed, there was no reference to the alleged earlier warnings about an arrest for hinder and instead among the first words from the officer to the back seat passenger was a question about his age.

The officers did not have a reasonable belief there was a hinder and the passenger's actions did not give rise to a lawful arrest, the prosecutor said.

He said there was no miscarriage of justice in the case and no lost chance of acquittal.

The judge can either uphold the appeal and remit the case for another trial in the magistrates court or dismiss the appeal.

Justice David Mossop reserved his decision.