But lawyers for the two Canberra officers said they were acting in their execution of their duties when they arrested the teenager that night, and were just doing their job.

Senior Constable Matthew McVicar, 35, and Constable James Head, 29, were charged with assault occasioning actual bodily harm following the late night Australia Day altercation. They pleaded not guilty.

The ACT Magistrates Court heard this week at a hearing over the charges that the two officers had pulled the driver over after seeing him travel into the Civic bus interchange - where cars are prohibited - late on Australia Day last year.

A dramatic video tendered to court and played at the hearing captured the altercation between police and the passenger. The footage - which the court has declined to release - shows Constable Head threatening to search the alleged victim for being a "smart arse" before swearing at him to get the "f--k" out of the car.

Amid further swearing, including one officer telling the teenager to "give me your f---king hands c--t", the two officers bundle him out, put him face down on the ground and cuff his hands behind his back.

But there was a first encounter with the group in the car only moments earlier that was not filmed, and what is said to have happened during that encounter is heavily disputed.

Prosecutors allege that Senior Constable McVicar had a brief conversation with only the driver once he was pulled over. The defence has disputed this account however, alleging that during the encounter the back seat passenger was "belligerent" and "argumentative", repeatedly interrupting the officer trying to speak to the driver. Senior Constable McVicar said he warned the teenager multiple times that if he continued to interrupt, he would be arrested for hindering police.

While Senior Constable McVicar was speaking to the driver, a pedestrian walked past who caught the attention of both officers, and they left the car briefly before they returned, and the alleged assault occurred.

Prosecutor Dean Sahu Khan told the court in his closing arguments that the officers had "no right, power or authority to manhandle" the teenager as they did".

He said if the court found there was no authority for the arrest, it would have no difficulty finding the charge proved.

"If there was no effective arrest, or sufficient basis for arrest, then what the defendants did amounted to assault," he said.

He said that the teenager had interrupted the officer just once before he was purportedly arrested for hindering police.

Constable Head did not tell the alleged victim why he was being arrested, as was required, Mr Sahu Khan said.

That the officer had said he was "anxious" when they pulled the car over explained his behaviour but did not excuse it, the prosecutor said.

But Senior Constable McVicar's barrister James Sabharwal said the circumstances around the traffic stop were important. He said the officer was acting in the execution of his duty when he pulled the teenager over.

He said the court would have no trouble accepting that the alleged victim was drunk that night, and pointed to the evidence of another witness who said the teenager became "unreasonable" when he had been drinking.

He also said the alleged victims injuries - of scraped elbows and arms - was not consistent with actual bodily harm. He said that although the teenager had complained of nerve damage to his thumb, there was no objective evidence of that injury.

Constable Head's lawyer Tim Sharman told the court that the witnesses from inside the car had given various accounts of what happened that night.

He said the officer's anxiety before the traffic stop explained the language he used and the "jumbled" way he expressed himself. He said it did not matter that the words of the arrest were not expressed precisely, because the teenager knew why he was being arrested.

"He was doing his job," Mr Sharman told the court, "and they are not guilty."

Magistrate Robert Cook will deliver his decision at a later date.