The two officers now face serious charges, including attempting to pervert the course of justice, and abuse of public office.

The incident took place in the early hours of April 2, 2016.

The off-duty AFP officer, Wade Howell, 35, was in Canberra from Melbourne for training and was out drinking with friends the night of the alleged incident.

The alleged victim, 45, and his partner, 42, were also out in Civic that night.

Both groups had ended up at Mooseheads.

About 2.30am, the woman left the bar and headed in the direction of her hotel Medina. CCTV allegedly shows the officer follow the woman about 10 seconds later.

She sat on a bench, and it's alleged Mr Howell joined her. She later told police she was scared of his intentions.

She hoped her partner would see her on his walk home.

A few minutes later, he found them on the bench at Veterans Park.

Mr Howell said the boyfriend "aggressively" approached them, so he shoved the man in the chest, forcing him backwards.

The woman warned her boyfriend: "Don't hit him, he's a cop."

When the man tried to walk towards his girlfriend, the officer punched him in the nose, and in the head and face four or five more times.

The alleged victim does not remember hitting the ground, but told police that, while there, the officer straddled and choked him. The officer allegedly continued to punch the man's face.

At some point, feeling nauseous, the girlfriend fled to their hotel.

The officer eventually got up off the ground then helped the man to his feet, apologised to him and said: "You're a lousy fighter."

It's said the man could not speak for the blood in his mouth. Scared to leave, he hung around before heading back to the hotel.

It's alleged the officer followed him back to the couple's room.

Once there, the officer allegedly spoke to the man's girlfriend about domestic violence, and said he would protect her. She later said the officer seemed "really drunk", and she just wanted him to leave.

The woman tried to go in the room with her boyfriend but the officer stopped her. Her boyfriend said she needed to listen to the officer.

About 3.20am, Mr Howell called police communications for assistance.

ACT Policing Acting Sergeant Andrew Smith, 45, was the first to arrive. He said he recognised Mr Howell as he used to work in Canberra.

The sergeant took the victim into protective custody for being drunk and disorderly. A constable protested and said they needed to investigate the assault, but the sergeant said he was going in.

At the watch-house, Mr Smith said an officer had assaulted the man in self-defence, and his girlfriend did not want him back that night.

The constable said: "This is f---ed ... This bloke was bashed by a cop and we're locking him up," before walking off, the documents say.

The man spent an hour in the cells before he was taken to hospital.

It's alleged the sergeant lied on the police statement of facts. He wrote that a sobering-up shelter had no space available at the time, but the shelter manager later told police it did have a bed, and she had no record of any call about the man that night.

The sergeant wrote that the alleged victim was moderately affected by alcohol, and smelled heavily of drink. He wrote that the man's eyes were bloodshot, and he was unsteady on his feet.

But other police officers who were at the hotel and the watch-house have contradicted that assessment, describing the alleged victim as coherent, polite, compliant and not smelling of alcohol.

Mr Smith appeared in the ACT Magistrates Court on Friday charged with unlawful confinement, abuse of public office, giving false or misleading information, and attempt to pervert the course of justice.

Mr Howell is charged with assault, recklessly inflict grievous bodily harm, choke, and attempt to pervert the course of justice.

In two separate appearances on Friday, Magistrate Bernadette Boss committed both men to stand trial in the ACT Supreme Court.

Neither officer has entered any pleas. Both are out on bail. The matters are next due in court on May 4.