A judge has released video showing a portion of an arrest involving Calgary police officers delivering what the prosecution has called "tremendous violence" to an unarmed suspect who was lying on the ground.

The video shows about six seconds of the arrest during which officers, identified as James Othen and Kevin Humfrey, deliver several blows to Prince after he had surrendered, with his hands behind his head.

Othen, Humfrey and another officer, Michael Sandalack, are on trial, charged with assault causing bodily harm in relation to the arrest.

Their alleged victim, Clayton Prince, suffered broken ribs and a collapsed lung during the arrest in July 2016.

Calgary police officers James Othen, left, Michael Sandalack and Kevin Humfrey attend Calgary court for their trial. (Meghan Grant/CBC)

On Tuesday, after the Crown was finished questioning its second witness, Const. Chris Harris, defence lawyers had their turn questioning the officer, who had earlier described the arrest as "violent" and "out of control."

Under prosecutor Jim Stewart's questions, Harris — whose drawn service gun caused Prince to drop to the ground with his hands behind his head — said he wanted no part of the arrest.

What could have been a two to three second arrest turned into two to three minutes of violence, according to Harris.

"He could have been handcuffed immediately," said the five-year officer.

One of the responding officers, who is not on trial, turned off the cruiser's emergency lights, which caused the recording to stop, but Harris testified officers continued to attack Prince after the video stopped rolling.

'We got the bad guy, hooray'

Harris said he only made detailed notes when he found out how serious Prince's injuries were and after hearing from a sergeant about how to protect himself.

"It's a very difficult position to be put into," Harris testified.

He also said the officers' attitudes after the arrest was "jovial, like, 'we got the bad guy, hooray.'"

After learning Prince had suffered serious injuries, Harris said "my primary purpose in writing notes was self-protection."

Photos show some of the injuries Clayton Prince sustained when he was arrested by Calgary police officers who are now on trial. (Clayton Prince)

Harris said he kept his notes but didn't turn them in because he worried they would have "negative consequences" for his fellow officers. It was after he was contacted by the Alberta Serious Incident Response Team (ASIRT) that he gave a full statement.

Under cross-examination, Harris confirmed he and the other officers couldn't say for sure whether Prince was armed and that their adrenaline would have been flowing.

"Perception is not perfect and memory is not perfect," Humfrey's lawyer David Butcher suggested to Harris. "Most people who run from police have a reason to do so."

Butcher also got Harris to admit that the one blow Humfrey can be seen delivering on the video was not necessarily excessive.

"I am not a use-of-force expert … but I would say that one punch could potentially be an acceptable level of use of force," said Harris.

Pursuing charges

Cst. Derrick Matkar, the last witness to testify on Tuesday, was the one who pulled Prince's car over on July 30, 2016 after noticing the suspect's dirty license plate.

Matkar said he didn't see the takedown, but afterwards Othen, Humfrey and Sandalack told him a version of the arrest that contradicted the video, which surfaced later.

They said when Prince was told to get on the ground, he refused so officers tackled him. Then they said he refused to show them his hands.

That, plus their later written statements, led Matkar to pursue charges and an investigation into allegations of resisting arrest.

Othen also faces charges of mischief and assault with a weapon for allegedly digging the key into Prince's neck, while Humfrey is also charged with two counts of public mischief in relation to false statements the two officers are alleged to have given after the incident.

Prince ran from police

Prince, a resident of High Level, Alta., had been in Calgary for the Chasing Summer music festival with his girlfriend on July 30, 2016, when police pulled him over for a traffic stop in a parking lot in the 6700 block of Macleod Trail.

Instead of complying with the first officer's demands to stay in the car, Prince says he took off because he was paranoid after taking cocaine and marijuana and had been driving without a licence.

After running through a sushi restaurant, Prince said he tried to hide in some trees but was flushed out by more officers who arrived on scene. When one officer pulled a gun, Prince got down on the ground and put his hands on his head.

Prince suffered a collapsed lung and broken ribs during the arrest. Afterwards, he said he was thrown into a police car, which split his lip, and then was punched behind the ear by an officer holding a key in his fist.

2 officers suspended without pay

Eventually, the video from a police dashcam surfaced, contradicting the officers' accounts of the incident, prompting an investigation led by ASIRT.

Defence lawyers Alain Hepner, Paul Brunnen and David Butcher represent the officers.

Othen and Humphrey are suspended without pay while Sandalack is on administrative duties.

The trial is set to last all week.