A police officer who ran over a young motorcyclist during a traffic stop in Adelaide's north has been found guilty of aggravated driving without due care.

Key points: Police officer Matthew Lumsden ran over a motorcyclist in May 2017

Police officer Matthew Lumsden ran over a motorcyclist in May 2017 He claimed he was not driving because he was not in control of the vehicle

He claimed he was not driving because he was not in control of the vehicle The magistrate rejected his argument

He was placed on a 12-month good behaviour bond and disqualified from driving for six months.

Senior Constable Matthew Lumsden, of the Road Policing Section, stood trial in the Elizabeth Magistrates Court earlier this year.

The court heard Lumsden was responding to a report of street racing when he came across two riders in McCarthy Court at Parafield Gardens in May 2017.

Magistrate Sue O'Connor found Lumsden failed to put his police car in park and when it rolled forward, he hit the accelerator instead of the brake to stop the vehicle, running over Benjamin Wormwell, 17.

"The police car rolled over Mr Wormwell and his bike at sufficient speed to allow its momentum to continue after the collision, and the car mounted the kerb and rolled onto the footpath," Magistrate O'Connor said.

Lumsden's lawyer told the court his client was genuinely remorseful. ( ABC News )

"As an experienced police officer with vast experience with such traffic offences, his failure to engage park suggests panic or a lack of care due to rushing to detain motorbike riders he assumed had committed an offence."

Magistrate O'Connor rejected Lumsden's argument at trial that the incident did not amount to an act of driving because there was no element of control.

"He was in control of the police car when he started to leave it without putting the gear shifter in park," she said.

"He was in control of the vehicle when he tried to depress the footbrake but hit the accelerator.

"I reject that his actions were involuntary, and I reject that his mistakes or misjudgements should be seen as accidental and not careless."

Victim doubts if officer remorseful

Lumsden's defence lawyer told the court his client was genuinely remorseful and the accident had a "sobering and dramatic effect" on him.

But outside court, Mr Wormwell said he did not believe Lumsden was contrite.

"He has had many chances to say sorry to me — even today he didn't say sorry," he said.

Benjamin Wormwell said he had suffered serious pelvic and leg injuries. ( ABC News )

"I don't think he is remorseful at all."

He welcomed the magistrate's decision to record a conviction.

"I missed out on the rest of my schooling, my education and jobs and … now because I'm a liability, it's a lot harder than it was before the accident," he said.

"Obviously the six months and fines aren't going to reflect what I went through, but at least he didn't get off scot-free."

In handing down the sentence, Magistrate O'Connor said a six-month loss of licence would have a "marked impact" on Lumsden's policing career.

"Up and until now you have been hardworking, diligent and respected and have had a good police career, which has now been marred by what seems to have been a temporary misjudgement of a circumstance," she said.

"You have made a very bad misjudgement of the situation but it's not suggested that that's in your character."

Car 'went over me, spat the bike out'

Mr Wormwell suffered multiple broken bones and had screws inserted in his pelvis, as well as a rod in his femur.

He had to spend 10 weeks in hospital.

The apprentice mechanic previously told the court he had been visiting a friend when the incident occurred.

He said the police car "went over me, spat the bike out and dragged me between the footpath and the kerb".

"It was an aggressive acceleration — it was quite fast and the engine revved quite a lot," he said.

"I instantly put my hands up and proceeded to say, 'I'm sorry, I don't know what I've done'.

Lumsden told the court he believed Mr Wormwell was trying to "possibly evade" him.

"The rider's hands came up briefly and his hands came off the handlebars," he said.

Lumsden said he tried to use his left foot to stop the car rolling but instead hit the accelerator.

"It forced my body back into the car and at that point, I had no control of the car," he said.

"Despite all of the efforts we made, there was a momentary distraction in putting the vehicle into park."