Steven Petkovski fronted Wollongong Local Court on Tuesday on nine charges stemming from August 7, 2019, when the officer followed him down a Berkeley street and a scuffle ensued.

But in a bitter blow for the Force, Magistrate Jillian Kiely threw out four charges, including all allegations of assaulting the officer, who departed the scene in an ambulance.

Petkovski, of Unanderra, had just gotten out of jail for possessing a prohibited weapon when Senior Constable Paul Cowan spotted the 36-year-old riding a black and orange trail bike on Winnima Way and followed in his car.

A police radio transcript later captured Sen Con Cowan, by then on foot, breathing heavily as he reported the rider "trying to get away".

Seconds later he added, "I've been assaulted. I'm at Massey and Barnes [streets] ... I need help now ... mate, I'm on top of him ... get a car here now".

Another officer soon arrived and requested an ambulance for the injured senior constable who had "copped a smack in the head ... Conscious and breathing but punched in the head".

In-car camera footage showed the officer confronting Petkovski in a driveway. The camera strangely recedes, the result of the officer having left the handbrake off his car, which the court heard rolled slowly backwards until it came to rest against some garbage bins.

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Meantime, the confrontation continued, with Petkovski back on the bike and Sen Con Cowan giving chase, crash tackling him to the ground.

The court heard Petkovski knocked his head on the road and was briefly unconscious. Both men were afterwards affected by capsicum spray.

Petkovski was charged over a canister of capsicum spray found in his bag, and with refusing an oral fluid test at the scene.

Sen Con Cowan told the court he had been involved in multiple police pursuits during his career and was trying to stop one from occuring when he acted. He said he hadn't had time to pull off a by-the-book arrest, a claim contested by defence barrister Ben Hart.

"He had 42 seconds [since the pursuit began] to decide what he was going to do when he got out of the car," Mr Hart said.

"He made the decision without introducing himself, without asking for ID or taking steps other than demanding that Mr Petkovski get on the ground and taking hold of him."

Police checks later revealed the bike had been stolen from Corrimal Beach Tourist Park in May.

Magistrate Kiely found the officer had failed "to even remotely comply" with section 202 of the Law Enforcement (Powers and Responsibilities) Act 2002, which sets out the information police are supposed to provide when exercising their powers.

"Words that were spoken initially upon approach, the actions that he took subsequently, the struggle, the tackling, the pepper spraying, the drawing of the weapon - I think all of these things combined would have lead to a real doubt as to the legality of the ... prosecution of those charges," she said.

Petkovski spent almost four months remanded in custody before he was granted bail, then another seven months effectively under house arrest.

Charges of assault occasioning actual bodily harm, take and drive, resist arrest and assaulting an officer were thrown out on Tuesday.

But Petkovski was convicted of driving disqualified, using a prohibited weapon contrary to a prohibition order, possessing a prohibited weapon, driving without number plates and refusing an oral fluid test.

Mr Hart made a bid for almost $25,000 in legal costs.

But police prosecutor Leah Argent whittled the sum down to $6124.94, successfully arguing Petkovski had been found guilty of five offences, and that it was not for the Force to pay for his decision to enlist two barristers.

"We should not be paying the costs of the accused person's bail application to a sum of $8500 in circumstances in which, regardless of the charges that were dismissed today, there would have been the same course of action, so I ask for that sum to be removed from the total," Sgt Argent said.

The magistrate agreed with prosecution submissions that Petkovski was not likely to have been granted bail regardless of the now-dismissed charges, given his lengthy criminal history, which included convictions and jail terms for malicious wounding, robbery with intent, steal motor vehicle, traffic offences, reckless driving and threatening witnesses.

The magistrate accepted Petkovski had made "significant steps to turn his life around" since he married six years ago.

With time already served, he was fined a total of $1760, disqualified from driving for three months and placed on a six-month intensive corrections order. He was also placed on a year-long community corrections order.

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