Sydney psychiatrists Dr Olav Nielssen and Dr Richard Furst on Friday agreed Oliver Tam Scales-Copeland's cocaine use exacerbated his schizophrenia before he attacked the officers last year, but he had been mentally ill for several years.

The psychiatrists told Newcastle District Court that Scales-Copeland was aware of what he was doing when stabbing the officers, but did not know it was wrong.

Scales-Copeland claimed he stayed awake all night after taking cocaine before driving from Sydney to Lake Macquarie on Sunday, October 6 and attacking the two senior constables about 1pm outside a Toronto service station.

He admits stabbing the officers but denies being criminally liable, claiming he did not know what he did was wrong because of his mental illness.

Dr Furst said Scales-Copeland had "acute psychotic symptoms" at the time of the stabbing and remained psychotic for several months after his arrest.

Scales-Copeland, from Bronte in Sydney's east, has pleaded not guilty due to mental illness to two counts of wounding with intent to prevent arrest.

He also faces two alternative counts of reckless wounding, one count of using an offensive weapon to intimidate and an alternative count of assault.

The 26-year-old is the son of Greens councillor George Copeland on Sydney's Waverley Council.

Dr Furst told the court Scales-Copeland was having paranoid delusions, believing his life was in danger when he stabbed the officers.

Dr Nielssen said Scales-Copeland's "grossly disordered thinking" meant he did not realise what he was doing was wrong.

He was wearing only red underpants when he began threatening motorists with a knife before the two police officers approached him at the Caltex service station.

When ordered to drop the knife, Scales-Copeland called out "come on dogs, I'll take you on".

The officers used capsicum spray and a baton to try to disarm Scales-Copeland and were wrestling with him when he stabbed one officer five times in the left thigh and the other officer once in the right hand, cutting one finger to the bone.

Both officers opened fire on Scales-Copeland but missed before he was arrested with the help of bystanders.

When later questioned by police, he claimed to have no memory of stabbing the officers.

Prosecutor Kristy Mulley said there was no dispute about what Scales-Copeland had done but he claimed he was mentally ill at the time.

The judge-alone trial before Judge Tim Gartelmann continues.

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