Cavanough, of Scarborough, has pleaded not guilty to a charge of manslaughter relating to an incident in which he allegedly punched his second cousin, who he refers to as 'uncle', Allan Neilson, outside the Emerald Chinese Restaurant, Woonona, on the evening of January 25, 2012.

Mr Neilson, who sustained significant facial trauma, was taken from the scene by ambulance officers and rushed to hospital. He died in hospital five months later.

Cavanough was in court on Tuesday, the second day of his trial before Judge Paul Conlon and a 12-person jury.

Interstate witness Kylie Wills, who was dining at the restaurant with a friend on the night of the incident, told the court she was drawn to a commotion on the footpath outside.

"I saw a child on the footpath and she was screaming and she had her hand over her mouth," she said. "I looked forward and there were two men having a fight and it was my instinct to get the children out of the way."

Ms Wills then saw the older of the two men lying on the footpath.

"His face had been hit and blood was coming out of both his nostrils," she said.

Ms Wills didn't see any punches thrown but she told the court of a conversation she had with Cavanough after Mr Neilson was lying on the pavement.

"I asked him who he was and he said: 'He's my uncle. I hit him and I'm going to jail'," she said.

Wollongong general practitioner Dr Michele McGrath, who was driving past at the time, stopped her car along the Princes Highway just after 8pm to provide medical assistance to Mr Neilson.

Dr McGrath said there was significant trauma to Mr Neilson's face, including an obvious fracture in the nasal area.

She said his pulse was within a normal range but she was unable to clear the nasal passages.

The court heard that Mr Neilson's breathing became more shallow and his pulse had dropped by the time an ambulance arrived.

A police officer was asked to drive the ambulance to hospital while two ambulance officers worked on Mr Neilson.

During his opening address on Monday, Crown prosecutor Michael Fox said Cavanough and Mr Neilson had spent the afternoon drinking and playing pokies at the Collegians club before going out to dinner with Mr Neilson's wife and Cavanough's family.

Senior Constable James Sala, the first police officer on the scene, said Cavanough told him he had pushed Mr Neilson after an altercation.

"He's my uncle and I'm Jason," Snr Cst Sala recalled Cavanough said. "He's been hammering me all night in front of my kids ... he took a swing at me. He missed and I pushed him."

The trial will continue on Wednesday with the jury being taken to the footpath outside the restaurant for a site inspection.