Fulton denies the charge and says the assault was justified.
Yesterday the jury was shown CCTV footage of the confrontation that night.
In the video, Watson is seen throwing a bottle and Fulton reacts by jolting away.
Fulton then grabs Watson in a restrictive hold from behind.
Less than a minute later Fulton pushed on Watson’s chest with both hands, causing him to fall backwards on to the concrete where he lay motionless.
Lawyer Hugo Young outlined the defence, saying Watson was “disorderly and out of control” on the night.
The defence says Fulton was, in the circumstance of this particular case, legally justified in pushing Watson away from him as he did.
“Either Mr Fulton was acting in defence ... and/or he was preventing a breach of the peace.”
If the jury agreed that was the case, Fulton must be found not guilty, Young said.
Crown prosecutor Mary-Jane Thomas said given the circumstances, Fulton should have known the assault was likely to cause more than trivial harm.
The court heard from the Newfield Tavern courtesy coach driver, who knew both men as regulars at the pub.
She said they were arguing because Watson was trying to bring his bottle into the van, and that was against the rules.
The driver said Watson just wanted to get into the coach, and after Fulton told him not to bring his drink on board, he threw the bottle across the carpark.
“I was actually quite surprised he threw it – no one’s ever done that.”
She was panicked about the escalating nature of the argument.
“I could see that it wasn’t going to resolve itself.”
The driver was shocked by the incident and was surprised the pair were so angry over getting into the bus.
“Kevin’s normally [a] happy-go-lucky, calm farmer.”
She recalled Fulton saying things such as “why the f*** would they let you in if you’re biffing stubbies?” and “get the f*** out of my face” before the fatal push was delivered.
She had saved enough seats on the coach for Fulton, his friend and Watson.
She did not leave the tavern until the ambulance had taken the victim, who was conscious and talking at that stage.
Later, she dropped Fulton home in the coach.
The assistant manager was called to help when the men were becoming worryingly agitated.
He came out and saw Watson being pushed to the ground.
There was a loud “crack” as his head hit the concrete, the driver said.
“I remember him falling like a tree.”
After the push, she grabbed Fulton by the arm to prevent any further trouble.
Another regular who was in the passenger seat of the van during the fight spoke to Fulton shortly after the assault.
He recalled the defendant saying “I barely touched him”.
Fulton was “distraught” and not his usual self, he said.
The trial is being presided over by Justice Jonathan Eaton and is expected to take a week.
