Matthew Domio, 31, was highly intoxicated when he punched his father, Dario, during an argument in their home in Dapto, in Wollongong's south, in May last year.

Dario Domio, 53, was rushed to hospital unconscious and with bleeding on his brain. He died two days later.

In an interview with police in the hours following the attack, Matthew Domio said, "He was in my face. I just snapped."

The state government introduced a mandatory minimum sentence of eight years' jail for offenders who carry out an assault that causes death while intoxicated.

The controversial legislation was sparked by the deaths of teenagers Thomas Kelly and Daniel Christie in Kings Cross by drunken strangers.

In the NSW Supreme Court on Thursday, Mr Domio's barrister Robert Webb said his client might have a case of self-defence. He said the onus fell on the prosecution to negate self-defence.

Mr Webb said Dario Domio had been involuntarily scheduled in Shellharbour Hospital for seven days 2½ months before his death due to a proclivity for drunken violence, particularly against his son.

Mr Webb said that, on the night of the incident, both father and son were drunk.

He said there was a long-time dysfunctional and violent relationship between the pair and, in the past Matthew Domio had tried to protect his mother from domestic violence carried out by his father.

Mr Webb said there had not been many cases under the mandatory sentencing legislation but it could be possible that Matthew Domio faced a much lesser sentence than eight years, and might not face jail time at all.

The Crown prosecutor said Mr Domio had an alcohol problem and a history of assaulting police when drunk. At the time of the incident he was on a good behaviour bond for assaulting a police officer six weeks earlier.

He said there was no evidence Mr Domio felt scared of his father in the immediate lead-up to the fatal assault.

He said that, after the punch, Mr Domio sought help from his brother, who moved their father into an armchair.

His father complained about having lost a tooth and spoke to his former partner on the phone, before eventually losing consciousness, the facts said.

Realising his father had become unresponsive, Mr Domio and his brother raised the alarm.

Justice Christine Adamson granted Mr Domio bail on the condition he abstain from alcohol and drugs and report daily to police.

More than a dozen of Mr Domio's family and friends attended the bail hearing. A crowd funding appeal has raised more than $20,000 towards his legal fees.

In appealing for donations, the fundraising organiser, Alana Heffernan, who is Mr Domio's sister-in-law, wrote: "This is not a crime but a family tragedy!

"A family torn apart by a split second decision that could have happened to anyone. A father has lost his life and a brother/son taken into custody," she wrote on Oz Crowd.

"This a family made up of four boys, the best of mates and a family that values each other above anything else in this world and would do anything for one another at the drop of a hat.

"They have not only been dealt the hardest blow by losing their father but cannot begin to deal with their grief as their beloved older brother is behind bars looking at a large part of his life taken away from him.

"Some might judge this family before even putting yourselves in their shoes, so please before you do think about how this could happen to your family and please say a little prayer for them and send them well wishes," Ms Heffernan wrote.

Mr Domio will face trial in August.