The first person charged under NSW's one-punch law has been sentenced to the mandatory minimum eight-year jail term for killing a Sydney nurse outside a 21st birthday party in 2014.
Hugh Bacalla Garth was found guilty in May of assault causing death while intoxicated after he delivered one punch to the head of Raynor Manalad, 21, outside the Rooty Hill party.
Mr Manalad "tragically never regained consciousness", Judge Antony Townsend told the NSW District Court on Friday as he set a maximum term of 10 years.
"It is now notorious that a single punch can not only cause catastrophic injuries but also death."
The one-punch legislation was introduced in 2014 after the deaths of Sydney teenagers Daniel Christie and Thomas Kelly.
It sets a mandatory non-parole period of eight years and a maximum of 25 years if the offender is under the influence of alcohol or drugs. No mandatory minimum term applies if the offender is sober at the time of the attack.
Garth's barrister had unsuccessfully argued the mandatory minimum eight-year term was constitutionally invalid because it was a case of the parliament restricting the judiciary.
Outside court, the victim's mother, Teresita Manalad, who lost her only child, said the sentence didn't matter as she'd "accepted Ray's passing from the very beginning".
"I don't feel anything for him (Garth) and the family," she said.
"I won't waste any breath, any part of my brain for them."
Garth had been at the 21st birthday party of Myrik Ong, who at one stage told him "to respect the family home" and to look after his 'little cousin" who was Garth's girlfriend.
But when outside, Garth pushed Mr Ong with both hands, resulting in him falling and fracturing his ankle.
Mr Manalad then asked Garth why he did it, holding onto Garth's shirt in a way witnesses described as a bid to calm him down.
But Garth used a closed fist punch to strike Mr Manalad on the side of his face, causing him to fall to the ground. He never regained consciousness.
The judge found the objective seriousness of Garth's crime to be "well below the mid-range", also noting the need to deter others being violent after drinking to excess.
But he said the offending could not be seen as "an aberration", noting Garth was on a good behaviour bond for assault and breaking a domestic violence order at the time.
One-punch attacks committed after excessive drinking understandably caused "grave disquiet", anger and frustration in the community, he said.
In her victim impact statement, Ms Manalad told the court her son would have turned 25 in October and had planned to become a psychiatrist to help those with addictions to alcohol and other drugs.
"Isn't it ironic about how he died and how he was killed," she said.