Chris Paine, who was involved in news.com.au's 'Real Heroes Walk Away' campaign discusses what possible impact todays outcome could have in preventing alcohol-fuelled violence in the future.

KIERAN Loveridge has been sentenced to four years jail for the manslaughter of Sydney teenager Thomas Kelly.

Mr Kelly died when he was randomly punched by Loveridge on a night out in Kings Cross.

Loveridge, 19, had pleaded guilty to the manslaughter of Mr Kelly, who was king hit in the notorious Sydney party strip on July 7, 2012.

Mr Kelly's life support was turned off two days later.

Outside the court an emotional Kathy Kelly, Thomas's mother, said she was "horrified" by the outcome.

"[The sentence is] a joke, an absolute joke. And we're horrified," she said.

"This was our son, a boy that was young, honest and starting his life and he's gone. The next person could be your son."

Ms Kelly then called upon lawmakers to toughen their stance on one-punch legislation.

"How many of our children have to die before somebody does something to change these laws, to make people accountable for what they do?" she added.

Absolutely disgusted by this! No justice was done! http://t.co/bsiJ4e2ocH via @newscomauHQ — Michael Dalezios (@Micklez83) November 8, 2013

"Somebody else will be standing here in a couple of months like we are and be heartbroken."

Mr Kelly's father, Ralph Kelly, said the verdict had left his family "cold, shocked and just beyond disbelief".

"Until the state government stands up and says something, and does something instead of avoiding the questions of alcohol-fuelled violence, then these kind of attacks are going to continue again and again and again," he told reporters.

"Our family can't tell you what it's like to lose a child, 18-years-old, who had his whole life in front of him and his life is considered meaningless by the state."

Loveridge was originally charged with murder but the prosecution accepted the lesser plea of manslaughter.

Loveridge was also sentenced for four assaults he committed on the same night that he punched Mr Kelly.

Together with the manslaughter charge, he will spend seven years and two months behind bars with a non-parole period of five years and two months.

How is this justice Sydney? #thomaskelly — Ebony Schmidt (@ebonyswrite) November 8, 2013

The earliest he will be eligible for release is November 18, 2017.

Justice Stephen Campbell said the attacks were random and carried out on strangers.

"One of these attacks has had the most serious consequence," he said.

Mr Kelly's family sobbed as the verdict was handed down this morning, with one family member yelling "oh God no".

In sentencing Loveridge, Justice Campbell said he had since shown "remorse for his offending and for taking the life of Thomas Kelly" and had wept during the reading of victim impact statements by Mr and Mrs Kelly.

He believed Loveridge had shown genuine remorse and took into account the fact the once promising junior league player grew up "without the benefit of love, guidance and support from his father."

A psychologist report described Loveridge as "not the most sophisticated of thinkers" but said he wasn't suffering from "any mental or emotional disorder."

Last month Mr Kelly's parents delivered powerful speeches about their son's legacy as they launched The Thomas Kelly Youth Foundation at a gala event in Sydney.

@newscomauHQ Would he have got longer if he used a firearm ? Seems it's not if you take a life but how you do it. Should have got 10+. — Richard E (@Ebs351) November 8, 2013