Thomas Kelly law petition reaches 100,000

More than 100,000 people have signed a petition started by the parents of single-punch victim Thomas Kelly, calling for tougher sentencing laws for alcohol-related violence.

With 104,687 signatures as of 3.55pm (AEDT) on Monday, the petition is the fourth most popular on social change website, change.org.

At 3.20pm, the petition was at 100,020.

Thomas Kelly, 18, died after being hit with a single punch at Sydney's Kings Cross entertainment precinct in July 2012.

His parents, Ralph and Kathy Kelly, are calling for drunkenness to be a mandatory aggravating factor that must be taken into account in sentencing.

"To get 100,00 signatures on our change.org petition shows the depth of feeling in the community about the issue of alcohol-fuelled violence," Mr Kelly said in a statement.

"Kathy and I are incredibly grateful for the support we've received, and we hope it demonstrates to the state government the need for action."

The petition, started in November, was at about 25,000 signatures before New Year's Eve.

On that night, 18-year-old Daniel Christie was allegedly punched just metres from where Thomas Kelly was attacked in Kings Cross. He remains in a coma in a critical condition in St Vincent's Hospital.

Change.org communications director Tony Robertson said the spike in numbers has happened in the six days since Mr Christie was bashed.

"All that growth has been since then," Mr Robertson told AAP.

The petition also calls for alcohol to be taken into account if the attacker is on a good behaviour bond and for victims' age and inability to defend themselves to also be taken into account in sentencing.

Mr Robertson said the Kellys' petition was now the fourth most popular in change.org's history in Australia (Australian signatures only).

"It's likely the Kellys' petition will soon become the second largest that change.org has hosted in Australia in terms of local signatures," he said.