The Solicitor-General is looking into the case of Wellington Lions rugby player Losi Filipo following an outcry over him being discharged without conviction.
The attack happened in central Wellington in the early hours of a Saturday night in October 2015.
Mr Filipo avoided a conviction after high-ranking rugby officials wrote letters to the courts on his behalf, including agent Warren Alcock, Wellington Rugby CEO Steve Rogers and Petone Rugby Football Club's Darren Larson.
He was also backed by Upper Hutt Mayor Wayne Guppy.
Mr Filipo's brother also faced one charge of assault with intent to injure relating to one of the victims and was convicted, fined and sentenced to supervision. He had prior convictions.
While Prime Minister John Key wouldn't comment specifically on the case, he said violence is "unacceptable anywhere".
"It doesn't matter what your profession is. If you undertake violence you should be held to the same set of rules as everyone else."
When asked if a Crown appeal was possible, Mr Key said that was a decision for the Solicitor-General.
Crown Law says it didn't know about Mr Filipo's case until the story appeared on Newshub on Monday.
In a response to a letter from Family First, in which they ask for an appeal of Judge Bruce Davidson's sentence, Crown Law says it is now "looking into this matter".
It would not comment further.
The letter, signed by national director Bob McCoskrie, calls the outcome of the case "pathetic".
In a one-line statement, police have told Newshub they will "take time" to consider the outcome of the court process.
Victims' advocate Ruth Money told Paul Henry on Tuesday morning the support Mr Filipo got was "disgraceful".
"We've got four innocent people, and we're focusing on this one guy's career, this one guy's potential."
Mr Filipo won a rugby contract straight out of high school, and Judge Davidson questioned whether the courts were "in the business of destroying people's career prospects".
Ms Money says the focus should have been on the ruined careers of those he attacked.
"We've got a model who needs to get plastic surgery; we've got a singer who's been threatened and punched in her throat; we've got a very promising rugby player who can never play again because not only did you knock him unconscious, you stomped on his head four times; and we've got a builder who can't work."
The prosecution doesn't feel it has a strong enough case to overturn the judgement on appeal. University of Otago law professor Mark Henaghan says this suggests the judge perhaps wasn't wrong not to convict Mr Filipo.
"If it's really out of line, the prosecution would appeal it fairly quickly," he told Paul Henry.
Prof Henaghan says judges have the discretion not to convict if the consequences would outweigh the gravity of the offending.
"With a discharge, there can still be consequences," he says. "The judge can still ask for reparation he can also ask for a community order where he may have to do community work. There are things that can be done. You don't walk away with no consequences."
But that's not how the families feel. Karen Odell, mother of victim Kelsey Odell, says Mr Filipo left them "for dead".
"If the police hadn't intervened, I don't think our children would be alive today."
Ms Money says Steve Tew and other top rugby officials need to "man up" and get rid of bullies in the game.
In a statement, Mr Tew said it was "not for us to comment on how he has been treated".
"He is getting the support he needs to make better decisions. We do not tolerate any behaviour by players that disrespects women or anyone for that matter.
"We believe young men, like Losi, are better off with rugby in their lives. Rugby provides a positive environment that helps equip players to manage the challenges they will face in life during and beyond their playing days."
NZ Rugby is "reviewing how we can improve the way we educate our players".
After Newshub uncovered this story, Wellington Rugby released a statement in which they defended themselves and Mr Filipo.
"Wellington Rugby would like to state clearly our organisation does not support violence in any form," chief executive Steve Rogers says.
The statement says while the organisation gave "generic information" to Mr Filipo's lawyer about what effects a conviction would have on a professional rugby player, it wasn't involved in the court proceedings and didn't know the full details of the case.
Wellington Rugby knew Mr Filipo was involved in an "off-field incident", but they put off any investigation of their own until the court case had finished.
Considering the court deemed a conviction wouldn't fit the seriousness of the crime, the organisation "down the path of providing Losi with a support network to assist in his rehabilitation".
Since the attacks, Mr Filipo completed 150 hours' voluntary work with a youth development group which promoted positive behaviour through sport and has been in regular counselling.
Mr Filipo's conviction comes not long after Nikolas Delegat, the teenage son of a wine mogul, avoided jail after knocking out a female police officer.
Prof Henaghan says while there's a perception that rugby players and the wealthy get preferential treatment in our justice system, the evidence doesn't back that up.
"There are cases where doctors ask about that, and the court's said 'no, sorry, you've got to suffer a conviction'. There are examples of lawyers, examples of league players.
"In one example it was a totally provoked assault - someone had stolen something from him, but he beat him up rather badly and the court said 'you have to suffer the consequences.'"
Ms Money says the families will take a little solace in the fact Mr Filipo's behaviour is now making headlines.
"At least we've this guy's name out there so you can google him."
A protest against his discharge has been organised for Friday evening in Wellington.