According to the stuff,co.nz website, the man, who is also a witness to the attack, filmed the accused leaving court on Thursday on his cellphone and posted it to YouTube and Facebook. He also published their names online.
He told One News he had no intention of removing the video, which still remains on YouTube. So far, it has had more than 7600 views.
Detective Senior Sergeant Brian Archer said police were aware of the video circulating online and "further enquiries into this matter are continuing".
Canterbury-Westland branch president of the Law Society Rachel Dunningham said anyone who breached a suppression order could face up to a $50 000 fine or a maximum of six months in prison.
Dunningham said they could be charged with breaching the Criminal Procedure Act or held in contempt of court.
She said suppression orders were made for good reasons. "The real risk of prejudice to a fair trial. Hardship for victims of the offence. Endangering the safety of a person.
"It could be any combination of circumstances. The court doesn't make them lightly."
She said people needed to be aware everyone was "bound" by name suppression orders, not just the media.
"With the internet now people have powerful publication tools at their fingertips and can cause just as much damage to a fair trial as mainstream media [by breaching a suppression order]."
Canterbury University's School of Law Professor Ursula Cheer said the fact the breach seemed "very deliberate" made it a serious offence.
"If you knowingly breach a suppression order you're liable to a more serious penalty."
She said it was "obviously a possibility" the man could be charged for breaching the suppression order.
Cheer said the fact the judge issued the interim suppression order despite the men being named in The Press earlier that day, showed the decision was not made lightly.
The accused, 37-year-old builder and his 20-year-old nephew, a carpetlayer, are to reappear in court next Thursday.