"They (the Mongrel Mob members) stripped him of his patch and took it as a trophy," Stuart said.
The court was told the two mobsters had spotted Lui riding his Harley Davidson and followed him.
The driver of the maroon Holden Calais car was Hemi Rapata Meihana Cahill, 30.
In court on Monday, Cahill pleaded not guilty to being party to a murder and assault using a motor vehicle as a weapon.
However, he pleaded guilty to the aggravated robbery of Lui's Outlaws patch.
Stuart told the jury that Cahill's associate, the car's passenger, Belmont Sonny Freedom Eruiti Te Aonui-Tawhai, 23, had already pleaded guilty to aggravated robbery.
He said Te Aonui-Tawhai had also pleaded guilty to murder and assault with a weapon – the two charges which Cahill has denied.
Stuart said the Crown acknowledged that Cahill did not strike the fatal knife blows himself. But he could be liable for murder because of "group plan" or "common intention".
"When you help out, or are part of a group plan, you can be guilty of a crime as a party," Stuart said.
Defence counsel Eric Forster said that Cahill did not contemplate causing Lui's death, and that he did not anticipate his associate, Te Aonui-Tawhai, would do so either.
"We shouldn't be criminally responsible for acts we don't anticipate, intend or contemplate," Forster said.
He said Cahill was not guilty of assault with a weapon because he did not intend to strike Lui with the car.
He was not guilty of murder "because he did not have murderous intent".
Cahill's trial before Justice Christine Grice and a jury of seven women and five men is expected to last up to two weeks.
