The family of a schoolboy who died after a violent incident at rugby training are calling for a manslaughter charge to be laid after the Coroner found the actions of another teen was the significant factor in his death.

LISTEN ABOVE: LAWYER FOR THE DUDLEY FAMILY NIKKI PENDER SPOKE TO LARRY WILLIAMS

Stephen Eruwera Dudley died on June 6 2013 after he was punched repeatedly by two teenage brothers at a West Auckland rugby field.

Stephen, 15, suffered cardiac arrhythmia during the assault and was rushed to Auckland City Hospital.

Despite frantic attempts to revive him, he was pronounced dead on arrival.

The brothers were initially charged with manslaughter.

But after medical examinations showed an undiagnosed heart condition contributed to his Stephen's death the Crown withdrew the charge.

Both boys then pleaded guilty to assaulting Stephen and were discharged without conviction and granted name suppression.

Last year, just after third anniversary of Stephen's death Coroner Gordon Matenga held an inquest.

Today he released his report, and found that while Stephen may have had an underlying heart condition - his death was the direct result of "stress associated with physical assault".

"(The brothers) the assaulted Stephen by punching him several times to his body," Coroner Matenga said.

"Stephen did not retaliate in any way."

"If the (undiagnosed condition) was the underlying cause... why did it not cause an arrhythmia earlier that day, or during the pre-training argument between (the 16-year-old) and Stephen where there was emotional and psychological stress; or during training with the physical stress that placed on Stephen?

"The assault, consisting of  heavy blow to the neck and then a series of punches to the torso, must have been the factor which precipitated the arrhythmia.

Coroner Matenga said the assault preceded Stephen's collapse and was "the most significant factor which lead to the arrhythmia."

Lawyer Nikki Pender, who represents the Dudley family, welcomed the inquest findings.

"Finally, someone independent has looked at all the evidence and given them answers as to what happened the day Stephen died," she said.

"The Dudley family will be asking the Solicitor General to review this case in light of the Coroner's findings with the aim of laying a manslaughter charge."

Pender said the reason the manslaughter charge was withdrawan by the Crown after the 2013 incident was "that it could not be determined that the assault was a substantial or operative cause of Stephen's death".

"That reason has now been debunked by the Coroner's findings which is why the Dudley family want the Solicitor General to consider whether a manslaughter charge could not be brought.

"The criminal justice system has let down everyone involved with this case by failing to lay charges which properly reflect the seriousness of the circumstances.

"As a result, Stephen's death has been trivialised."

Pender was pleased that the Coroner had ruled Stephen was assaulted, when previously the incident had been labeleed a "schoolyard fight".

"The previous narrative was that any assault was in the context of a "schoolyard fight", implying that Stephen shared some of the blame,' she said.

"Stephen was assaulted by being punched heavily to the side of the neck by the brother of the other boy," she pointed out.

"Stephen was then repeatedly assaulted around his torso by the two brothers while a team mate held him up and tried to protect him.

"Stephen himself did not retaliate in any way."

Pender said the Dudley family were appreciative of the Coroner's ruling and his recommendations that more be done in schools to encourage CPR training and the use of Automated External Defibrillators by students.