The judge in the Luke Tipene murder trial has told the jury the teenage defendant can be found guilty even if the act was unplanned and "instantly regretted".
Vincent Angene Skeen, 17, has been on trial for the last two weeks in the High Court at Auckland and today Justice Mark Woolford summarised the case.
In the early hours of November 1, the defendant stabbed Mr Tipene in the neck with a broken bottle, after a Grey Lynn party saw dozens of teenagers spill onto the street.
A "glass dagger" pierced the victim's jugular vein and he died in hospital soon after.
At the outset, Skeen's lawyer Lorraine Smith - who was absent from court today because of illness - conceded her client had inflicted the fatal wound but did not have the requisite intent to be convicted of murder.
Justice Woolford said that would focus the jury's attention on one critical issue - intent.
"Has the Crown proved beyond reasonable doubt when Vincent Skeen stabbed Luke Tipene in the neck, he intended to kill Luke Tipene or to cause bodily injury which he knew was likely to cause his death and was reckless as to whether death ensued or not?" he said.
"There can still be murderous intent if it is unplanned and carried out in a rage or a frenzy . . . or if it is instantly regretted."
The judge outlined a number of factors the jury could look at when assessing what was going through Skeen's mind.
He suggested they consider the nature of the act itself, the type of weapon, how many times Mr Tipene was stabbed, what the teens were doing at the time, where on the body the stabs were directed and what force was used.
But Justice Woolford warned the jurors not to concern themselves with the fact Skeen had refused to give a police interview at the time or give evidence during trial.
"Society expects judges - you and me - to go about our business as calmly, dispassionately and clinically as possible," he said.
"You might have experienced an emotional response to what you've heard, especially about alcohol-fuelled violence among young people. Please put those emotions out of your mind."
Justice Woolford also warned the jury to be cautious when assessing the credibility and reliability of witnesses, 17 of whom had been on Great North Rd during the melee.
"Most had drunk a considerable amount of alcohol," he said.
The jury has retired to consider its verdict.