Tamatea Briggs, right, was the driver in a Woolston liquor store robbery. He has turned his life around and was discharged without conviction.

A year after being involved in the aftermath of a violent liquor shop robbery, a Christchurch teenage is seen as having the potential to become "a great leader".

Tamatea Lorenzo Briggs was granted a discharge without conviction on charges of being an accessory after the fact to robbery, assault, unlawfully taking a car from the assault victim, and driving while forbidden.

The discharge means the 17-year-old will not face a seven-year stand-down before he can apply to join the army.

Briggs has completed one military programme and finished a Limited Service Volunteer course at Burnham where he graduated with merit – the highest rating he could achieve.

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Christchurch District Court Judge Jane Farish granted the discharge at his sentencing on Wednesday, saying how unusual it was for all authorities involved to agree there should be no conviction.

The discharge was in the community's best interests, the judge said.

"The army think you will make a great leader, and will be someone who will be able to lead men and be a positive role model for other young people, particularly those who have had a disadvantaged upbringing such as yourself."

Briggs was drinking with a group who decided to go to a Woolston liquor shop to get more alcohol. He drove them, but they were refused alcohol because they were under-age and could not provide identification.

Two youths then smashed bottles over the head of the shop assistant, and Briggs drove them away afterwards.

Judge Farish accepted Briggs had not known the associates were going to use violence. The younger offenders have been dealt with in the Youth Court.

She said Briggs had always been seen as having potential, even though his parents had chosen to abuse alcohol.

The judge granted the discharge, but imposed 150 hours of community work. "There are agencies that would really benefit from your ability and your skills," she said.

She hoped he would apologise to the liquor shop worker who was bashed and robbed.

She noted he was remanded in custody for four months after his arrest, which had been the wake-up call he needed and his turn-around had been a "remarkable achievement".

"You said then that this wasn't going to be your life."

Briggs' lawyer declined to comment after the hearing.