Two police officers found guilty of striking a drunk teenager have been convicted.

Alan Michael Douglas and Gareth John Needham appeared at the Auckland District Court today for sentence.

The two West Auckland constables were found guilty at their trial last December of assaulting then 18 year-old Joshua Hart.

Mr Hart had been drinking with up to 50 young people in a park when police were called to break up the party and send them home.

Mr Hart was abusive to police after his drink was knocked out of his hands by Mr Needham.

Needham struck him two times as he brought him to the ground and handcuffed him.

Mr Hart was then led in handcuffs to a spot in the park where other police officers were waiting, including Douglas.

Douglas was found guilty of striking Mr Hart twice in the face while the teen was handcuffed.

The two police officers had applied for a discharge without conviction after a restorative justice hearing with Mr Hart.

Mr Hart did not oppose the discharge without conviction.

However, Judge Allison Sinclair declined the application.

She found that the consequences of a conviction would not be out of all proportion to the offending.

She told Douglas that while the offending was at the lower end of the scale, "it was a gratuitous use of violence on someone that was handcuffed at the time during the course of Mr Douglas carrying out his duties as a police officer."

Judge Sinclair also fined Douglas $600.

Judge Sinclair did not fine Needham.

"As a police officer, I accept an entry of a conviction is a significant penalty in itself."

Needham was in the news last week when he gave evidence at the Aisling Symes inquest.

Needham was one of the first police officers on the scene when two year-old Aisling was reported missing in October, 2009.

He found a manhole slightly ajar and checked the manhole but saw no sign of Aisling.

Needham did not tell his superiors about finding the manhole cover and Aisling was found 36m down the stormwater pipe seven days later.