A teenager who embarked on a random bashing spree on Auckland's North Shore in 2008 his lost his appeal against his conviction and 14-year prison sentence.

Ruaumoko Taiapa, 19, was one of four young men who attacked two couples with baseball bats and metal bars leaving them with severe head injuries.

Dismissing the appeal, Court of Appeal Justice Lynton Stevens said Taiapa should not have been in Auckland because he was on strict parole conditions for assaulting police.

He also bashed another Auckland woman in the head with a baseball bat only five days before the random bashing.

The three others given jail sentences ranging from 11 to nine years.

Taiapa's mother Kiriana Taiapa was sentenced to four months detention for being an accessory after the fact after hiding weapons used in the attack following her son's arrest.