A Queensland teenager who killed a young couple and their unborn child is facing an appeal against his sentence on the grounds it was manifestly inadequate.
The families of victims Matthew Field, 37, and Kate Leadbetter, 31, described the 10-year jail sentence handed to the 18-year-old as "grossly inadequate".
The couple and their unborn child were killed in a collision with a stolen car while out walking their dogs in suburban Brisbane in January last year.
Attorney-General Shannon Fentiman has now signed a notice of appeal to be lodged by the director of public prosecutions on Thursday afternoon.
"I have listened, I have taken the advice from the director of public prosecutions and now I am appealing this matter," Ms Fentiman said.
There are grounds for appeal, given the judge determined the manslaughter offence was heinous, meaning the sentence could have been more than 10 years, the attorney-general said.
Matthew's parents Ann and Russell Field welcomed the appeal but continue to push for law reform.
"We thank the Attorney-General and hope the appeal is swift and results in a more appropriate sentence in line with the community's expectations for the three beautiful lives that were so tragically cut short, as well as the countless others that have been destroyed as a result," the couple said in a statement.
"The deaths of Matthew, Kate and Miles must not be in vain."
Mr and Mrs Field said the tragedy must force change in youth justice laws leading to tougher juvenile sentences.
"They don't only owe it to Matthew, Kate and Miles - they owe it to every family who has lost a loved one or suffered in some way as a result of a repeat juvenile offender.
"This is not a political issue, it is a moral issue, every family deserves justice."
In the wake of the tragedy Queensland reversed a presumption of bail for certain young offenders who commit serious crimes, but the Liberal National opposition wants more changes to youth justice laws.
"We don't want other families to go through this ... we want to see a Youth Justice Act that stops this revolving door," Opposition Leader David Crisafulli said.
The LNP has been calling for the return of breach of bail as an offence for young people, but Ms Fentiman said it doesn't work.
She said about 90 per cent of those found guilty went on to commit an offence within a year.
The guilty driver, who cannot be named because he was 17 at the time of the crash, was originally charged with murder, before pleading guilty to two counts of manslaughter.
In sentencing, Justice Martin Burns took into account the teen's protracted period of extremely dangerous driving that culminated in a grossly negligent final act, regarding the manslaughter offences as "particularly heinous".
But the teenager had to be sentenced as a child, with the "grave nature of offending" balanced by his youth.
The sentence was also based on the teenager not intending to kill or do grievous bodily harm.
As it stands, he must serve six years of the 10-year sentence behind bars.
The matter is now before Queensland's Court of Appeal.
