The family of a couple and their unborn child killed by a teenage driver say Queensland authorities have "more blood on their hands" after three people died in a multi-car crash.
Russell Field demanded a tougher youth justice stance after an attempt to increase a 10-year sentence for the teenager who fatally hit his son and the 37-year-old's pregnant partner in a stolen four-wheel-drive was dismissed.
The teen's push to reduce his sentence also failed in Queensland's Court of Appeal on Tuesday.
The teen was drunk and high on cannabis when he struck Matthew Field and six months' pregnant Kate Leadbetter, 31, with the stolen Landcruiser while they were walking their dogs near Brisbane on Australia Day 2021.
More than two years later, a teenager has been charged with three counts of dangerous driving causing death after allegedly crashing a stolen Mercedes in the regional Queensland town of Maryborough on Sunday night.
"It is tragic that this has happened again," Russell Field told media outside court on Tuesday.
"The premier and the lawmakers of the state have more blood on their hands now because nothing was done earlier."
Mr Field supported mandatory minimum sentences for juvenile offenders.
"I stand here today and I guarantee you another accident like this will happen again, again and again," he said.
"What's got to happen for them to change something and get these kids understanding what they can and can't do?
"How many more people have to die?"
Matthew Field's mother Ann said she understood judges were bound by the legislation when they ruled the 10-year sentence was appropriate.
But she added: "If the premier thinks these laws are adequate I think the people need to stand up and do something about it."
The teen who killed Matthew Field and Ms Leadbetter received the 10-year term after pleading guilty to a string of charges including two counts of manslaughter.
But the teen - who cannot be named because he was 17 at the time of the offences - will be eligible for release after serving six years.
The families of the victims described the sentence as "grossly inadequate" and Queensland Attorney-General Shannon Fentiman launched an appeal in June 2022.
The appeal was pushing for a sentence of up to 14 years but it was dismissed on Tuesday.
"What's got to happen for anybody to be serving the maximum sentence?" Mr Field said.
The teen's lawyers argued the sentence was excessive but their application for leave to appeal was refused.
"The sentencing judge was fully cognisant of the seriousness of the respondent's offending and sentenced the respondent for the manslaughter offences by reference to the maximum of detention for life," the Court of Appeal judges wrote on Tuesday.
"The Attorney (-General) has failed to show that this is an exceptional case which justifies a departure on appeal from the submissions made by the prosecutor before the sentencing judge... or that the sentence imposed on the respondent was 'unreasonable and plainly unjust'."
© AAP 2023