A Ballarat bus driver jailed for injuring six people when he crashed into a notorious Melbourne bridge could walk free from jail.

Jack Aston’s six convictions for negligently causing serious injury were overturned by the Court of Appeal on Monday, when it was determined prosecutors made a mistake by not raising with the judge a less serious alternative charge of dangerous driving.

Instead the court convicted Aston of six counts of dangerous driving causing serious injury.

The maximum penalty is double that of the less serious charge, so he will be re-sentenced.

His lawyer Catherine Boston asked that Aston’s prison sentence be replaced with a community corrections order, focusing on the mental health conditions he has developed since crashing into the Montague Street Bridge at South Melbourne in February 2016.

Justice Phillip Priest said Aston was to be assessed for the order but would remain behind bars until he is re-sentenced in “a reasonably short time”.

Aston was jailed for five years and three months, with a non-parole period of two-and-a-half years in December.

Six of Aston’s 14 passengers suffered a range of injuries, including spinal fractures, glass particles in their face, scalp injuries and a broken neck.

On Monday, Ms Boston said the maximum penalty of the dangerous driving charge was half that of the negligence charge and the law required it to have been be considered as an alternative.

Ms Boston said she wasn’t suggesting there had been a deliberate failure by anybody in the trial, but that without the lesser charge being raised by prosecutors, they had failed to meet their legal obligations.

Justice Phillip Priest was critical of the failure.

“This is basic trial practice,” he said.

“I’d expect a prosecutor to know, defence to know and, with all respect, the judge should have known.”

Crown prosecutor Fran Dalziel QC had initially asked that Aston face a retrial.

But she withdrew that claim on Monday, accepting the prosecutor had contributed to the error.

She said it remained possible Aston would again be convicted of the negligence offence, but it would not be in the interest of justice to pursue a new trial.

-AAP