Ontario’s top court has ordered a new trial for a young man convicted of first-degree murder in a highway crash that claimed the life of a York Region police officer.

The man, who was 15 at the time of the incident in 2011 and therefore cannot be named, was rendered quadriplegic in the crash that killed Const. Garrett Styles.

He was sentenced in 2015 to a conditional supervision order for nine years, after the trial judge found he was already effectively serving a life sentence as a result of his physical state and that he had been rehabilitated.

The man appealed his conviction, alleging the trial judge made several legal errors and that the first-degree murder verdict was unreasonable.

In a ruling released Tuesday, the appeal court found the trial judge erred in failing to caution jurors that they should consider the accused’s age and level of maturity at the time of the incident in determining whether he knew his actions were likely to cause Styles’ death.

The appellant had taken his parents’ van late at night in June 2011 to go driving with friends — despite having no licence — when Styles pulled them over in East Gwillimbury, Ont.

Court heard Styles sought to impound the van and repeatedly asked the teen driver to step out of the vehicle, eventually reaching inside to unbuckle his seatbelt.

The van then suddenly accelerated and dragged the officer about 300 metres before veering off the road and landing on top of him.

At the heart of the trial was whether the 15-year-old meant to drive away, as the Crown alleged, or did so accidentally while in a state of panic, as the defence argued.