Justin ''Mully'' Williams was drunk, unlicensed, on bail, and fleeing NSW police in a stolen car when he ran a red light on Canberra Avenue, near the Monaro Highway turn-off, in March 2010.

The stolen car slammed into a vehicle carrying Scott Raymond Oppelaar, his partner Samantha Leanne Ford, and their three-month-old son Brody Oppelaar.

The Oppelaar's car was torn in half, and the three family members, including the baby, died instantly.

Williams and his passenger Skye Marree Webbe were pulled from the wreckage and taken to hospital, where he later died, and Ms Webbe survived with severe injuries.

NSW police officers had chased the car from Queanbeyan, after spotting Williams driving erratically, but communication problems prevented them from telling ACT Policing that they had entered the territory.

At the time, the case sparked a debate about police pursuits.

But the findings of an inquest, delivered this week by Coroner Peter Dingwall, laid no blame at the feet of the officers.

Instead, Mr Dingwall said Williams alone was at fault, describing his actions as the ''unlawful, reckless and selfish behaviour of a person who placed his desire to evade the police, and his ego, ahead of the lives of other road users''.

Williams was a serial car thief, whose bail conditions prohibited him from driving a car.

ACT Greens MLA Shane Rattenbury has campaigned for change to the territory's pursuit policy in recent years, saying that police should not chase drivers over minor crimes like car theft.

Mr Rattenbury acknowledged the coroner's findings completely cleared officers in the Williams crash, and said that was appropriate.

But he said the findings should be used to spark a new debate about pursuit policy in the ACT, and said he would soon be approaching Police Minister Simon Corbell.

Mr Rattenbury pointed to recent pursuit restrictions put in place in Queensland and South Australia, and a 2013 study by the Australian Institute of Criminology, which found 88 per cent of fatal pursuits in the past 12 years were related to the ''improper or unsafe'' operation of a motor vehicle.

''It does highlight the need for a dialogue about what protocols are acceptable to the community,'' Mr Rattenbury said.

''These are relatively minor offences that are leading to unwarranted deaths in the community, and my judgment is, that's not worth it,'' he said.

Mr Dingwall recommended that the government consider mandatory installation of immobilisers in cars likely to be targeted by thieves.

Police Minister Simon Corbell said that proposal would be considered, but said the ACT already had a voluntary engine immobiliser scheme, which hands out $200 vouchers for anyone with a car built in 2001 or earlier.

Williams' mother, Leanne Cosgrove, said she did not think immobilisers would make much real practical difference.

Mrs Cosgrove said she held no grudge against police for the chase, saying they were just doing their job, and that ''no one has a crystal ball''.

"They're out there to protect us,'' she said. "If someone had kidnapped my child, I would want them to chase that car.

"At the time, they don't know what they're dealing with. My view is they were just doing their job, what happened happened, the accident was horrific, it's just really unfortunate."

The inquest's findings were handed down following the end of the main hearing in 2011, which was followed by some additional evidence in 2012.

Mrs Cosgrove said the findings were nothing she hadn't expected, and said she didn't think they would make much of a difference.

"What's it going to change? It's not going to change what actually happened,'' she said.