It took him 19 years, countless court battles and millions in taxpayers' money, but on Friday he had his conviction quashed for one of Australia's most notorious police killings.

But the prospect of a retrial hung over Eastman's head as he was bundled from prison into the back of a car in fading light on Friday night.

It is not known where he will go or what he will do after almost two decades in prisons in the ACT and NSW.

What is clear, however, is that the interminable Eastman saga is not over.

The onus is on the Director of Public Prosecutions to decide whether Eastman will again face a jury over the alleged cold-blooded assassination of the ACT's police chief, Colin Stanley Winchester, on the night of January 10, 1989.

DPP Jon White is so far remaining tight-lipped about his plans, saying only that a new trial is under consideration.

Such a trial could not take place until next year at the earliest, and Eastman's lawyers can attempt to stay the proceedings before then.

Mr Winchester's family is ready for a second trial, says ACT Victims of Crime Commissioner John Hinchey, who spoke on their behalf after the decision on Friday.

"The Winchester family remain steadfast and resolute in their pursuit of justice for Colin Winchester and would support any retrial of David Eastman," he said.

Eastman's fate was decided by the full bench of the ACT Supreme Court on Friday, who found he did not receive a trial according to law.

The gunshot-residue analysis, so critical in linking Eastman to the murder scene at his 1995 trial, was discredited in Acting Justice Brian Martin's inquiry into his conviction, which handed down its findings earlier this year.

The full bench of the ACT Supreme Court said, given what had been uncovered, it could not allow the substantial miscarriage of justice to remain.

"It would be an affront to justice to permit the conviction to stand," the three judges wrote. "We have concluded that the conviction be quashed."

Eastman was bailed on strict conditions, including that he not contact the family of Mr Winchester, or a list of more than 200 individuals connected to the case. He also needs to give notice to leave the territory, and must reside as directed by ACT justice authorities.

Speaking on behalf of Eastman outside court, Legal Aid ACT chief executive John Boersig said the former public servant was looking forward to a "healthy and normal life", including re-employment.

"Throughout the long history of this case Mr Eastman has strenuously asserted his innocence," he said. "He is relieved finally to be exonerated and to regain his freedom after 19 years."

The prosecution has long argued that a strong circumstantial case remains against Eastman, even without the now-discredited forensics.

They have argued the evidence shows he had a clear motive, was linked to the murder weapon, was seen casing out the scene before the killing, and was unable to explain his whereabouts the next day.

Prosecutors say there is still evidence that Eastman made threats against Mr Winchester and uttered confessional-type statements, picked up on police bugs placed in his home.

Inquiry head Acting Justice Martin said he was "fairly certain" of Eastman's guilt, but had a nagging doubt. But Acting Justice Martin also found a second trial would be near impossible so many years later.

Witnesses have since died, some of the forensic evidence has been destroyed, and finding a jury free from the taint of prejudice after such extensive media coverage would be difficult at best.

Eastman's lawyers have said he would be at a severe disadvantage trying to defend the charges.

The full bench – Justices Steven Rares, Michael Wigney and Acting Justice Dennis Cowdroy – disagreed with the inquiry's findings, and said it was in the interests of justice to try Eastman again.

The judges found Eastman should not "escape having a jury decide whether or not he is guilty of that crime".

"Weighing all the relevant factors and considerations, we have concluded that the interests of justice require that we order a retrial," Justice Rares told the court.

Eastman's next court date is September 11, although he may return earlier to try to change his bail conditions.

Experts have said Eastman may struggle to readjust to life outside, after spending so long in the highly regimented and controlled environment of a prison.

The ACT Government has offered him support, including housing, meaning he will not go homeless.

He may eventually get a shot at compensation for wrongful imprisonment, which some lawyers have estimated could reach into the millions.

Terry O'Donnell, former lawyer and long-time campaigner for Eastman, also spoke to media outside the ACT Supreme Court.

"We're back to where we were in December 1992, we've still got one more step to go," he said. "I believe Mr Eastman has a strong defence case, that's if the matter was ever to go to trial again."

Asked what he would say to Colin Winchester's family, he replied: "It's not my business to say anything, but if someone else did do, the AFP haven't been a friend of Colin Winchester's family, because they've got the wrong man."