David Harold Eastman could be eligible for millions of dollars in compensation for wrongful imprisonment if his conviction is overturned, based on payouts from other high-profile precedents.
But the figure would be subject to the court’s findings on the reasons for any wrongful conviction.
Eastman has spent 18 years, 11 months, and one day behind bars for the murder of assistant Australian Federal Police commissioner Colin Winchester in 1989.
A number of Canberra law firms said the scope of any potential payout for wrongful imprisonment would depend on factors such as duration of imprisonment, and the presence of negligence or malice of government officials.
Eastman has served more time than the recent high profile case of Perth man Andrew Mallard, who received a $3.25 million payout in 2009 after spending 12 years behind bars for a murder he did not commit.
Mr Mallard was eventually cleared in 2006 and received an ex gratia payment of $200,000 upon his release.
A government can make compensation payments ex gratia when it is prepared to compensate a person, but not admit liability.
Alice Lynne “Lindy” Chamberlain received $1.3 million in compensation in 1992 after she had been wrongly convicted of killing her nine-week old daughter, Azaria, at Uluru in 1980.
She spent about three years behind bars before after her sentence was overturned.
A coronial inquest in 2012 found a dingo had killed the child.
Aulich Civil principal Ben Aulich said the ACT was the only jurisdiction that has compensation available for wrongful conviction written into the Human Rights Act.
But Mr Aulich said the wording of the act – which says "If the section applies, the person has the right to be compensated ‘according to law' " - was ambiguous.
"We do not know what according to law means because I don’t know if it has been tested, I doubt it, but commentators think that it means full common law damages," Mr Aulich said.
"If that were the case, given how seriously the court takes the deprivation of a person’s liberty, his general damages would be huge.
"It’s very hard to make an assessment but it could be upwards of $5 million."
Defence lawyer Craig Lynch said Eastman would be eligible for a non gratia payment from the government upon release if acquitted.
Mr Lynch said Eastman could expect a small payment - worth at least tens-of-thousands of dollars - immediately upon release and a larger payment between $3 million to $5 million dollars at a later date.
"Or alternatively he can sue the government for a lot more," Mr Lynch said.
"But the figure would depend on the court’s findings."