The Commonwealth had asked the ACT Court of Appeal to order the group pay security of costs – on the grounds they did not have enough money to pay costs if the court dismissed their appeal – before the matter could continue.

Justice John Burns on Tuesday found the appellants could not afford the $70 million they had already been ordered to repay, and could not cover the cost of the appeal if they lost.

But Justice Burns also found their financial situation had been the result of the court ordering them to pay the federal government tens of millions in compensation

The judge dismissed the Commonwealth's application, saying their right to appeal should not be blocked by a demand they stump up the cash before the court battle.

"There must be a real prospect of the appellants being unable to pursue the appeal if an order for security for costs is made," Justice Burns said.

"I have weighed up all of the considerations relevant to the application for security for costs, many of which favour the making of the order, but I am ultimately persuaded that I should not make the order.

"The deciding factors are, the fact that the appellants' impecuniosity arises from the orders under appeal, [and] the appellants' right to proceed with their appeal should not be effectively denied to them by reason of an order for security for costs."

The marathon legal battle, now in its 16th year, started in 1998 when about $8.72 million of taxpayers' money was wrongly transferred to companies linked to Davis Samuel Corporate Advisory Services.

The Commonwealth attempted to recoup the costs and launched a failed criminal prosecution of 26 Davis Samuel investors.

The group responded with a $4.3 billion civil claim against the Commonwealth, arguing they lost that amount when they could not pioneer a capital-raising plan in Australia.

The complex tangle of claims and counter-claims were heard in the ACT Supreme Court in 2008.

Justice Richard Refshauge reserved his decision for five years before he struck out the billion dollar claim, finding in 2013 that the original $8.725 million payment had been void and illegal.

Late last year, the judge ordered 13 of the defendants to pay the Commonwealth almost $70 million in compensation.

The group has appealed the decision to the ACT Court of Appeal, citing 88 grounds, including delay.

But lawyers for the Commonwealth attempted to block the appeal by applying the court for the group to pay a security up front to cover court costs that could be incurred by the action.

"At least some of the appeal grounds are arguable," Justice Burns noted in his decision.