Leading insolvency accountant Nicky Tan has failed in his bid to have the Court of Appeal reverse its own earlier judgment in a debt restructuring case on the unusual ground that it breached natural justice.

But his firm, nTan Corporate Advisory, believes that despite losing last week, the judgment has cleared it of any implication that it acted improperly in its role as financial adviser to TT International Ltd, the local trading company behind electronics brand Akira.

More significantly, the Court of Appeal also departed from two of its previous decisions in 2009 and 2011 - which nTan had relied on in its application.

Instead, Singapore's highest court tightened its own remit as to when it can relook matters it had already ruled on before, to prevent the Court of Appeal from having to hear endless further appeals between the same litigants arguing the same issues over and over again.

Acknowledging that the apex court was changing course, Chief Justice Sundaresh Menon, who wrote the main judgment for the five-judge panel, said this was needed to "minimise unnecessary strain on the court's resources".

He added that this will also give litigants greater assurance that they can plan their affairs on judicial decisions which were made, even if the decisions contained some error.

The case had its roots in the global financial crisis of 2008. Caught up in the crisis, Singapore Exchange-listed TT International in 2008 hired nTan as an independent financial adviser to deal with its debtors, who were threatening to sue. The debts amounted to some $485 million and three banks were involved. The main dispute in the latest appeal arose over the way nTan, which has a track record of turning around failing companies, was to be paid for its services. Part of nTan's payment agreement with TT International included a "value-added fee" or VAF.

The VAF was essentially a success fee based on a percentage of the debt owed by TT to its creditors which nTan was able to get waived or written off, or converted to equity, through a restructuring scheme that nTan would put in place.

So the greater the debt nTan managed to get waived off, the more it would be paid.

The scheme was given the green light by the Court of Appeal in October 2010, as required by Singapore's Companies Act, after it was approved by creditors, who accounted for more than 75 per cent of the value of debt.

As part of the scheme, oversight was handed to a group of three managers - including Mr Tan, nTan's CEO and controlling shareholder, and two other nTan staff.

The dissenting creditors, which included DBS Bank, Habib Bank and OCBC and represented by Rajah & Tann lawyers led by Senior Counsel Lee Eng Beng, said this raised a conflict of interest.

They also alleged that they did not know of the existence of the VAF. All these were played out through a series of correspondence between the different parties and the then Court of Appeal.

In a September 2012 decision, the Court of Appeal agreed with the dissenting creditors but believed that setting aside the scheme could harm them and the company further. So the court decided to change it instead.

It ruled that nTan was not entitled to the full VAF sum, which the scheme managers put at between $28.4 million and $31.8 million. Instead, nTan, represented by Allen & Gledhill lawyers led by Senior Counsel Edwin Tong, would have to work with the creditors and agree on an acceptable fee.

Failing that, the High Court would set the amount.

Aggrieved by this decision - especially after TT International had successfully had its debts restructured and was back to profitability - nTan appealed.

Highlighting the importance and unusual nature of the case, it was heard before a panel of five judges, when the usual is three.

One of the arguments nTan's lawyers raised was that it never got the chance to present its case in court as the issues were detailed through letters, and that this breached natural justice.

But CJ Menon held that the correspondence did afford nTan enough opportunity to give its side. Further, the current court would have been more sympathetic had the earlier decision raised doubts over the firm's integrity.

But this never happened, he pointed out. While nTan may have been uncomfortable with statements such as "the greater the pain endured' by the scheme creditors, the greater its own gain", there was never any suggestion that its staff had acted dishonestly or in bad faith.

This was shown by the fact that the court did not remove any of the scheme managers when it could have.

CJ Menon agreed that "there is some force" in another argument put up by nTan - that the earlier court had no power to rewrite the scheme into something other than what the creditors had originally signed up to.

But even if an error was made, nTan was precluded from bringing it up again as it goes against the legal principle that a matter already judged is final, better known by the Latin term res judicata.

CJ Menon rejected previous case law which allowed for a broad exception to this principle. He made it clear that a litigant can only re-argue a point in narrow circumstances, such as when the decision was clearly wrong and great injustice would result if it was allowed to stand. "In the final analysis, the public interest in the finality of litigation must prevail," he wrote.

When queried, an nTan spokesman told The Straits Times that the firm was "gratified that the Court of Appeal made clear that its earlier decision had not found that it had acted against the interests of the creditors and that no finding of dishonesty or bad faith was made".

He added that nTan fully respects the court's position that the public interest in the finality of litigation must prevail.

A case note published in Singapore Law Watch on Tuesday highlighted the case's importance.

A senior practising lawyer not involved in the case said the Court of Appeal, in departing from two of its own previous decisions, "has made new law and underscored the need for res judicata in Singapore".

As for nTan, he said the ruling has clarified "that the earlier decision did not make any adverse findings of fact against its professional reputation and standing.

"I anticipate that this was one of the key reasons why nTan had made the application to set aside the decision in the first place and I expect that nTan will be pleased with that."

CJ Menon also ordered a separate hearing to consider the question of costs and any "consequential orders" - thought to include the quantum of nTan's fee which remains unpaid.