TORONTO - U.S. federal prosecutors say Conrad Black's fraud convictions should be upheld on appeal because they did not rely on a controversial "honest services" law that was struck down by the U.S. Supreme Court and triggered a re-examination of the former media baron's case.

"Never did the government argue that there was an independent, stand-alone, honest services violation," U.S. attorney Patrick Fitzgerald wrote in a filing to the U.S. Court of Appeals released Tuesday.

A Supreme Court ruling in June narrowed the scope of "honest services," limiting it to bribes or kickbacks and instructed lower courts to review Black's convictions in light of the new interpretation.

Defence lawyers contend that the interpretation of the honest services law was key to Black's conviction on three fraud charges, along with one count of obstruction of justice.

But in the filing, Fitzgerald said the prosecution had not used honest services arguments to convict Black in the 2007 case that centred on US$5.5 million in so-called "non-compete" payments involving the sale of newspaper assets of Hollinger International.

"The government never proposed such a theory to the jury and instead presented evidence that the money was Hollinger's, was stolen, and was disguised as non-competition payments ... And that theft, of course, comprised a money-fraud."

Defence and prosecution submissions will be reviewed by a panel of three appellate circuit judges led by Judge Richard Posner, who presided over Black's last appeal and took only 20 days to reach a decision.

At issue is the right to honest services-- a concept developed in the 1970s to convict corrupt politicians seen as defrauding the public by failing to provide "honest services" as public servants-- and whether it should apply to private conduct.

Black, the former chairman and chief executive of the Hollinger International media company, was convicted of siphoning money out of the company and falsely claiming executives were getting non-compete payments from buyers of Hollinger assets.

His lawyers say the $5.5 million that he and other executives received from a Hollinger subsidiary was money that they were legitimately owed and they cannot be convicted of fraud when they did no harm to the company.

Black's defence lawyers have argued since his July 2007 trial that the government misled the jury in instructing it that the honest services law -- a favourite tool of prosecutors in white-collar and public corruption cases -- be applied in Black's case. They maintain all of Black's convictions should be dropped because of the error.

Black's lawyer Miguel Estrada argued that it at least one of the jurors in Black's trial likely used the concept of honest services fraud to justify Black's convictions for fraud and obstruction of justice.

But Fitzgerald, who won the 2007 conviction against Black, said the "instructional error" to the jury on the honest services law was "harmless beyond a reasonable doubt" because it was not the basis for Black's fraud convictions.

"The government's honest services arguments were based on the defendants' thefts of money, which support the money-fraud convictions," he wrote, adding that the error also had no bearing on Black's obstruction of justice conviction.

"The evidence of the obstruction, and the defendant's corrupt intent, was strong," Fitzgerald argued.

Fitzgerald said if the fraud charges were thrown out and the obstruction of justice charge against Black upheld, he should be resentenced because the fraud charges contributed to his original 6 1/2 year prison term.

"If (and only if) the fraud convictions are vacated (and they should not be) -- then there should be a remand for resentencing on the obstruction conviction," Fitzgerald wrote.

A re-evaluation of his sentence, of which he has already served 2 1/2 years, means Black could be released well ahead of his projected Oct. 30, 2013 release date.

The filings also apply to the remaining convictions against co-defendants Peter Atkinson, John Boultbee and Mark Kipnis.

Atkinson and Boultbee, both Canadian executives of Hollinger, received two years and 27 months respectively. Chicago attorney Mark Kipnis, a former Hollinger employee, was placed on probation with six months of house arrest.

All four men were found not guilty on a majority of the fraud charges against them but convicted on some charges. Black was the only one charged with obstruction for removing boxes out of his Toronto office, contrary to an Ontario court order, making his sentence significantly lengthier than that of his three co-defendants.

Montreal-born Black, who was forced to renounce his Canadian citizenship in 2001 in order to accept an invitation to join the British House of Lords as Lord Black of Crossharbour, is currently free on bail after serving more than two years in a Florida prison.

Black recently dropped a request to return to Canada and will remain in the United States while the appeal that could bring a final resolution to his case goes ahead.

Black is expected to return to a Chicago court Sept. 20 for a bail update, where he could make a request to return to Canada again.

He is still facing several civil suits, including a $71-million lawsuit by the U.S. Internal Revenue Service for alleged unpaid taxes, which he has challenged.

Black was head of the world's third-largest newspaper empire in terms of circulation until he was ousted in 2003 following an internal investigation initiated by Black in response to shareholder complaints.

Hollinger once owned the Chicago Sun-Times, the London Daily Telegraph, the Jerusalem Post and hundreds of newspapers in the U.S. and Canada.