Lawyers for imprisoned former media baron Conrad Black faced some tough questions by a panel of appeals court judges in Chicago Thursday as they tried to have his convictions for fraud and obstruction of justice overturned.

Former newspaper mogul Conrad Black arrives at the federal building in Chicago in December 2007 for sentencing on fraud and obstruction of justice convictions. (M. Spencer Green/Associated Press)

Black, who has been serving a 6½-year sentence at the Coleman minimum-security prison in Florida since March, wasn't present at the Seventh Circuit Court of Appeals. Instead, he was represented by his lawyers, Alan Dershowitz and Andrew Frey.

"The judges were very aggressive in the case of Conrad Black," said CBC reporter Mike Hornbrook, who spoke with people who watched the two-hour hearing unfold.

"I'm told by lawyers who were in the courtroom that they peppered Black's lawyers with questions … and showed a lot of skepticism about the points [Frey] had made in his legal brief."

After the court hearing, Frey told the Chicago Sun-Times that he felt Black's defence team raised "very strong issues." Frey told the paper the three judges on the appeals court panel "were doing their job of being skeptical."

Their decision is expected some time this summer.

A jury convicted Black on July 13, 2007, of obstructing justice and defrauding shareholders of his former newspaper company, Hollinger International Inc.

His three co-accused — Jack Boultbee, Peter Atkinson and Mark Kipnis — were also convicted of three counts of mail fraud. The judge later threw out one of the convictions against Kipnis.

Boultbee and Atkinson were handed shorter jail sentences of 27 months and 24 months, respectively. They are out on bond awaiting the outcome of their appeal. Kipnis was given probation.

Black's lawyers launched an appeal in March, contending that the U.S. government didn't generate enough evidence to prove Black defrauded anyone or attempted to hide documents.

If his appeal fails, Black can take the case to the full nine-judge appeals court and eventually ask for a review by the United States Supreme Court. If the appeals fail, Black will have to complete at least 85 per cent of his sentence before being eligible for parole.