Conrad Black, who is in a Florida prison serving a 6½-year sentence for fraud and obstruction of justice, has asked the U.S. Supreme Court to hear his case in a last-ditch effort to overturn his conviction.

The former CEO of Hollinger International wants the country's highest court to review his guilty verdict to assess whether the prosecution's argument that Black deprived shareholders of the honest services they were owed is a legitimate one.

But Jacob Frenkel, a former U.S. prosecutor who has followed the case, said Friday the bid is unlikely to succeed.

Unlike lower courts, the Supreme Court must agree to hear a case, which means Black's petition is fighting to get through a door "with such a small crack that the likelihood of getting in is negligible," Frenkel said.

"Statistically, the likelihood of the Supreme Court agreeing to review is marginally better than the likelihood his sentence will be commuted — and both are around nil."

A decision this week to uphold former Enron Corp. CEO Jeff Skilling's convictions for his role in the energy giant's collapse has also significantly damaged Black's chances of the Supreme Court even considering this issue, Frenkel said.

Toronto lawyer James Morton said he would "be astonished" if the Supreme Court accepted Black's petition.

"The jury legitimately could have found that there was theft of company money, so there is a supportable basis for the jury's decision which is not tainted in any way by any legal argument," Morton said.

"Since the jury's decision is supportable on the facts, why would the Supreme Court take this case where it's muddy to clarify an area of law that's really not all that unclear anyway?"

In a joint petition to the Supreme Court with Black co-defendants John Boultbee and Mark Kipnis, Black's lawyer Miguel Estrada said the "petitioners were convicted ... based on an instruction that permitted the jury to find a 'scheme to defraud' … by determining that petitioners either stole the company's money, or deprived the company or its shareholders of their 'right' to petitioners' 'honest services.' "

"The first theory would have required jurors to find that petitioners were guilty of theft pure and simple," said the petition filed Friday.

Appeal to White House for commutation

"But the second theory permitted convictions even if the jurors believed that the money was rightly petitioners' and that they therefore inflicted no pecuniary or other economic injury on their employer."

Black was convicted last year of a $6.1-million fraud and obstruction of justice related to his eight-year spell as head of Hollinger International Inc.

He has requested a commutation of sentence from U.S. President George W. Bush after unsuccessfully appealing his case.

Bush issued 14 pardons and commuted two sentences in November — all for small-time crimes such as minor drug offences, tax evasion and unauthorized use of food stamps.

Black wasn't on that list but he can hold out hope for a commutation that could reduce or eliminate his sentence until Barack Obama takes over the presidency Jan. 20.

Still, observers say recent media attention surrounding the impeachment of Illinois Gov. Rod Blagojevich over allegations he tried to sell Obama's vacant Senate seat will make it much harder for Bush to commute the sentence.

"All of a sudden [Black prosecutor and U.S. Attorney] Patrick Fitzgerald is championing anti-corruption with his investigation of the Illinois governor," Frenkel said.

"And the fact that it's the same prosecutor, I'm not sure the president wants to leave challenging him that openly."

Bush has already commuted the 30-month prison sentence handed to his former aide Lewis (Scooter) Libby, who was convicted of perjury and obstruction of justice last year for lying to a grand jury about a White House leak, in a case also prosecuted by Fitzgerald.