PHILADELPHIA (Reuters) - The U.S. Supreme Court is expected on Tuesday to issue its latest decision on the fate of Mumia Abu-Jamal, arguably America’s most famous death-row inmate, convicted of slaying a Philadelphia policeman, a crime he denies committing.

A demonstrator has "Free Mumia" painted on his sunglass lenses, outside the federal courthouse during the appeal of convicted murderer Mumia Abu Jamal in Philadelphia, Pennsylvania May 17, 2007. REUTERS/Tim Shaffer

The court is due to rule on an appeal by the Philadelphia district attorney who is seeking to have Abu-Jamal executed and bring an end to a decades-long legal saga the inmate, a former journalist, wrote about while in prison.

Abu-Jamal, now 55, was convicted in 1982 of killing officer Daniel Faulkner on December 9, 1981. He has become an international cause celebre for the anti-death penalty movement whose supporters argue strenuously he did not receive a fair trial.

His backers say he was framed by police, that prosecution witnesses were coerced into false testimony and that ballistics evidence shows Abu-Jamal did not shoot Faulkner but that the murder was committed by another man who fled the scene.

Supporters also claim that Abu-Jamal, who is black, was the victim of a racist and notoriously pro-prosecution trial judge, the now-deceased Albert Sabo, who was overheard to say, “Yeah, and I’m going to help them fry the nigger,” according to an affidavit by a court stenographer.

Faulkner’s widow, Maureen, and Philadelphia’s Fraternal Order of Police oppose any clemency for Abu-Jamal, arguing his conviction has been upheld repeatedly by numerous courts, including the Supreme Court, over three decades.

They note that bullet fragments taken from Faulkner’s body match the ammunition from the gun carried by Abu-Jamal who was earning his living as a taxi driver at the time of the killing.

If the Supreme Court rules in his favor, Abu-Jamal would get a new jury trial on the sentencing, but not his conviction.

But a defeat is likely to send the case back to an appeals court, whose ruling would be based on a new Supreme Court decision on jury instructions in another case, said his attorney, Robert R. Bryan.

Abu-Jamal has been in solitary confinement on death row since the conviction, and has been held since 1995 in a western Pennsylvania prison where he has written books and contributed to international journals and radio shows.

Outside the United States, Abu-Jamal’s backers include the human rights group Amnesty International, which in 2000 called for a new trial, arguing his conviction and sentence followed “contradictory and incomplete evidence” in a trial that failed to meet minimum international standards of justice.