Washington ( CNN ) -- The Supreme Court has tossed out a lower court ruling that nullified the death sentence for former Black Panther Mumia Abu-Jamal , who was convicted of gunning down a Philadelphia , Pennsylvania , police officer more than 28 years ago . He has been an outspoken activist from behind bars , claiming there were procedural errors during his capital sentencing , and that too few blacks were on the jury . Pennsylvania officials were appealing a federal court ruling on the sentencing question that went in Abu-Jamal 's favor in 2008 . The justices made their announcement Monday , ordering a federal appeals court to revisit its earlier ruling granting a new sentencing hearing . The high court last year denied Abu-Jamal 's separate petition for a new trial . The appeals court now has the option of reimposing the death sentence or ordering a new federal trial to hear other claims of injustice raised by Abu-Jamal . The case has attracted international attention , amid charges of prosecutorial misconduct and the inmate 's outspoken personality . The onetime radio reporter and cab driver has been a divisive figure , with many prominent supporters arguing that racism pervaded his trial . Others countered Abu-Jamal is using his skin color to escape responsibility for his actions . They say he has provoked community unrest for years with his provocative writings and advocacy . He was convicted for the December 9 , 1981 , murder of Officer Daniel Faulkner , 25 , in Philadelphia . Faulkner had pulled over Abu-Jamal 's brother in a late-night traffic stop . Witnesses said Abu-Jamal , who was nearby , ran over and shot the policeman in the back and in the head . Abu-Jamal , once known as Wesley Cook , was wounded in the encounter and later confessed to the killing , according to other witness testimony . Incarcerated for nearly three decades , Abu-Jamal has been an active critic of the criminal justice system . On a Web site created by friends last year to promote the release of Abu-Jamal 's latest book , he wrote : `` This is the story of law learned , not in the ivory towers of multibillion-dollar endowed universities but in the bowels of the slave ship , in the hidden , dank dungeons of America . '' Chief defense attorney Robert Bryan had made jury selection a key component in the various appeals filed over the years . Ten whites and two blacks made up the original jury panel that sentenced Abu-Jamal to death . Faulkner 's widow , Maureen , has written `` Murdered by Mumia : A Life Sentence of Loss , Pain and Injustice , '' a book in the slain officer 's memory . In it she writes about her efforts to hold Abu-Jamal accountable for his crimes . A three-judge panel of the 3rd U.S . Circuit Court of Appeals had kept the murder conviction in place , but ordered a new capital sentencing hearing . That court ultimately concluded the jury was improperly instructed on how to weigh `` mitigating factors '' offered by the defense that might have kept Abu-Jamal off death row . Pennsylvania law at the time said jurors did not have to unanimously agree on a mitigating circumstance , such as the fact that Abu-Jamal had no prior criminal record . Months before that ruling , oral arguments on the issue were contentious . Faulkner 's widow and Abu-Jamal 's brother attended , and demonstrations on both sides were held outside the courtroom in downtown Philadelphia . The justices in the order on Monday cited their ruling last week on a separate capital case on when capital defendants can cite an inadequate defense in later appeals . Many prominent groups and individuals , including singer Harry Belafonte , the NAACP and the European Parliament , are cited on his Web site as supporters . Prosecutors have insisted Abu-Jamal pay the ultimate price for his crime and have aggressively resisted efforts to take him off death row . `` This assassination has been made a circus by those people in the world and this city who believe falsely that Mumia Abu-Jamal is some kind of a folk hero , '' then-Philadelphia District Attorney Lynne Abraham said when the federal appeals court upheld the conviction . `` He is nothing short of an assassin . '' Abraham retired from her post this month .
Ex-Black Panther Mumia Abu-Jamal sentenced to death for killing Philadelphia police officer . He says there were procedural errors during his sentencing , too few blacks on the jury . Appeals court can now impose death sentence or order new trial to hear claims of injustice . `` He is nothing short of an assassin . '' former Philadelphia district attorney says .