If you've ever spent any time on a college campus, chances are you've encountered a group of maybe-students with makeshift signs and ink-smeared pamphlets urging that you "Free Mumia." And if you bothered to grab a pamphlet or engage one of these activists, you would have discovered that "Mumia" is Mumia Abu-Jamal, who was convicted of the fairly brutal 1981 shooting death of 25-year-old Philadelphia police officer Daniel Faulkner. Abu-Jamal has always claimed that he is innocent, and in the nearly thirty years since his conviction, his banner has been taken up by an array of frequent bedfellows: assorted civil rights groups, low-wattage celebrities, slices of the international community and college kids.

Although proving Abu-Jamal's innocence remains the ultimate aim, the goals of the "Free Mumia" crowd have gradually become more modest. When a federal court threw out Abu-Jamal's death sentence in 2001 and an appeals court affirmed that decision in 2008, it was a huge victory for Abu-Jamal, and it looked as though Abu-Jamal would live out the remainder of his natural life in relative discomfort among other inmates of the Pennsylvania state prison system.

But the victory appears to have been fleeting. The Supreme Court recently ordered the appeals court to reconsider its ruling, with the possible result that Abu-Jamal's death sentence will be reinstated and his Magic School Bus tour through the state and federal judicial systems finally brought to an end.

A reporter and part-time cab driver (and the president of the Philadelphia Association of Black Journalists), what we know as the Abu-Jamal story began on December 9, 1981 at approximately four in the morning. Faulkner, on duty, pulled over a car driven by Abu-Jamal's brother, William Cook. Faulkner called for backup. Cook exited his vehicle. Faulkner did the same. A tussle ensued.

Abu-Jamal saw the dustup from across the street and ran toward the grappling duo. According to two people, Abu-Jamal pulled out a gun and shot Faulkner in the back. Faulkner, falling, returned fire and shot Abu-Jamal in the chest. Standing over the bloodied officer, Abu-Jamal fired his gun four more times, hitting the victim, among other places, squarely between the eyes.

Ballistics tests confirmed that the bullet that shot Abu-Jamal came from Faulkner's gun. Police on the scene found a pistol, registered to Abu-Jamal, with five spent shell casings. (Various ballistics records have become a matter of dispute.) A nurse and a police officer at the hospital where Abu-Jamal was taken reported that Abu-Jamal boasted, "I shot the motherfucker, and I hope the motherfucker dies." (This testimony was later disputed by the nurse's brother.) The officer said that he retorted, "If he dies, you die."

For a while, this seemed to be the way things were going. Faulkner did, indeed, die, and a jury of ten whites and two African-Americans convicted Abu-Jamal of his murder. The case moved to the penalty phase, which generally has three steps. First, the prosecutor says that the defendant is irredeemably evil (e.g., he killed a cop), and the defendant says that he is simply a product of his environment, or really not such a bad guy after all (e.g., he came from an abusive home, he has a negligible criminal record). Second, each juror weighs the former considerations ("aggravating factors") against the latter ("mitigating factors"), with each juror regarding or disregarding any mitigating factors as he or she sees fit. And third, the defendant is sentenced to die if (and only if) all the jurors agree that the aggravating factors outweigh the mitigating factors.

In Abu-Jamal's case, the jury deliberated for a few hours before finding that Abu-Jamal should be executed.

This was only the beginning. Abu-Jamal appealed, maintaining his innocence and claiming that his trial was flawed in just about every way imaginable: the judge was biased, his attorney (appointed against Abu-Jamal's will) was incompetent, the prosecutors were racist, the witnesses who testified against him were liars, the witnesses who would have testified in his favor were improperly disallowed. Over the next two decades, every state and federal court that examined these claims rejected them.

Finally, in 2001, Abu-Jamal caught a break. A federal trial court judge upheld Abu-Jamal's conviction but found that the sentencing phase in his trial was constitutionally flawed. To understand what the problem was, recall that in the sentencing phase, each juror is free to consider any mitigating factors that he or she finds relevant. I can, for example, weigh a defendant's civic contributions even if you don't find that fact persuasive, and you're free to consider factors that leave me unmoved.

The sentencing form in the Abu-Jamal case, according to the federal court, suggested an altogether different rule: that a juror could consider only those mitigating factors that all 12 jurors agreed were relevant. If a juror misunderstood the form in this way, he might have eliminated from his calculus a particular mitigating factor, even if he found that factor persuasive. And what if that mitigating factor, thrown on the scales, would have tipped the juror's vote in favor of life? Applying Supreme Court precedent, the judge held that this risk required him to throw out Abu-Jamal's death sentence.

After the Third Circuit Court of Appeals affirmed [PDF] this decision in 2008, things looked pretty rosy for Abu-Jamal. Until a few weeks ago, that is, when the Supreme Court handed down a unanimous opinion [PDF] in Smith v. Spisak, which found that there was nothing wrong, constitutionally speaking, with a sentencing form that was nearly identical to the one in Abu-Jamal's case.

One week later, the Supreme Court voided the Third Circuit opinion and ordered the appeals court to reconsider the Abu-Jamal holding in light of Spisak.

This is very bad news for Abu-Jamal. Given the similarity of the sentencing forms in his case and in Spisak, the almost inescapable conclusion is that if the Spisak form was acceptable, the one in his case was as well. If that's correct, then the Third Circuit will likely reverse the federal trial court and it may, as well, reinstate Abu-Jamal's death sentence.

So the 29-year-long Abu-Jamal story might be somewhere in the vicinity of its end. The incarceration of an innocent person is an all-too-common judicial tragedy, and any railroading of defendants by a racist criminal justice system intolerable. Abu-Jamal was lucky enough to appeal his case when the severe racial problems of Philadelphia's criminal justice system were being exposed, and his supporters were smart to portray his appeal as partly about a man, but also about a movement. This might make him a good cultural flashpoint, but given the strong lack of evidence for his innocence, it leaves him as an awkward standard-bearer for the aggrieved and the oppressed.

Ian Retford is the pseudonym of a lawyer in New York City.