Dissent? Abu Jamal shot Faulkner some 5 times as I recall.
Abu-Jamal was convicted by a kangaroo court in front of a notorious hanging judge who (according to a sworn affidavit by one of his own stenographers) said, "I'm gonna help them fry the nigger." The lead prosecutor later became infamous for issuing guidelines for jury selection that included overt racial discrimination. Abu-Jamal was denied his right to choose an attorney to represent him, instead being assigned one by the court over his objection, and he was denied his right to defend himself in court by being bound and gagged. Witnesses against him were in trouble with the legal system and subject to police/prosecution pressure, and several have recanted their testimony, claiming coercion. Abu-Jamal's gun was not checked, nor were his hands checked, for evidence of having recently fired a gun; and although Abu-Jamal was found with a .38 caliber and, allegedly, 5 spent shell casings, it was a .44 caliber bullet that was removed from Faulkner's body. Attempted re-enactments of the crime scene have shown that the alleged shots that missed Faulkner should've left marks on the sidewalk that were not visible in photographs of the crime scene. Witnesses have testified under oath that they told police that they saw another man shoot Faulkner, and had the police tear up the transcript of the conversation and pressure the witnesses to sign a different statement. This potentially exculpatory evidence was not made available to the defense team in Abu-Jamal's trial. The prosecutor was allowed to ask the defense witness whether she also supported other Blacks who killed police, and the defense's objection that this was prejudicial was overruled by the judge. Another man told police he killed Faulkner and passed a lie detector test, yet Abu-Jamal was not allowed to use this in court because his (court-assigned) defense team had decided to reject it. The prosecutor read at length from Abu-Jamal's on-air political statements in order to portray him as a radical.
Even if everything the prosecution says was true (and if it was, why didn't he get a real trial?), after Faulkner attacked him with deadly force, he had as much right to respond with deadly force in his own self-defense as George Zimmerman did after Trayvon Martin allegedly used deadly force in a conflict Zimmerman initiated.
Bottom line: Mumia Abu-Jamal was ambushed, framed, and put on trial for being a former Black Panther, radical radio show host; and murder was the crime they decided to convict him of.