I think it's clear that Mumia Abu-Jamal murdered Philadelphia cop Daniel Faulkner. If he had been executed for that crime, it wouldn't have been an injustice. But it was wrong and unprincipled of the Senate to reject the president's nomination of Debo Adegbile to head the Justice Department's Civil Rights division just because he once worked on an NCAACP legal team that filed a brief---a successful brief, at that---on Mumia's behalf. This decision will make it less likely that young lawyers will take on controversial cases early in their careers. Besides, as has been pointed out, Chief Justice Roberts once did some pro bono work for a serial killer who was eventually executed.
Maybe Roberts will speak out and rebuke the Senate in defense of the important principle that everyone, no matter how unpopular, is entitled to adequate legal representation in court? Don't hold your breath.