In light of Huckabee's clemency scandal, Radley Balko zooms out and considers the issue more generally:
The wisdom of a pardon or clemency granted because a particular verdict, sentence, or application of the law was unjust ought to be judged on precisely that, and only thatwhether the final outcome is consistent with our notion of justice. What happens later is irrelevant. On the other hand, when a governor pardons or frees on rehabilitation grounds someone who unquestionably committed the crime, he's made a bolder proclamation, and put his own judgment on the line. If you're going to pronounce a convicted murderer redeemed by letting him out of prison, you really should be on the hook for the killer's behavior for the rest of his life.