What is justice?

As many of you are probably aware of by now the case of Troy Davis is getting a lot of attention. I find this particularly interesting because of my undergrad in Forensic Science. I love reading about cases. This one is particularly interesting. Now in the interest of full disclosure if anyone is reading this, I am anti death penalty in ALL cases so that should be said. Having said the fact this case has gone this far is an embarrassment. I have a major problem with the Judge presiding over Troy's attempt to get a new case saying that the recantations of witnesses was unreliable but their initial (supposedly coerced) courtroom testimony was in fact reliable. I just can't see how this case has gone this far. The board of Parole spent the better part of the day hearing the testimony of both sides of the argument. While watching a story on the case they interviews the mother of Marc MacPhail the off duty officer killed in the case. She said she just wants justice for the death of her son. This stirred up all sorts of emotions within me. What is justice? Is justice accomplished by sending a man to death when there are serious questions about his guilt or innocence? The fact of the matter is unavoidable. While many people capital punishment kills are guilty invariably there are innocent people wrongly convicted who are executed in a guilty person's stead and it's there I find my comfort. I'm a Christian. It's not a secret or anything that I hide from people i'm pretty vocal about it. I find comfort when my heart hurts over the death of a potentially innocent person by thinking about the greatest example of love I have ever know. Christ died a criminals death in our stead to save us from our own suffering. Christ even says that there is "no greater love than a man lay down his life for a brother". John 15:13 It's things like this that bring me hope. I long for the day when my state and my country kills no one in my name for the sake of justice because I know that the law of averages catches up and eventually they kill an innocent man or woman. I also take solace that like the thief on the cross if someone cries out to God before they are executed that they too will be held in his arms. So the question returns.What is justice or more importantly is it our place or God's to dole out justice?