Capitol Punihsment in America-Who can throw the first stone?

Religious people seem to always support capitol punishment because they say it is ordained in holy scripture. We are asking this evening, how this view compares to Jesus saying in the New Testament, "Let him who is without sin cast the first stone." Was Jesus saying that only a righteous and just society can utilize capitol punishment? Or did he abrogate the Old Testament laws on capitol punishment, saying that since none of us are without sin, capitol punishment is prohibited? We will have two religious scholars, pro-and con to guide us through this discussion.