What Punishment Does Couey Not Deserve?

My hesitation regarding retribution as the impetus for state punishment stems from the absence of readily apparent limits. Rick offers that "punishment in excess of desert is impermissible, but also that punishment consistent with desert is permissible." As such, John Couey "may not be punished more severely than he deserves," but "it is possible for a responsible agent to deserve justly-structured punishment." I agree, but what sort of punishment does Couey not deserve? In my estimation, the "but I don't deserve this" defense is categorically unavailable to a man who kidnaps, sexually abuses, and murders a child. If retribution is equated with desert, it seems that the permissible scope of punishments is boundless. Rick wisely notes that Christian love supplies a reason for mercy, but in that case we seem to have left the province of desert. Iran's approach to punishment may be a failure of mercy, but how can it be considered a failure of desert? If mercy is to lead us to alleviate the awful and stark ramifications of desert, maybe an acceptable Christian justification for punishment is "retribution lite" (retribution tempered by mercy), for it can't be retribution as equated with desert, can it?

Rob