Such moral reasoning forms part of the patrimony of human civilization. The adage "Let the punishment fit the crime" echoes the Old Testament injunction "An eye for an eye, a tooth for a tooth." The actual expression used by Scripture is still more explicit: "Anyone who maims another shall suffer the same injury in return: fracture for fracture, eye for eye, tooth for tooth; the injury inflicted is the injury to be suffered" (Leviticus 24:19-20)  As a principle of justice, and taken by itself, this logic seems to make perfect sense.
Yet such reasoning gives rise to several problems. First, do we really seek absolute justice? Would we like to see all crimes, sins and offenses (what about our own sins of abortion and the contraceptive killings of fertilized eggs) punished as they truly deserve?
In a typical passage from Scripture, the Psalmist, reflecting on the universality of guilt and consequent universal need for pardon, writes, "If you, O Lord, should mark our guilt, Lord, who would survive?" (Psalms 130). Who, indeed, we may ask, is free from moral evil? Who among us deserves no punishment?
Similar reflections have been capsulized in the First Eucharistic Prayer of the Catholic Mass, "Do not consider what we truly deserve, but grant us your forgiveness." In these words of the Roman Canon, we entreat our Lord not only to refrain from applying the punishment we truly deserve but even from considering it.
As we acknowledge in the preceding line of the canon, we are indeed sinners, and therefore worthy of punishment. Clearly this argument in and of itself would not rule out the death penalty, but as Christians it should give us pause when we seek to exact full retribution for others' sins.
On the one hand we recognize that legitimate public authority has the right and duty to inflict penalties commensurate with the gravity of the crime. The moral sense of mankind has always insisted that good actions merit praise and reward, while evil deserves reprobation and punishment. It likewise offends our sense of justice to think all crimes should receive equal punishment or that greater offenses should not receive correspondingly greater penalties.
On the other hand, we shun certain punishments as unworthy of a truly human society. In so doing we implicitly invoke another standard to temper the principle of justice: the principle of respect for human dignity. Thus Pope John Paul II insists public authority should limit itself to bloodless means whenever possible since they "are more in conformity to the dignity of the human person."
The Second Vatican Council noted the "growing awareness of the exalted dignity proper to the human person," together with his universal rights and duties. The question of the dignity of the person and the unborn person commands supreme importance, because from this dignity spring man's natural rights, the most basic of which is the inalienable right to life.
Does this dignity, and hence this right, perdure in the criminal, or does he somehow forfeit his dignity? Does one's crime effectively alienate the inalienable right to life?
In my opinion, personal sinfulness does not abrogate the sanctity of the life of the sinner nor his dignity as a person. In his encyclical Evangelium Vitae, Pope John Paul speaks of the "great care that must be taken to respect every life, even that of criminals and unjust aggressors." Likewise, when in recent years the pope has issued appeals for clemency in the cases of Karla Faye Tucker and Joseph O'Dell, he has made no reference to the verdict of the court or of the possible innocence of the plaintiffs. Rather he has appealed to the sanctity of all human life, which belongs to God and not to man.
In 1960, long before becoming pope, Karol Wojtyla expressed what he called the "personalist principle," which states that "the person is a good towards which the only proper and adequate attitude is love."