Avery Cardinal Dulles, 2004

 “The reversal of a doctrine as well established as the legitimacy of capital punishment would raise serious problems regarding the credibility of the magisterium. Consistency with scripture and long-standing Catholic tradition is important for the grounding of many current teachings of the Catholic Church; for example, those regarding abortion, contraception, the permanence of marriage, and the ineligibility of women for priestly ordination. If the tradition on capital punishment had been reversed, serious questions would be raised regarding other doctrines."  ---  Avery Cardinal Dulles, “Catholic Teaching on the Death Penalty”, in Owens, Carlson & Elshtain, op. cit., p. 26. Religion and the Death Penalty: A Call for Reckoning

Catholicism & Capital Punishment --- First Things Magazine April, 2001

In the Old Testament the Mosaic Law specifies no less than thirty-six capital offenses calling for execution by stoning, burning, decapitation, or strangulation. Included in the list are idolatry, magic, blasphemy, violation of the sabbath, murder, adultery, bestiality, pederasty, and incest. The death penalty was considered especially fitting as a punishment for murder since in his covenant with Noah God had laid down the principle, "Whoever sheds the blood of man, by man shall his blood be shed, for God made man in His own image" (Genesis 9:6). In many cases God is portrayed as deservedly punishing culprits with death, as happened to Korah, Dathan, and Abiram (Numbers 16). In other cases individuals such as Daniel and Mordecai are God's agents in bringing a just death upon guilty persons.

In the New Testament the right of the State to put criminals to death seems to be taken for granted. Jesus himself refrains from using violence. He rebukes his disciples for wishing to call down fire from heaven to punish the Samaritans for their lack of hospitality (Luke 9:55). Later he admonishes Peter to put his sword in the scabbard rather than resist arrest (Matthew 26:52). At no point, however, does Jesus deny that the State has authority to exact capital punishment. In his debates with the Pharisees, Jesus cites with approval the apparently harsh commandment, "He who speaks evil of father or mother, let him surely die" (Matthew 15:4; Mark 7:10, referring to Exodus 2l:17; cf. Leviticus 20:9). When Pilate calls attention to his authority to crucify him, Jesus points out that Pilate's power comes to him from above — that is to say, from God (John 19:11). Jesus commends the good thief on the cross next to him, who has admitted that he and his fellow thief are receiving the due reward of their deeds (Luke 23:41).

The early Christians evidently had nothing against the death penalty. They approve of the divine punishment meted out to Ananias and Sapphira when they are rebuked by Peter for their fraudulent action (Acts 5:1-11). The Letter to the Hebrews makes an argument from the fact that "a man who has violated the law of Moses dies without mercy at the testimony of two or three witnesses" (10:28). Paul repeatedly refers to the connection between sin and death. He writes to the Romans, with an apparent reference to the death penalty, that the magistrate who holds authority "does not bear the sword in vain; for he is the servant of God to execute His wrath on the wrongdoer" (Romans 13:4). No passage in the New Testament disapproves of the death penalty.

Turning to Christian tradition, we may note that the Fathers and Doctors of the Church are virtually unanimous in their support for capital punishment, even though some of them such as St. Ambrose exhort members of the clergy not to pronounce capital sentences or serve as executioners. To answer the objection that the first commandment forbids killing, St. Augustine writes in The City of God:

   The same divine law which forbids the killing of a human being allows certain exceptions, as when God authorizes killing by a general law or when He gives an explicit commission to an individual for a limited time. Since the agent of authority is but a sword in the hand, and is not responsible for the killing, it is in no way contrary to the commandment, "Thou shalt not kill" to wage war at God's bidding, or for the representatives of the State's authority to put criminals to death, according to law or the rule of rational justice.

In the Middle Ages a number of canonists teach that ecclesiastical courts should refrain from the death penalty and that civil courts should impose it only for major crimes. But leading canonists and theologians assert the right of civil courts to pronounce the death penalty for very grave offenses such as murder and treason. Thomas Aquinas and Duns Scotus invoke the authority of Scripture and patristic tradition, and give arguments from reason.

Giving magisterial authority to the death penalty, Pope Innocent III required disciples of Peter Waldo seeking reconciliation with the Church to accept the proposition: "The secular power can, without mortal sin, exercise judgment of blood, provided that it punishes with justice, not out of hatred, with prudence, not precipitation." In the high Middle Ages and early modern times the Holy See authorized the Inquisition to turn over heretics to the secular arm for execution. In the Papal States the death penalty was imposed for a variety of offenses. The Roman Catechism, issued in 1566, three years after the end of the Council of Trent, taught that the power of life and death had been entrusted by God to civil authorities and that the use of this power, far from involving the crime of murder, is an act of paramount obedience to the fifth commandment.

In modern times Doctors of the Church such as Robert Bellarmine and Alphonsus Liguori held that certain criminals should be punished by death. Venerable authorities such as Francisco de Vitoria, Thomas More, and Francisco Suárez agreed. John Henry Newman, in a letter to a friend, maintained that the magistrate had the right to bear the sword, and that the Church should sanction its use, in the sense that Moses, Joshua, and Samuel used it against abominable crimes.

Throughout the first half of the twentieth century the consensus of Catholic theologians in favor of capital punishment in extreme cases remained solid, as may be seen from approved textbooks and encyclopedia articles of the day. The Vatican City State from 1929 until 1969 had a penal code that included the death penalty for anyone who might attempt to assassinate the pope. Pope Pius XII, in an important allocution to medical experts, declared that it was reserved to the public power to deprive the condemned of the benefit of life in expiation of their crimes.

Summarizing the verdict of Scripture and tradition, we can glean some settled points of doctrine. It is agreed that crime deserves punishment in this life and not only in the next. In addition, it is agreed that the State has authority to administer appropriate punishment to those judged guilty of crimes and that this punishment may, in serious cases, include the sentence of death.

Avery Cardinal Dulles, 2008 -  An unpublished interview with Avery Dulles   National Catholic Reporter by John L. Allen, Jr. -  Dec 19, 2008.
Allen asked Dulles to identify the most important forces shaping the future of the Catholic church.

"Restoring clarity where there had been confusion in the period following the Second Vatican Council," Dulles said. "Rebuilding a strong sense of Catholic identity, including a clear repudiation of the notion that church history can be divided into a 'before' and 'after' Vatican II. … Specifically, Dulles said, his hunch was that the church may ultimately return to a "more traditional posture" on both the death penalty and the idea of a "just war." Recent popes, Dulles conceded, beginning with John XXIIII, seem to have taken quasi-abolitionist positions on both matters. Yet used sparingly and with safeguards to protect the interests of justice, Dulles argued, both the death penalty and war have, over the centuries, been recognized by the church as legitimate, sometimes even obligatory, exercises of state power." 

Avery Cardinal Dulles, S.J. 1918 – 2008 was created a Cardinal of the Catholic Church in 2001 by Pope John Paul II, the first American-born theologian who is not a bishop to receive this honor. He is the past President of both the Catholic Theological Society of America and the American Theological Society and Professor Emeritus at The Catholic University of America. He has served on the International Theological Commission and as a consultant to the Committee on Doctrine of the National Conference of Catholic Bishops.