(The Gospel of Life)
Pope John Paul II, 1995
55. ... Moreover, "legitimate defense can be not only a right but a grave duty for someone responsible for another's life, the common good of the family or of the state."44 Unfortunately, it happens that the need to render the aggressor incapable of causing harm sometimes involves taking his life. In this case, the fatal outcome is attributable to the aggressor whose action brought it about, even though he may not be morally responsible because of a lack of the use of reason.45
56. This is the context in which to place the problem of the death penalty. On this matter there is a growing tendency, both in the church and in civil society, to demand that it be applied in a very limited way or even that it be abolished completely. The problem must be viewed in the context of a system of penal justice ever more in line with human dignity and thus, in the end, with God's plan for man and society. The primary purpose of the punishment which society inflicts is "to redress the disorder caused by the offense."46 Public authority must redress the violation of personal and social rights by imposing on the offender an adequate punishment for the crime, as a condition for the offender to regain the exercise of his or her freedom. In this way authority also fulfills the purpose of defending public order and ensuring people's safety, while at the same time offering the offender an incentive and help to change his or her behavior and be rehabilitated.47
It is clear that for these purposes to be achieved, the nature and extent of the punishment must be carefully evaluated and decided upon, and ought not go to the extreme of executing the offender except in cases of absolute necessity: In other words, when it would not be possible otherwise to defend society. Today however, as a result of steady improvements in the organization of the penal system, such cases are very rare if not practically nonexistent.
In any event, the principle set forth in the new Catechism of the Catholic Church remains valid: "If bloodless means are sufficient to defend human lives against an aggressor and to protect public order and the safety of persons, public authority must limit itself to such means, because they better correspond to the concrete conditions of the common good and are more in conformity to the dignity of the human person."48
44 Catechism of the Catholic Church, 2265. (Referring to 2266 prior to the modifications of September, 1997).
45 Cf. St. Thomas Aquinas, Summa Thelogiae, II-II, q. 64, a. 7; St. Alphonsus de Liguori, Theologia Moralis, 1, III,; tr. 4, c. 1, dub. 3.
46 Catechism of the Catholic Church, 2266.
47 Cf. Ibid.
48 No. 2267