You shall not kill.Ex 20:13; cf. Deut 5:17.

“You have heard that it was said to the men of old, ‘You shall not kill: and whoever kills shall be liable to judgment.’ But I say to you that every one who is angry with his brother shall be liable to judgment.’”Mt 5:21-22.

2258“Human life is sacred because from its beginning it involves the creative action of God and it remains for ever in a special relationship with the Creator, who is its sole end. God alone is the Lord of life from its beginning until its end: no one can under any circumstance claim for himself the right directly to destroy an innocent human being.”Congregation for the Doctrine of the Faith, instruction Donum vitae intro. 5.

The Witness of Sacred History

2259In the account of Abel’s murder by his brother Cain,Cf. Gen 4:8-12. Scripture reveals the presence of anger and envy in man, consequences of original sin, from the beginning of human history. Man has become the enemy of his fellow man. God declares the wickedness of this fratricide: “What have you done? The voice of your brother’s blood is crying to me from the ground. And now you are cursed from the ground, which has opened its mouth to receive your brother’s blood from your hand.”Gen 4:10-11.

2260The covenant between God and mankind is interwoven with reminders of God’s gift of human life and man’s murderous violence:

For your lifeblood I will surely require a reckoning. . . . Whoever sheds the blood of man, by man shall his blood be shed; for God made man in his own image.Gen 9:5-6.

The Old Testament always considered blood a sacred sign of life.Cf. Lev 17:14. This teaching remains necessary for all time.

2261Scripture specifies the prohibition contained in the fifth commandment: “Do not slay the innocent and the righteous.”Ex 23:7. The deliberate murder of an innocent person is gravely contrary to the dignity of the human being, to the golden rule, and to the holiness of the Creator. The law forbidding it is universally valid: it obliges each and everyone, always and everywhere.

2262In the Sermon on the Mount, the Lord recalls the commandment, “You shall not kill,”Mt 5:21. and adds to it the proscription of anger, hatred, and vengeance. Going further, Christ asks his disciples to turn the other cheek and to love their enemies.Cf. Mt 5:22-44. He did not defend himself and told Peter to leave his sword in its sheath.Cf. Mt 26:52.

Legitimate Defense

2263The legitimate defense of persons and societies is not an exception to the prohibition against the murder of the innocent that constitutes intentional killing. “The act of self-defense can have a double effect: the preservation of one’s own life; and the killing of the aggressor. . . . The one is intended, the other is not.”St. Thomas Aquinas, Summa theologiae II-II,64,7.

2264Love toward oneself remains a fundamental principle of morality. Therefore it is legitimate to insist on respect for one’s own right to life. Someone who defends his life is not guilty of murder even if he is forced to deliver his aggressor a lethal blow:

If a man in self-defense uses more than necessary violence, it will be unlawful: whereas if he repels force with moderation, his defense will be lawful. . . . Nor is it necessary for salvation that a man omit the act of moderate self-defense to avoid killing the other man, since one is bound to take more care of one’s own life than of another’s.St. Thomas Aquinas, Summa theologiae II-II,64,7 ad 3.

2265Legitimate defense can be not only a right but a grave duty for one who is responsible for the lives of others. The defense of the common good requires that an unjust aggressor be rendered unable to cause harm. For this reason those who legitimately hold authority also have the right to use arms to repel aggressors against the civil community entrusted to their responsibility.

2266The efforts of the state to curb the spread of behavior harmful to people’s rights and to the basic rules of civil society correspond to the requirement of safeguarding the common good. Legitimate public authority has the right and duty to inflict punishment proportionate to the gravity of the offense. Punishment has the primary aim of redressing the disorder introduced by the offense. When it is willingly accepted by the guilty party, it assumes the value of expiation. Punishment then, in addition to defending public order and protecting people’s safety, has a medicinal purpose: as far as possible, it must contribute to the correction of the guilty party.Cf. Lk 23:40-43.

Recourse to the death penalty on the part of legitimate authority, following a fair trial, was long considered an appropriate response to the gravity of certain crimes and an acceptable, albeit extreme, means of safeguarding the common good.

Today, however, there is an increasing awareness that the dignity of the person is not lost even after the commission of very serious crimes. In addition, a new understanding has emerged of the significance of penal sanctions imposed by the state. Lastly, more effective systems of detention have been developed, which ensure the due protection of citizens but, at the same time, do not definitively deprive the guilty of the possibility of redemption.

2267Consequently, the Church teaches, in the light of the Gospel, that “the death penalty is inadmissible because it is an attack on the inviolability and dignity of the person,”Francis, Address, 11 October 2017; cf. Congregation for the Doctrine of the Faith, Letter to the Bishops Regarding the New Revision of Number 2267 of the Catechism of the Catholic Church (1 August 2018). and she works with determination for its abolition worldwide.

Intentional Homicide

2268The fifth commandment forbids direct and intentional killing as gravely sinful. The murderer and those who cooperate voluntarily in murder commit a sin that cries out to heaven for vengeance.Cf. Gen 4:10. Infanticide,Cf. GS 51 § 3. fratricide, parricide, and the murder of a spouse are especially grave crimes by reason of the natural bonds which they break. Concern for eugenics or public health cannot justify any murder, even if commanded by public authority.

2269The fifth commandment forbids doing anything with the intention of indirectly bringing about a person’s death. The moral law prohibits exposing someone to mortal danger without grave reason, as well as refusing assistance to a person in danger. The acceptance by human society of murderous famines, without efforts to remedy them, is a scandalous injustice and a grave offense. Those whose usurious and avaricious dealings lead to the hunger and death of their brethren in the human family indirectly commit homicide, which is imputable to them.Cf. Am 8:4-10. Unintentional killing is not morally imputable. But one is not exonerated from grave offense if, without proportionate reasons, he has acted in a way that brings about someone’s death, even without the intention to do so.

Abortion

2270Human life must be respected and protected absolutely from the moment of conception. From the first moment of his existence, a human being must be recognized as having the rights of a person - among which is the inviolable right of every innocent being to life.Cf. Congregation for the Doctrine of the Faith, Donum vitae I,1.

“Before I formed you in the womb I knew you, and before you were born I consecrated you.”Jer 1:5; cf. Job 10:8-12; Ps 22:10-11.

“My frame was not hidden from you, when I was being made in secret, intricately wrought in the depths of the earth.”Ps 139:15.

2271Since the first century the Church has affirmed the moral evil of every procured abortion. This teaching has not changed and remains unchangeable. Direct abortion, that is to say, abortion willed either as an end or a means, is gravely contrary to the moral law:

“You shall not kill the embryo by abortion and shall not cause the newborn to perish.”Didache 2,2: SCh 248,148; cf. Epistle of Barnabas 19,5: PG 2,777; Ad Diognetum 5,6: PG 2,1173; Tertullian, Apology 9: PL 1,319-320.

“God, the Lord of life, has entrusted to men the noble mission of safeguarding life, and men must carry it out in a manner worthy of themselves. Life must be protected with the utmost care from the moment of conception: abortion and infanticide are abominable crimes.”GS 51 § 3.

2272Formal cooperation in an abortion constitutes a grave offense. The Church attaches the canonical penalty of excommunication to this crime against human life. “A person who procures a completed abortion incurs excommunication latae sententiae,”CIC, can. 1398. “by the very commission of the offense,”CIC, can. 1314. and subject to the conditions provided by Canon Law.Cf. CIC, cann. 1323-1324. The Church does not thereby intend to restrict the scope of mercy. Rather, she makes clear the gravity of the crime committed, the irreparable harm done to the innocent who is put to death, as well as to the parents and the whole of society.

2273The inalienable right to life of every innocent human individual is a constitutive element of civil society and its legislation:

“The inalienable rights of the person must be recognized and respected by civil society and the political authority. These human rights depend neither on single individuals nor on parents; nor do they represent a concession made by society and the state; they belong to human nature and are inherent in the person by virtue of the creative act from which the person took his origin. Among such fundamental rights one should mention in this regard every human being’s right to life and physical integrity from the moment of conception until death.”CDF, Donum vitae III.

“The moment a positive law deprives a category of human beings of the protection which civil legislation ought to accord them, the state is denying the equality of all before the law. When the state does not place its power at the service of the rights of each citizen, and in particular of the more vulnerable, the very foundations of a state based on law are undermined. . . . As a consequence of the respect and protection which must be ensured for the unborn child from the moment of conception, the law must provide appropriate penal sanctions for every deliberate violation of the child’s rights.”CDF, Donum vitae III.

2274Since it must be treated from conception as a person, the embryo must be defended in its integrity, cared for, and healed, as far as possible, like any other human being.

Prenatal diagnosis is morally licit, “if it respects the life and integrity of the embryo and the human fetus and is directed toward its safeguarding or healing as an individual. . . . It is gravely opposed to the moral law when this is done with the thought of possibly inducing an abortion, depending upon the results: a diagnosis must not be the equivalent of a death sentence.”CDF, Donum vitae I,2.

“One must hold as licit procedures carried out on the human embryo which respect the life and integrity of the embryo and do not involve disproportionate risks for it, but are directed toward its healing the improvement of its condition of health, or its individual survival.”CDF, Donum vitae I,3.

“It is immoral to produce human embryos intended for exploitation as disposable biological material.”CDF, Donum vitae I,5.

2275“Certain attempts to influence chromosomic or genetic inheritance are not therapeutic but are aimed at producing human beings selected according to sex or other predetermined qualities. Such manipulations are contrary to the personal dignity of the human being and his integrity and identity”CDF, Donum vitae I,6. which are unique and unrepeatable.

Euthanasia

2276Those whose lives are diminished or weakened deserve special respect. Sick or handicapped persons should be helped to lead lives as normal as possible.

2277Whatever its motives and means, direct euthanasia consists in putting an end to the lives of handicapped, sick, or dying persons. It is morally unacceptable. Thus an act or omission which, of itself or by intention, causes death in order to eliminate suffering constitutes a murder gravely contrary to the dignity of the human person and to the respect due to the living God, his Creator. The error of judgment into which one can fall in good faith does not change the nature of this murderous act, which must always be forbidden and excluded.

2278Discontinuing medical procedures that are burdensome, dangerous, extraordinary, or disproportionate to the expected outcome can be legitimate; it is the refusal of “over-zealous” treatment. Here one does not will to cause death; one’s inability to impede it is merely accepted. The decisions should be made by the patient if he is competent and able or, if not, by those legally entitled to act for the patient, whose reasonable will and legitimate interests must always be respected.

2279Even if death is thought imminent, the ordinary care owed to a sick person cannot be legitimately interrupted. The use of painkillers to alleviate the sufferings of the dying, even at the risk of shortening their days, can be morally in conformity with human dignity if death is not willed as either an end or a means, but only foreseen and tolerated as inevitable. Palliative care is a special form of disinterested charity. As such it should be encouraged.

Suicide

2280Everyone is responsible for his life before God who has given it to him. It is God who remains the sovereign Master of life. We are obliged to accept life gratefully and preserve it for his honor and the salvation of our souls. We are stewards, not owners, of the life God has entrusted to us. It is not ours to dispose of.

2281Suicide contradicts the natural inclination of the human being to preserve and perpetuate his life. It is gravely contrary to the just love of self. It likewise offends love of neighbor because it unjustly breaks the ties of solidarity with family, nation, and other human societies to which we continue to have obligations. Suicide is contrary to love for the living God.

2282If suicide is committed with the intention of setting an example, especially to the young, it also takes on the gravity of scandal. Voluntary cooperation in suicide is contrary to the moral law. Grave psychological disturbances, anguish, or grave fear of hardship, suffering, or torture can diminish the responsibility of the one committing suicide.

2283We should not despair of the eternal salvation of persons who have taken their own lives. By ways known to him alone, God can provide the opportunity for salutary repentance. The Church prays for persons who have taken their own lives.

Respect for the Souls of Others: Scandal

2284Scandal is an attitude or behavior which leads another to do evil. The person who gives scandal becomes his neighbor’s tempter. He damages virtue and integrity; he may even draw his brother into spiritual death. Scandal is a grave offense if by deed or omission another is deliberately led into a grave offense.

2285Scandal takes on a particular gravity by reason of the authority of those who cause it or the weakness of those who are scandalized. It prompted our Lord to utter this curse: “Whoever causes one of these little ones who believe in me to sin, it would be better for him to have a great millstone fastened round his neck and to be drowned in the depth of the sea.”Mt 18:6; cf. 1 Cor 8:10-13. Scandal is grave when given by those who by nature or office are obliged to teach and educate others. Jesus reproaches the scribes and Pharisees on this account: he likens them to wolves in sheep’s clothing.Cf. Mt 7:15.

2286Scandal can be provoked by laws or institutions, by fashion or opinion. Therefore, they are guilty of scandal who establish laws or social structures leading to the decline of morals and the corruption of religious practice, or to “social conditions that, intentionally or not, make Christian conduct and obedience to the Commandments difficult and practically impossible.”Pius XII, Discourse, 1 June 1941. This is also true of business leaders who make rules encouraging fraud, teachers who “provoke their children to anger,”Cf. Eph 6:4; Col 3:21. or anyone who manipulates public opinion to obtain sinful practices.
Anyone who uses the power at his disposal in such a way that it leads others to do wrong becomes guilty of scandal and responsible for the evil that he has directly or indirectly encouraged. “Temptations to sin are sure to come; but woe to him by whom they come!”Lk 17:1.

Respect for Health

2288Life and physical health are precious gifts entrusted to us by God. We must take reasonable care of them, taking into account the needs of others and the common good. Concern for the health of its citizens requires that society help in the attainment of living conditions that allow them to grow and reach maturity: food and clothing, housing, health care, basic education, employment, and social assistance.

2289If morality requires respect for the life of the body, it does not make it an absolute value. It rejects a neo-pagan notion that tends to promote the cult of the body, to sacrifice everything for its sake, to idolize physical perfection and success at sports. By its selective preference of the strong over the weak, such a conception can lead to the perversion of human relationships.

2290The virtue of temperance disposes us to avoid every kind of excess: the abuse of food, alcohol, tobacco, or medicine. Those incur grave guilt who, by drunkenness or a love of speed, endanger their own and others’ safety on the road, at sea, or in the air.

2291The use of drugs inflicts very grave damage on human health and life. Their use, except on strictly therapeutic grounds, is a grave offense. Clandestine production of and trafficking in drugs are scandalous practices. They constitute direct cooperation in evil, since they encourage people to practices gravely contrary to the moral law.

Respect for the Person and Scientific Research

2292Scientific, medical, or psychological experiments on human individuals or groups can contribute to healing the sick and the advancement of public health.

2293Basic scientific research, as well as applied research, is a significant expression of man’s dominion over creation. Science and technology are precious resources when placed at the service of man and promote his integral development for the benefit of all. By themselves however they cannot disclose the meaning of existence and of human progress. Science and technology are ordered to man, from whom they take their origin and development; hence they find in the person and in his moral values both evidence of their purpose and awareness of their limits.

2294It is an illusion to claim moral neutrality in scientific research and its applications. On the other hand, guiding principles cannot be inferred from simple technical efficiency, or from the usefulness accruing to some at the expense of others or, even worse, from prevailing ideologies. Science and technology by their very nature require unconditional respect for fundamental moral criteria. They must be at the service of the human person, of his inalienable rights, of his true and integral good, in conformity with the plan and the will of God.

2295Research or experimentation on the human being cannot legitimate acts that are in themselves contrary to the dignity of persons and to the moral law. The subjects’ potential consent does not justify such acts. Experimentation on human beings is not morally legitimate if it exposes the subject’s life or physical and psychological integrity to disproportionate or avoidable risks. Experimentation on human beings does not conform to the dignity of the person if it takes place without the informed consent of the subject or those who legitimately speak for him.

2296Organ transplants are in conformity with the moral law if the physical and psychological dangers and risks to the donor are proportionate to the good sought for the recipient. Organ donation after death is a noble and meritorious act and is to be encouraged as an expression of generous solidarity. It is not morally acceptable if the donor or his proxy has not given explicit consent. Moreover, it is not morally admissible to bring about the disabling mutilation or death of a human being, even in order to delay the death of other persons.

Respect for Bodily Integrity

2297Kidnapping and hostage taking bring on a reign of terror; by means of threats they subject their victims to intolerable pressures. They are morally wrong. Terrorism threatens, wounds, and kills indiscriminately; it is gravely against justice and charity. Torture which uses physical or moral violence to extract confessions, punish the guilty, frighten opponents, or satisfy hatred is contrary to respect for the person and for human dignity. Except when performed for strictly therapeutic medical reasons, directly intended amputations, mutilations, and sterilizations performed on innocent persons are against the moral law.Cf. DS 3722.

2298In times past, cruel practices were commonly used by legitimate governments to maintain law and order, often without protest from the pastors of the Church, who themselves adopted in their own tribunals the prescriptions of Roman law concerning torture. Regrettable as these facts are, the Church always taught the duty of clemency and mercy. She forbade clerics to shed blood. In recent times it has become evident that these cruel practices were neither necessary for public order nor in conformity with the legitimate rights of the human person. On the contrary, these practices led to ones even more degrading. It is necessary to work for their abolition. We must pray for the victims and their tormentors.

Respect for the Dead

2299The dying should be given attention and care to help them live their last moments in dignity and peace. They will be helped by the prayer of their relatives, who must see to it that the sick receive at the proper time the sacraments that prepare them to meet the living God.

2300The bodies of the dead must be treated with respect and charity, in faith and hope of the Resurrection. The burial of the dead is a corporal work of mercy;Cf. Tob 1:16-18. it honors the children of God, who are temples of the Holy Spirit.

2301Autopsies can be morally permitted for legal inquests or scientific research. The free gift of organs after death is legitimate and can be meritorious. The Church permits cremation, provided that it does not demonstrate a denial of faith in the resurrection of the body.CIC, can. 1176 § 3.

Peace

2302By recalling the commandment, “You shall not kill,”Mt 5:21. our Lord asked for peace of heart and denounced murderous anger and hatred as immoral.

Anger is a desire for revenge. “To desire vengeance in order to do evil to someone who should be punished is illicit,” but it is praiseworthy to impose restitution “to correct vices and maintain justice.”St. Thomas Aquinas, Summa theologiae II-II,158,1 ad 3. If anger reaches the point of a deliberate desire to kill or seriously wound a neighbor, it is gravely against charity; it is a mortal sin. The Lord says, “Everyone who is angry with his brother shall be liable to judgment.”Mt 5:22.

2303Deliberate hatred is contrary to charity. Hatred of the neighbor is a sin when one deliberately wishes him evil. Hatred of the neighbor is a grave sin when one deliberately desires him grave harm. “But I say to you, Love your enemies and pray for those who persecute you, so that you may be sons of your Father who is in heaven.”Mt 5:44-45.

2304Respect for and development of human life require peace. Peace is not merely the absence of war, and it is not limited to maintaining a balance of powers between adversaries. Peace cannot be attained on earth without safeguarding the goods of persons, free communication among men, respect for the dignity of persons and peoples, and the assiduous practice of fraternity. Peace is “the tranquillity of order.”St. Augustine, De civitate Dei 19,13,1: PL 41,640. Peace is the work of justice and the effect of charity.Cf. Isa 32:17; GS 78 §§ 1-2.

2305Earthly peace is the image and fruit of the peace of Christ, the messianic “Prince of Peace.”Isa 9:5. By the blood of his Cross, “in his own person he killed the hostility,”Eph 2:16 (J.B.); cf. Col 1:20-22. he reconciled men with God and made his Church the sacrament of the unity of the human race and of its union with God. “He is our peace.”Eph 2:14. He has declared: “Blessed are the peacemakers.”Mt 5:9.

2306Those who renounce violence and bloodshed and, in order to safeguard human rights, make use of those means of defense available to the weakest, bear witness to evangelical charity, provided they do so without harming the rights and obligations of other men and societies. They bear legitimate witness to the gravity of the physical and moral risks of recourse to violence, with all its destruction and death.Cf. GS 78 § 5.

Avoiding War

2307The fifth commandment forbids the intentional destruction of human life. Because of the evils and injustices that accompany all war, the Church insistently urges everyone to prayer and to action so that the divine Goodness may free us from the ancient bondage of war.Cf. GS 81 § 4.

2308All citizens and all governments are obliged to work for the avoidance of war. However, “as long as the danger of war persists and there is no international authority with the necessary competence and power, governments cannot be denied the right of lawful self-defense, once all peace efforts have failed.”GS 79 § 4.

2309The strict conditions for legitimate defense by military force require rigorous consideration. The gravity of such a decision makes it subject to rigorous conditions of moral legitimacy. At one and the same time:

• the damage inflicted by the aggressor on the nation or community of nations must be lasting, grave, and certain;
• all other means of putting an end to it must have been shown to be impractical or ineffective;
• there must be serious prospects of success;
• the use of arms must not produce evils and disorders graver than the evil to be eliminated. The power of modern means of destruction weighs very heavily in evaluating this condition.

These are the traditional elements enumerated in what is called the “just war” doctrine. The evaluation of these conditions for moral legitimacy belongs to the prudential judgment of those who have responsibility for the common good.

2310Public authorities, in this case, have the right and duty to impose on citizens the obligations necessary for national defense. Those who are sworn to serve their country in the armed forces are servants of the security and freedom of nations. If they carry out their duty honorably, they truly contribute to the common good of the nation and the maintenance of peace.Cf. GS 79 § 5.

2311Public authorities should make equitable provision for those who for reasons of conscience refuse to bear arms; these are nonetheless obliged to serve the human community in some other way.Cf. GS 79 § 3.

2312The Church and human reason both assert the permanent validity of the moral law during armed conflict. “The mere fact that war has regrettably broken out does not mean that everything becomes licit between the warring parties.”GS 79 § 4.

2313Non-combatants, wounded soldiers, and prisoners must be respected and treated humanely. Actions deliberately contrary to the law of nations and to its universal principles are crimes, as are the orders that command such actions. Blind obedience does not suffice to excuse those who carry them out. Thus the extermination of a people, nation, or ethnic minority must be condemned as a mortal sin. One is morally bound to resist orders that command genocide.

2314“Every act of war directed to the indiscriminate destruction of whole cities or vast areas with their inhabitants is a crime against God and man, which merits firm and unequivocal condemnation.”GS 80 § 3. A danger of modern warfare is that it provides the opportunity to those who possess modern scientific weapons - especially atomic, biological, or chemical weapons - to commit such crimes.

2315The accumulation of arms strikes many as a paradoxically suitable way of deterring potential adversaries from war. They see it as the most effective means of ensuring peace among nations. This method of deterrence gives rise to strong moral reservations. The arms race does not ensure peace. Far from eliminating the causes of war, it risks aggravating them. Spending enormous sums to produce ever new types of weapons impedes efforts to aid needy populations;Cf. Paul VI, Populorum progressio 53. it thwarts the development of peoples. Over-armament multiplies reasons for conflict and increases the danger of escalation.

2316The production and the sale of arms affect the common good of nations and of the international community. Hence public authorities have the right and duty to regulate them. The short-term pursuit of private or collective interests cannot legitimate undertakings that promote violence and conflict among nations and compromise the international juridical order.

2317Injustice, excessive economic or social inequalities, envy, distrust, and pride raging among men and nations constantly threaten peace and cause wars. Everything done to overcome these disorders contributes to building up peace and avoiding war:

Insofar as men are sinners, the threat of war hangs over them and will so continue until Christ comes again; but insofar as they can vanquish sin by coming together in charity, violence itself will be vanquished and these words will be fulfilled: “they shall beat their swords into plowshares, and their spears into pruning hooks; nation shall not lift up sword against nation, neither shall they learn war any more.”GS 78 § 6; cf. Isa 2:4.