The Church has observed war for two thousand years. She has studied it, argued over it, and worked it out as a doctrine.

That doctrine holds that war is a grave evil, that it is sometimes a duty, and that in either case it stands under the same moral law as every other human act. Most Catholics have never heard that law set out. Just War Doctrine sets it out in full.

The book is a complete statement of the classical teaching, built the way the old manuals were built: short numbered articles, objections raised and answered, conclusions stated plainly. It runs from St. Augustine and St. Thomas Aquinas through Cajetan, Vitoria, Suárez and Bellarmine to McHugh and Callan, and reads the whole tradition in the light of the Roman Catechism, Pius XII, the Second Vatican Council and the Catechism of the Catholic Church. It covers:

• The nature of war and of authority: who may make war, and why a private man or a faction may not
• The justice of going to war: just cause, right intention, last resort, proportion, and what is not a just cause
• The justice of fighting: the immunity of the innocent, reprisals, sieges and blockades, bombing, terror, and the limits no emergency removes
• The justice of peace: terms, punishment, restitution and occupation
• The questions the old writers did not face: nuclear deterrence, irregular war, mercenaries, drones, cyber attack and autonomous weapons
• Those who answer for war: the soldier, the officer, the citizen, the conscript and the conscientious objector, and the statesman
• Resistance to tyranny, women in combat, and the crusades
• Twelve cases of conscience worked by the principles laid down, from 1776 and the Cuban Missile Crisis to Vietnam, Kosovo and Iraq

Its positions are stated plainly:

• The presumption lies against injustice, not against war.
• A just cause is a wrong received.
• The innocent may never be made the object of attack, whatever the emergency.
• The soldier, the citizen and the statesman each answer for what they do and what they allow.

Written for the Catholic who must decide what he may support, for the priest who must advise him, and for anyone who wants to judge a war by something better than the newspaper.