¹ There is great terminological confusion on this question, especially between the terms “preventive” war and “preemptive” war. In this essay, I will use “preventive” to mean the use of force before there is even an imminent threat, and “preemptive” to mean the use of force only when the threat has become imminent.

² “The National Security Strategy of the United States of America” (September 2002); available at http://www.whitehouse.gov/nsc/nss.pdf. The document speaks of “preemptive” action rather than “preventive,” and does not make a clear distinction between the two (e.g., its call for “adapting” the requirement of imminence [p. 19] is ambiguous between preserving imminence and eliminating it). But it is widely taken as an implicit endorsement of preventive force, a conclusion that is confirmed by Bush's Meet the Press remarks.

³ The resolution passed by the overwhelming margin of 1202 to 263. See http://www.apa.udel.edu/apa/divisions/eastern.

⁴ Buchanan, Allen and Keohane, Robert O. , “ The Preventive Use of Force: A Cosmopolitan Institutional Proposal ,” Ethics & International Affairs 18, no. 1 (2004 ) pp. 1 – 22 . They cite only Michael Walzer for this claim, and clearly do not base it on a detailed analysis of the just war tradition.CrossRefGoogle Scholar

⁵ Garry Wills, “What Is a Just War?”New York Review of Books, November 18, 2004, pp. 32–35; and Paul Savoy, “The Moral Case against the Iraq War,”Nation, May 31, 2004, pp. 16–20.

⁶ Paul Ramsey, The Just War (Lanham, Md.: Rowman & Littlefield, 2002), pp. 61–69.

⁷ Hugo Grotius, The Rights of War and Peace (1625), trans. A. C. Campbell (Boston: Elibron Classics, 2003), p. 76.

⁸ Emmerich de Vattel, The Law of Nations (1758), trans. Joseph Chitty (Philadelphia: T. & J. W. Johnson & Co., 1883), bk. III, ch. 3, sec. 26.

⁹ Ibid., sec. 28.

¹⁰ Alberico Gentili, De Jure Belli Libri Tres (1612), trans. John C. Rolfe (Oxford: Clarendon Press, 1933), bk. I, ch. XIV.

¹¹ The justification for a punitive war is ambiguous, as we have already seen in the Grotius quotation above. The goal of a punitive war may be to avenge past wrongs and to restore what was taken, or it may be to prevent future dangers (that is, a punitive war can also be a preventive war), just as modern theories of punishment allow for multiple purposes.

¹² See also Richard Tuck, The Rights of War and Peace (New York: Oxford University Press, 1999), pp. 18–31, for a survey of the support for the principle of preventive war among various just war thinkers. For a contrary view, see Jonathan Barnes, “The Just War,” in Norman Kretzmann, Anthony Kenny, and Jan Pinborg, eds., The Cambridge History of Later Medieval Philosophy (Cambridge: Cambridge University Press, 1982), pp. 771–84. Barnes argues that medieval just war theory did not permit “anticipatory wars” where there was an imminent threat; a fortiori, it did not permit preventive wars. For Barnes, “the appropriate (and prudent) response to a threat is mobilization and military vigilance, for that guards against the danger and preserves the possibility of peace” (p. 779). Barnes, however, conflates the just cause requirement with the necessity requirement (which Barnes recognizes is “implicit in every statement of the [just war] theory” [p. 783]). If there are adequate means of self-protection short of war, it follows that war is impermissible. The point rather is that if preventive war is judged to be necessary, the tradition held that it was legitimate.

¹³ Grotius, The Rights of War and Peace, p. 77.

¹⁴ Samuel Pufendorf, On the Law of Nature and of Nations (1672), trans. Basil Kennett (London: J. Walthoe, R. Wilken, 1729), bk. II, ch. V, sec. 6, p. 145.

¹⁵ Gentili, De Jure Belli, p. 62.

¹⁶ Vattel, The Law of Nations, bk. II, ch. 4.

¹⁷ Gentili, De Jure Belli, p. 66.

¹⁸ Pufendorf, On the Law of Nature, p. 145.

¹⁹ Francisco de Vitoria, Political Writings, ed. Anthony Pagden and Jeremy Lawrance (Cambridge: Cambridge University Press, 1991), p. 316, quoted in Wills, “What Is a Just War?”.

²⁰ Vitoria, Political Writings, pp. 316, 305.

²¹ Samuel Pufendorf, On the Duty of Man and Citizen (1673), ed. James Tully (Cambridge: Cambridge University Press, 1991), bk. I, ch. 5, sec. 11, p. 50.

²² Notably, the contribution of David Luban , “ Preventive War ,” Philosophy & Public Affairs 32, no. 3 (2004 ). See also John Yoo, “Using Force,”University of Chicago Law Review 71 (Summer 2004), pp. 729–32 (defending what he calls instrumentalism, but which is just another name for a form of consequentialism, in which actions are judged by a cost-benefit analysis in terms of their tendency to lead to the goal of international stability).Google Scholar

²³ Note that this is not to claim that preventive war is grounded in self-defense, but rather that both have a common moral foundation.

²⁴ Gentili, De Jure Belli, p. 62.

²⁵ Jeff McMahan, “Realism, Morality, and War,” in Terry Nardin, ed., The Ethics of War and Peace (Princeton: Princeton University Press, 1996), p. 85.

²⁶ Vattel, The Law of Nations, bk. II, ch. 4, sec. 50.

²⁷ This position is indeed quite reasonably stated in the 2002 National Security Strategy, especially where the threat is particularly great: “The greater the threat, the greater is the risk of inaction—and the more compelling the case for taking anticipatory action to defend ourselves, even if uncertainty remains as to the time and place of the enemy's attack.”“National Security Strategy,” p. 19.

²⁸ See Maggie Lawson, “The Fatal Legend of Preemptive War,”National Catholic Reporter, February 27, 2004, p. 19.

²⁹ See Gregory Reichberg, “Preemptive War,”Commonweal, January 30, 2004, pp. 9–10. Compare discussion in Luban, “Preventive War,” p. 228, suggesting that prevention is justified against rogue states such as Nazi Germany or Hussein's Iraq.

³⁰ See also Jeff McMahan's use of the domestic analogy argument in “Realism, Morality, and War,” p. 85. David Rodin recently argued against the legitimacy of the domestic analogy in his book War and Self-Defense (New York: Oxford University Press, 2002). His objection, however, applies only if one accepts his account of defensive or preventive force as grounded in the possession of a natural right. Under this framework, the defender of the analogy would be forced to reify the state into a right-bearing entity. There is good reason to reject the rights theory of self-defense, however, in which case Rodin's objection disappears. See my “Is There a ‘Right’ to Self-Defense,”Criminal Justice Ethics 23, no. 1 (2004), pp. 20–32.

³¹ Grotius, The Rights of War and Peace, p. 75. See also Vattel, bk. III, ch. 3, sec. 28 (stating the three lawful objects of war: recovering what has been taken, providing for future safety, defending ourselves).

³² Gentili, De Jure Belli, p. 70.

³³ See, e.g., Pufendorf, On the Duty of Man and Citizen, bk. I, ch. 5, sec. 9. I develop this argument at much greater length in my “Self-Defense, Imminence and the Battered Woman” (manuscript in preparation).

³⁴ There is of course substantial debate about the legal basis for the 2003 Iraq war—i.e., whether it was authorized by previous Security Council resolutions, or whether it was in violation of those resolutions but justified nonetheless as a case of preventive war. See, e.g., William Bradford, ‘“The Duty to Defend Them’: A Natural Law Justification for the Bush Doctrine of Preventive War,”Notre Dame Law Review 79 (July 2004), p. 1369, n. 16. Here I will sidestep this debate and ask the question whether the Iraq war could be justified considered solely as a preventive war, even without (or contrary to) the approval of the UN.

³⁵ See, e.g., Pufendorf, On the Duty of Man and Citizen, bk. I, ch. 5, sec. 8, p. 49.

³⁶ Article 51 of the Charter reads in full: “Nothing in the present Charter shall impair the inherent right of individual or collective self-defense if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security. Measures taken by Members in the exercise of this right of self-defense shall be immediately reported to the Security Council and shall not in any way affect the authority and responsibility of the Security Council under the present Charter to take at any time such action as it deems necessary in order to maintain or restore international peace and security.”.

³⁷ Yoo, “Using Force,” p. 738.

³⁸ Ramsey, The Just War, p. 65.

³⁹ “National Security Strategy,” p. 12. This passage is ambiguous (perhaps deliberately) between the use of force preventively and force in self-defense. Although it speaks of self-defense, its meaning seems clearly to be preventive force (“identifying and destroying the threat before it reaches our borders,”“prevent them from doing harm”)

⁴⁰ Yoo, “Using Force,” p. 781.

⁴¹ Bradford, “‘The Duty to Defend Them,’” p. 1370.

⁴² Arend, Anthony , “ International Law and the Preemptive Use of Military Force ,” Washington Quarterly 26, no. 2 (Spring 2003 ), p. 101.CrossRefGoogle Scholar

⁴³ Glennon, Michael , “ The Fog of Law: Self-Defense, Inherence, and Incoherence in Article 51 of the United Nations Charter ,” Harvard Journal of Law and Public Policy 25 (Spring 2002 ), p. 540.Google Scholar

⁴⁴ Franck, Thomas , “ When, If Ever, May States Deploy Military Force without Prior Security Council Authorization ?” Washington University Journal of Law and Policy 5 (2001 ), pp. 51 – 52.Google Scholar

⁴⁵ Vitoria, Political Writings, p. 302.

⁴⁶ Brian Urquhart, “The New American Century?”New York Review of Books, August 11, 2005, p. 41.

⁴⁷ Ramsey, Michael , “ Reinventing the Security Council: The U.N. as a Lockean System ,” Notre Dame Law Review 79 (July 2004 ), p. 1558.Google Scholar

⁴⁸ Falk, Richard , “ What Future for the UN Charter System of War Prevention ?” American Journal of International Law 97 (July 2003 ), quoted in Ramsey, “Reinventing the Security Council,” p. 1540.CrossRefGoogle Scholar

⁴⁹ Ramsey, “Reinventing the Security Council,” p. 1562.

⁵⁰ Ibid., p. 1540.

⁵¹ Ramsey appears to have conflated the just war requirement that war be a “last resort” with the requirement that the threat be imminent; the latter requirement applies only to wars in self-defense, but the former applies to all wars. See Ramsey, “Reinventing the Security Council,” p. 1530(“force should be used only as a last resort, as a response to actual attack or imminent threats of attack”).

⁵² To be sure, some countries (e.g., Pakistan) did indicate that there was no evidence of an imminent threat to international peace. But their position seems to have been not that it would be illegal to act absent an imminent threat, but rather that it would be imprudent and unnecessary given the availability of satisfactory peaceful alternatives (e.g., inspections). France's position seems to have been that the Iraq war failed the necessity rule, not the imminence rule, in that more time was needed to see if the inspections would work before invading.

⁵³ Ramsey, “Reinventing the Security Council,” p. 1534.

⁵⁴ Vattel, The Law of Nations, bk. I, ch. 17, sec. 202. Vattel also wrote, “When, therefore, a city or a province is threatened or actually attacked, it must not, for the sake of escaping the danger, separate itself from the state of which it is a member, or abandon its natural prince, even when the state or the prince is unable to give it immediate and effectual assistance. Its duty, its political engagements, oblige it to make the greatest efforts, in order to maintain itself in the present state” (sec. 201).

⁵⁵ Henry Kissinger, “Our Intervention in Iraq,”Washington Post, August 12, 2002, p. A15, quoted in Luban, “Preventive War,” p. 227.

⁵⁶ Franck, “When, If Ever, May States Deploy Military Force,” p. 62.