¹ Michael Wood argues that but for McLeod “the world of international law may never have heard of” the Caroline incident. Wood, Michael, The Caroline Incident—1837, in The Use of Force in International Law: A Case-Based Approach 5, 5 (Tom Ruys, Olivier Corten & Alexandra Hofer eds., 2018)Google Scholar.

² Waldock, C.H.M., The Regulation of the Use of Force by Individual States in International Law, 81 Recueil des Cours 451, 463 (1952)Google Scholar.

³ Stephen C. Neff, War and the Law of Nations: A General History 239 (2005).

⁴ Wood, supra note 1, at 11 n. 23; R.Y. Jennings, The Caroline and McLeod Cases, 32 AJIL 82, 91–92 (1938).

⁵ Kellogg Briand Pact, Aug. 27, 1928, 94 LNTS 57.

⁶ Neff, supra note 3, at 304–13.

⁷ Id. at 335. See also id. at 310.

⁸ Charter of the International Military Tribunal, Art. 6(a), Aug. 8, 1945, 59 Stat. 1544, 82 UNTS 279; Judgment, in 22 Trial of the Major War Criminals Before the International Military Tribunal 411, 461–64 (1948). Regarding the understanding of the parties to the conflict, consider the formal declarations of war from 1938 to 1945 compiled in Oona A. Hathaway, William Holste, Scott J. Shapiro, Jacqueline Van De Velde & Lisa Wang, War Manifestos Database (2017), available at http://documents.law.yale.edu/manifestos.

⁹ Oona A. Hathaway & Scott J. Shapiro, The Internationalists: How a Radical Plan to Outlaw War Remade the World 127 (2017).

¹⁰ Wright, Quincy, The Meaning of the Pact of Paris, 27 AJIL 39 (1933)CrossRefGoogle Scholar.

¹¹ Neff, supra note 3, at 304 [emphasis added].

¹² Id. at 311, 313 (arguing that the conflict was treated “de facto if not quite de jure as a case of aggression-and-self-defence instead of war …,” but that “[t]his argument was not advanced in this full and explicit form at the time. Indeed, it would have struck many persons as decidedly odd. …”).

¹³ The prosecutors at Nuremberg advanced something like this argument (although still framing Germany's aggressions as war). Dannenbaum, Tom, Why Have We Criminalized Aggressive War?, 126 Yale L.J. 1242, 1283–84 (2017)Google Scholar; Tom Dannenbaum, The Crime of Aggression, Humanity, and the Soldier 98–99 (2018).

¹⁴ Tom Ruys, “Armed Attack” and Article 51 of the UN Charter: Evolutions in Customary Law and Practice 258, 515 (2010).

¹⁵ Both an increasingly dominant strain of just war theory and international law in this domain are moving away from such exceptionalism. See generally Tom Dannenbaum, War Crimes and Just War Theory, in The Palgrave Handbook of Applied Ethics and the Criminal Law (Larry Alexander & Kimberly Kessler Ferzan eds., forthcoming).

¹⁶ See, e.g., Yoram Dinstein, War, Aggression, and Self-Defence 270 (5th ed. 2012); Paust, Jordan J., Self-Defense Targetings of Non-state Actors and Permissibility of U.S. Use of Drones in Pakistan, 19 J. Transnat'l L. & Pol'y 237, 258–61 (2010)Google Scholar. On the armed conflict issue, see, for example: Gill, Terry D., Classifying the Conflict in Syria, 92 Int'l L. Stud. 353, 366–73 (2016)Google Scholar.

¹⁷ Letter dated 18 April 2001 from the Permanent Representative of the Islamic Republic of Iran to the United Nations addressed to the President of the Security Council, UN Doc. S/2001/381 (Apr. 19, 2001).

¹⁸ See, e.g., Christine Gray, International Law and the Use of Force 236–48 (4th ed. 2018); Ruys, supra note 14 at 528–31. Against the claim that such an action could occur without triggering a state of armed conflict with the host, see International Committee of the Red Cross, Commentary on the First Geneva Convention: Convention (I) for the Amelioration of the Condition of the Wounded and Sick in Armed Forces in the Field, at paras. 257–63 (2d ed. 2016), at https://ihl-databases.icrc.org/ihl/full/GCi-commentary.

¹⁹ See also Gray, supra note 18, at 158 n. 181.

²⁰ Anthea Roberts, Is International Law International? (2017) (see especially ch. 4).

²¹ Wood, supra note 1, at 11, n. 19.

²² For Wood, the French dismissiveness is due to the Webster-Ashburton exchange being an “Anglo-Saxon precedent.” Id. However, Roberts shows that French and American textbooks are the most Western-centric among those of the permanent five members of the Security Council. Roberts, supra note 20, at 167. It seems improbable that an incident eschewed by French textbooks as too Anglo-Saxon is likely to feature prominently in Russian or Chinese texts.

²³ Theodora Christodoulidou & Kalliopi Chainoglou, The Principle of Proportionality from a Jus Ad Bellum Perspective, in The Oxford Handbook of the Use of Force in International Law 1187, 1189 (Marc Weller ed., 2015); Gray, supra note 18, at 157.

²⁴ Consider the 2017 statements of the British and Australian attorneys general, each of whom cited the Caroline, reinterpreted imminence in light of shifting necessities, and asserted ultimately a flexible and expansive view of imminence as a constraint on the use of force: The Rt Hon Jeremy Wright QC MP, The Modern Law of Self-Defence (Jan. 11, 2017), at https://www.ejiltalk.org/the-modern-law-of-self-defence; Senator the Hon George Brandis QC, The Right of Self-Defence Against Imminent Armed Attack in International Law (Apr. 11, 2017), at https://www.ejiltalk.org/the-right-of-self-defence-against-imminent-armed-attack-in-international-law.

²⁵ Contrast: Report of the UN Secretary General's High Level Panel on Threats, Challenges and Change, A More Secure World: Our Shared Responsibility, para. 188, UN Doc A/59/565 (Dec. 2, 2004). Forcese emphasizes the epistemic danger of subsuming imminence to necessity (p. 230). Although sympathetic to the notion that imminence may need to be stretched on necessity grounds, Dapo Akande and Thomas Liefländer argue that it should also be understood to include considerations of the “likelihood and gravity” of a pending armed attack and that “temporal factors” are relevant to both. Akande, Dapo & Liefländer, Thomas, Clarifying Necessity, Imminence, and Proportionality in the Law of Self-Defense, 107 AJIL 563, 565 (2013)Google Scholar

²⁶ Roberto Ago, Addendum to the Eighth Report on State Responsibility, II(1) Y.B. Int'l L. Comm'n 13, 69 para. 121 (1980), UN Doc. A/CN.4/318/ADD.5-7; Military and Paramilitary Activities in and Against Nicaragua (Nicar. v. U.S.), Merits, 1986 ICJ Rep. 14, paras. 211–14 (June 27) (Schwebel, J. dissenting); Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion, 1996 ICJ Rep. 226, para. 5 (July 8) (Higgins, J. dissenting); Armed Activities on the Territory of the Congo (Dem. Rep. Congo v. Uganda), Merits, 2005 ICJ Rep 168, paras 33–34 (Dec. 19) (Kooijmans, J. dissenting).

²⁷ Christodoulidou & Chainoglou, supra note 23, at 1190–91. Distinguishing proportionality vis-à-vis the attack or threat and proportionality vis-à-vis the pursued objective, see Akande & Liefländer, supra note 25, at 566.

²⁸ David Kretzmer, The Inherent Right to Self-Defence and Proportionality in Jus Ad Bellum, 24 Eur. J. Int'l L. 235, 238–40 (2013).

²⁹ Antonio Cassese, International Law 355 (2d ed. 2005); Christodoulidou and Chainoglou, supra note 23, at 1192, 1199; Vaughan Lowe, Clear and Present Danger: Responses to Terrorism, 54 Int'l & Comp. L. Q. 185, 192–93 (2005); Kretzmer, supra note 28, at 277–79. The ICJ seems to have combined these tests in its jurisprudence, although its articulation of the narrow proportionality aspect has sometimes taken more of a tit-for-tat flavor. Armed Activities, supra note 26, at 223 para. 147; Military and Paramilitary Activities, supra note 26, para. 237

³⁰ Judith Gardam, Necessity and Proportionality in Jus ad Bellum and Jus in Bello, in International Law, the International Court of Justice and Nuclear Weapons 275, 280 (Laurence Boisson de Chazournes & Philippe Sands eds., 1999); Eliav Lieblich, On the Continuous and Concurrent Application of ad Bellum and in Bello Proportionality, in Necessity and Proportionality in International Peace and Security Law (Claus Kress & Robert Lawless eds., forthcoming).

³¹ Kretzmer, supra note 28, at 268–69; Nolte, Georg, Multipurpose Self-Defence, Proportionality Disoriented: A Response to David Kretzmer, 24 Eur. J. Int'l L. 283 (2013)CrossRefGoogle Scholar; Akande and Liefländer, supra note 25, at 568–69.

³² Hathaway and Shapiro, supra note 9, ch. 13, 418.

³³ Criticizing the metric: Michael J. Glennon, How Not to End War, Lawfare (Oct. 18, 2017), at https://www.lawfareblog.com/how-not-end-war.

³⁴ Hathaway and Shapiro, supra note 9, at 314–33.

³⁵ 6 The Report of the Iraq Inquiry HC 264, at 621, para. 384 (2016).

³⁶ See Shane Darcy, Military Force Against Syria Would Be a Reprisal Rather than Humanitarian Intervention, but that Doesn't Make It Any More Lawful, EJIL:Talk! (Sept. 1, 2013), at https://www.ejiltalk.org/military-force-against-syria-would-be-a-reprisal-rather-than-humanitarian-intervention-but-that-doesnt-make-it-any-more-lawful; Milena Sterio, Military Intervention in Syria: The International Law Framework, Intlawgrrls (Aug. 27, 2013), at https://ilg2.org/2013/08/27/military-intervention-in-syria-the-international-law-framework. Arguing that a humanitarian intervention rationale would have been applicable, see UK Prime Minister's Office Policy Paper, Chemical Weapon Use by Syrian Regime: UK Government Legal Position (Aug. 29, 2013), at https://www.gov.uk/government/publications/chemical-weapon-use-by-syrian-regime-uk-government-legal-position/chemical-weapon-use-by-syrian-regime-uk-government-legal-position-html-version.

³⁷ International Committee of the Red Cross, supra note 18, para. 262.