Thoughts on the Caroline Doctrine


In 1837, US Secretary of State Daniel Webster articulated a definition of self defence, which evolved into customary international law.16 Webster’s definition followed what has come to be known as the Caroline incident. The Caroline was a US steamboat attempting to transport supplies to Canadian insurgents.17 A British force interrupted the Caroline’s voyage, shot at it, set it on fire and let it wash over Niagara Falls. Webster said that Britain’s act did not qualify as selfdefence because self-defence is only justified ‘if the necessity of that self-defence is instant, overwhelming, and leaving no choice of means, and no moment for deliberation.’18 According to Webster, Britain could have dealt with the Caroline in a more diplomatic manner. The Caroline Doctrine limits the right to self-defence to situations where there is a real threat, the response is essential and proportional, and all peaceful means of resolving the dispute have been exhausted. Article 51 of the UN Charter 19 narrowed self-defence, making it permissible only in the event of an armed attack.

The UN Charter sought to articulate a world order devoid of military conflict.21 In an effort to avoid repeating the horrors of the Second World War, the UN Charter calls on nation states to peacefully resolve their conflicts. ‘The purpose of the United Nations is to save the succeeding generations from the scourge of war.’22 ‘All Members shall settle their international disputes by peaceful means’23; ‘All Members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations.’24 To that end, the UN Charter sought to limit when states could implement self-defence against other nation states. Article 51 authorises self-defence only if armed attack ‘occurs.’25 Nothing in the present Charter shall impair the inherent right of individual or collective self-defence 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-defence 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.26 This is a narrowing of the Caroline doctrine that provided for anticipatory self-defence provided the threat to national security is reasonably believed to be imminent. 27 Article 51’s concept of pre-emption has been significantly reduced from the Caroline doctrine. The significance of this narrowing cannot be underestimated—from a customary international law principle enabling preemption to a treaty-based definition of self-defence dependent upon the occurrence of an armed attack.

While Article 51 clearly expresses the obligation of nation states to prevent war, Lobel has suggested the following: The United Nations Charter prohibits the use of force except when authorised by the Security Council or when undertaken by individual nations in self-defence and in response to ‘an armed attack.’ Moreover, as a general matter, the United Nations has sought to limit the Article 51 self-defence exception to prevent its misuse. First, Article 51 permits only those actions taken in self-defence; reprisals and retaliations are proscribed under the U.N. Charter. In other words, a nation can respond to an ongoing attack, including one waged by a terrorist organisation, by using force. However, that nation may not forcibly retaliate against another in response to an unlawful act that the latter committed against the former in the past. The reasoning behind this rule is simple: a nation subject to an ongoing attack cannot be expected to wait for the international community’s aid before fighting back. Obviously, when a nation is under attack, immediate action is necessary. On the other hand, a nation whose citizens are no longer being attacked must seek U.N. intervention; to allow military reprisals would be to encourage the renewed use of force. This would result in a spiralling escalation of violence. Thus, the U.S. government, most state actors, the U.N. Security Council, and the International Court of Justice have offi- cially taken the position that armed reprisals are outlawed.28 The fundamental question facing decision makers in the context of selfdefence is when pre-emptive actions can be undertaken. Pre-emptive action is predicated on intelligence information that must meet the reliability and corroborated standard this article seeks to forcefully advocate. Furthermore, for pre-emptive action to be legitimate it must be proportional in the context of the attack it is intended to prevent.29 The threat must be concrete, not vague based on loosely gathered intelligence that may be more fantasy than fact.30 In determining proportionality, decision makers must determine both the immediacy of the threat and its severity.

Customary international law permits a state to respond to a threat and infringe on the territorial sovereignty of another nation when four criteria are met: (i) it is acting in self-defence; (ii) the attack is substantial and military (i.e., not an ‘isolated armed incident’); (iii) the offending nation is complicit, unwilling, or unable to prevent further attacks; and (iv) the attack is widespread and imminent.32 States, in order to adequately defend themselves, must be able to take the fight to the terrorist before the terrorist takes the fight to it. From experience gained over the years, the state must act pre-emptively in order to either deter terrorists or, at the very least, prevent terrorism. The question that must be answered, both from a legal and policy perspective, is what tools are necessary for the state to combat terrorist bombings? Active self-defence would appear to be the most effective tool; that is, rather than wait for the actual armed attack to ‘occur’ (Article 51), the state must be able to act anticipatorily (Caroline) against the non-state actor (not considered in Caroline). The development of a new body of international law providing legal justification for such actions (active self-defence against a non-state actor) must be consistent with existing principles and obligations such as proportionality, military necessity, collateral damage and exhaustion or unavailability of a peaceful alternative. The two concepts, active self-defence and the four fundamental principles listed above, are not in conflict; rather, they are critical to formulating international law’s response to modern ‘warfare’, which is clearly a very different ‘war’ than traditional state v state conflict. In undertaking operational counter terrorism, decision makers are increasingly faced with the following dilemma: whether an action, either responsive or preventive, can be undertaken even if it involves violating the sovereignty of another nation state. In violating the sovereignty of another nation-state under the banner of self-defence, it can be argued that there is an implicit determination that the violated state is a failed state.

As an example, in response to a terror attack in Israel, the Israeli air force attacked terrorist bases in Syria.33 Though Israel was widely criticized,34 the Government explained that the target was not Syria; rather the Israeli Air Force (IAF) was attacking terrorist bases located in Syria with no intent to violate Syrian sovereignty. This argument would appear disingenuous as Syrian sovereignty was clearly violated by the breach of Syrian airspace by the IAF. In contrast, the reported IAF attack on a Syrian target(s) is substantially different; the previous raid was on terrorist bases located in Syria whereas the most recent attack (if media reports are accurate) was aimed at specific Syrian targets. Similarly, USA violated Sudanese and Afghanistan sovereignty when the US Air Force, in response to the 1998 embassy bombings in Kenya and Tanzania, attacked targets in those two countries. USA fired seventy-nine tomahawk missiles at alleged bin Laden outposts in Sudan and Afghanistan, including a factory believed to produce chemical weapons. President Clinton relied on traditional Article 51 self-defence in justifying the act, but added that the strikes ‘were a necessary and proportionate response to the imminent threat of further terrorist attacks against U.S. personnel and facilities. While the attack may be considered to be retaliatory rather than self-defence in nature, the question of anticipatory self-defence is relevant to this attack. If, as had been reported,40 the factory was indeed producing chemical weapons then an argument could be made that America, and America’s allies would potentially be at danger. We shall return to this attack in Section 3.

Following the 9/11 attacks, the UN Security Council passed two resolutions addressing appropriate responses to terrorism, UN Security Council Resolution 136841 and 1373.42 Relevant passages of UN Security Council Resolution 1368 are: The Security Council, Reaffirming the principles and purposes of the Charter of the United Nations, Determined to combat by all means threats to international peace and security caused by terrorist acts, Recognizing the inherent right of individual or collective self-defence in accordance with the Charter, … 3. Calls on all States to work together urgently to bring to justice the perpetrators, organizers and sponsors of these terrorist attacks and stresses that those responsible for aiding, supporting or harbouring the perpetrators, organizers and sponsors of these acts will be held accountable; 4. Calls also on the international community to redouble their efforts to prevent and suppress terrorist acts including by increased cooperation and full implementation of the relevant international anti-terrorist conventions and Security Council resolutions, in particular resolution 1269 (1999) of 19 October 1999; 5. Expresses its readiness to take all necessary steps to respond to the terrorist attacks of 11 September 2001, and to combat all forms of terrorism, in accordance with its responsibilities under the Charter of the United Nations; …43 And Resolution 1373: The Security Council, Reaffirming its resolutions 1269 (1999) of 19 October 1999 and 1368 (2001) of 12 September 2001, … Reaffirming further that such acts, like any act of international terrorism, constitute a threat to international peace and security, Reaffirming the inherent right of individual or collective self-defence as recognized by the Charter of the United Nations as reiterated in resolution 1368 (2001), … 2. Decides also that all States shall: … (b) Take the necessary steps to prevent the commission of terrorist acts, including by provision of early warning to other States by exchange of information; … 3. Calls upon all States to: … (c) Cooperate, particularly through bilateral and multilateral arrangements and agreements, to prevent and suppress terrorist attacks and take action against perpetrators of such acts; ..


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