UN Article 51 - The Legal Basis for Preemption

Author: William H. Taft IV
November 18, 2002
Council on Foreign Relations

MEMORANDUM

To: Members of the ASIL-CFR Roundtable

From: William H. Taft, IV, Legal Adviser , Department of State

Subject: Old Rules, New Threats

“We no longer live in a world where only the actual firing of weapons represents a sufficient challenge to a nation’s security to constitute maximum peril.” President Kennedy spoke those words in the context of the Cuban Missile Crisis in 1962. I use them today to demonstrate that preemptive action in self-defense is not a novel concept. The United States, when threatened with weapons of mass destruction, has taken preemptive action to preserve the safety of its people. However, in 1962, the United States did not specifically rely on a right of preemptive self-defense, preferring the terms of the Rio Treaty and concepts within Article 51 of the United Nations Charter.

Article 51 of the United Nations Charter makes clear that “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.” The United States has long held that, consistent with Article 51 and customary international law, a state may use force in self-defense: 1. if it has been attacked, or 2. if an armed attack is legitimately deemed to be imminent. This interpretation is also consistent with our domestic notion of self-defense as applied in the criminal and tort law contexts.

The case is, without question, easier where there has been a clear attack or where there has been a direct authorization from the United Nations Security Council. After the terrible attacks of 9/11, the United States, with the cooperation of its allies, launched an attack against Al Qaeda and the Taliban. This action could be considered preemptive, in a sense, as the United States was not acting in retaliation, but actually, to prevent and deter imminent attack. If it were necessary to apply the test of necessity before action, the events of that September could be viewed as establishing that the enemy intended to attack again. Applying this theory, after the first aggressive strike, United States action was justified so long as the enemy maintained his capacity to attack. But the question remains, short of an actual armed attack, how long does a State have to wait before preemptive measures can be taken to prevent serious harm? In the era of weapons of mass destruction, definitions within the traditional framework of the use of force in self-defense and the concept of preemption must adapt to the nature and capabilities of today’s threats.

Within the traditional framework of self-defense, a preemptive use of proportional force is justified only out of necessity. The concept of necessity includes both a credible, imminent threat and the exhaustion of peaceful remedies.

First, an imminent threat can most easily be visualized as an advancing army or ships on the horizon. But how far away from that picture can one be removed and still view the situation as one where the enemy’s preparation makes it necessary to view an attack as imminent?

In 1837, the British destroyed the Caroline, a U.S. steamer, not in response to a prior attack, but because they anticipated its use to support Canadian forces in their rebellion against the crown. This anticipation was based on its record of past support for the rebels. Secretary of State Daniel Webster is often quoted, from his correspondence with British Foreign Minister Lord Ashburton, justifying action in self-defense in situations “leaving no choice of means and no moment for deliberation.” However, throughout the collection of documents, the Secretary uses several other characterizations as well, such as, “most urgent and extreme necessity,” “pressing or overruling necessity,” “strong, overpowering necessity,” “clear and absolute necessity,” “and “ a necessity, present and inevitable, for attacking.” The focus of these descriptions was on urgency rather than just the timing of the response and, above all, on the necessity of using force to protect against future harm.

Neither Webster nor Ashburton disagreed about the existence of an inherent right to use force in self-defense, but rather on its application to the set of facts before them. In fact, Secretary Webster pointed out, “the extent of this right is a question to be judged by the circumstances of each particular case.” The difficulty lies in determining, as Lord Ashburton asked, “when begins your right to self-defend.”

The purpose of the UN Charter’s language preserving the inherent right of self-defense is to help dissuade states from taking aggressive action. Underlying this purpose was the assumption that when a nation was attacked, it would be able to respond. The concept of armed attack and imminent threat must now take into account the capacity of today’s weapons. The deterrent effect is diminished when the magnitude of the first aggressive strike could destroy completely one’s ability to respond. The inherent right of self-defense embodied in the UN Charter must include the right to take preemptive action; otherwise the original purpose is frustrated. We cannot wait for a first strike under such circumstances. The simple fact that a state possesses significant military power or seeks to enhance it would not, in the absence of any evidence that it intends to use its power against others aggressively, justify a preemptive strike against it. This is to say that the United States or any other nation should not use force to preempt any emerging threat or as a pretext for aggression. As Secretary Webster said, we must consider seriously “the circumstances of each particular case.”

Take a more recent examination of a claim of the preemptive use of force in self-defense. In June of 1981, Israel destroyed an Iraqi nuclear reactor near Baghdad. Israel asserted the attack was undertaken in self-defense, claiming that Iraq planned to use the reactor to build nuclear weapons for use against Israel. On consideration, the United Nations Security Council unanimously condemned the act as an act of aggression in violation of the UN Charter.

Interestingly, the discussion at the UN was not focused on the scope of the right of self-defense. Only six of the fifteen members made any reference to the topic. Of those, only two countries, Spain and Mexico, clearly indicated their preference for the narrowest interpretation of Article 51, that an actual armed attack must have taken place to justify force in self-defense. The majority of the debate centered on whether Israel’s actions were a legitimate exercise of the right to self-defense. More accurately, the members debated the “necessity” of Israel’s actions.

The Member Nations agreed that Israel had failed to exhaust all peaceful means for resolution of the conflict. In fact, this was the sole reason given by the United States as an explanation for its conclusion that Israel had violated the Charter. Furthermore, nearly every member pointed to the factual evidence revealing that the Iraqi reactor was in full compliance, at the time, with its obligations under the Non-Proliferation Treaty. Many believed the threat was too tenuous, as the Iraqi facility would have required radical alteration to produce weapon components.

The chief concern of the Members in 1981, and likely of the world today, were the implications of Israel’s justification of the attack. Many viewed the rationale as an unlimited concept of self-defense against all possible future dangers, subjectively assessed. This would certainly have been a dangerous precedent to set, if permitted without “clear and absolute necessity.” However, the members had imposed limits by evaluating the individual circumstances of the situation against the tests of necessity and proportionality. In the eyes of the United Nations, Israel had not met the exacting standards of that test.

The President’s National Security Strategy relies upon the same legal framework applied to the British in Caroline and to Israel in 1981. The United States reserves the right to use force preemptively in self-defense when faced with an imminent threat. While the definition of imminent must recognize the threat posed by weapons of mass destruction and the intentions of those who possess them, the decision to undertake any action must meet the test of necessity. After the exhaustion of peaceful remedies and a careful, deliberate consideration of the consequences, in the face of overwhelming evidence of an imminent threat, a nation may take preemptive action to defend its nationals from unimaginable harm.

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