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PRE-EMPTIVE SELF-DEFENCE - Meaning and Legality under International Law

Updated: Jan 22, 2020


In view of the language used in Article 51, can it be said that a right of anticipatory or pre-emptive self-defence is available to a State? Anticipatory self-defence means use of force by a State to repel an attacker before an actual attack has taken place or before the army of the enemy has crossed its border or before the bombs of the enemy have fallen upon its territory.

"Anticipatory" is a term that "refers to the ability to foresee consequences of some future action and take measures aimed at checking or countering those consequences

As per the strict interpretation of Article 51, the right of self-defence can be exercised against an actual armed attack. In other words, the right of anticipatory or pre-emptive self-defence is not available to a State.

This, however, may cause practical problems, e.g. the use of modem weapons by a State may hardly give any time to the other State to react. With the growing availability of ever more sophisticated nuclear, biological and chemical weapons capable of destroying entire cities, if not nations, and with the development to delivery systems impervious to interception, no nation could seriously be expected to await an actual armed attack before acting to head it off."

It has been argued that "Article 2(4) of the Charter requires Members to refrain not only from the use of force, but also from the threat of force. If States had to wait for a armed attack to occur, then maintenance of international peace and security could not take place.

If States waited for Such an attack, they would then become responsible for the restoration, instead of maintenance, of international peace and security.

It has been suggested that the notion of self-defence could be expanded to a right of "pre-emptive self-defence" which is also referred to as "preventive self-defence" enabling the use of force in order to defend against, or prevent possible attacks. It may, however, create a serious problem.

If the States are allowed to exercise the right of anticipatory or pre-emptive self-defence, there shall always be a likelihood to its misuse. An early pre-emptive right may also result in aggression.

The right of self-defence, therefore, cannot be exercised merely on the ground of expectations anticipations, and fear. It is required to be proved that the other side is already embarked on an inevitable course of action. Professor Greenwood argues:

  • The right of anticipatory self-defence is quite narrowly defined. Ever since the United Kingdom-US exchange in what has become known as the Caroline case in 1837-38.

  • The right has been confined to instances where the threat of armed attack was imminent In my opinion, that still reflects international law and, in so far as talk of a doctrine of 'pre-emption' is intended to refer to a broader right to respond to threats, which might materialise sometime in the future, I believe that such a doctrine has no basis in law.

The scope of right of self-defence of a State is limited. The entitlement of States to resort to self-defence is subject to certain constraints. Some of these constraints are inherent in the very concept of self-defence. Other requirements are specified in Article 51.

The Caroline incident has put the right of self-defence in two core principles: necessity and proportionality. Necessity demands that the danger be "instant, overwhelming, leaving no choice of means, and no moment for deliberation".

Proportionality means that "nothing unreasonable or excessive" may be done because the act must be distinctly limited by the necessity causing it. These principles were widely used in international disputes and rapidly came to represent the customary law of self-defence.

Accordingly, Article 51 of the UN Charter incorporated the Caroline principles as pillars of the "inherent" state right of self-defence. Since 1945, States have continued to consider necessity and proportionality the defining parameters of appropriate self-defence.

In Advisory Opinion on Legality of the Threat or Use of Nuclear Weapons," the ICJ stated that "the submission of the exercise of the right of self-defence to the conditions of necessity and proportionality is a rule of customary international law".

It further stated that "this dual condition applies equally to Article 51 of the Charter, whatever the means of force employed".

On the use of nuclear weapons in self-defence, the ICJ made the following observations:

The proportionality principle may thus not in itself exclude the use of nuclear weapons in self-defence in all circumstances.

But at the same time, a use of force that is proportionate under the law of self-defence, must, in order to be lawful, also meet the requirements of the law applicable in armed conflict which comprise in particular the principles and rules of humanitarian law."

The ICJ finally concluded by stating that ".. however, in view of the current state of international law, and of the elements of fact at its disposal, the Court could not conclude definitively whether the threat or use of nuclear weapons would be lawful or unlawful in an extreme circumstance of self-defence, in which the very survival of a State would be at stake".

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