자위권 행사의 요건으로서의 ‘즉각성’(immediacy)

The purpose of self-defense being to deter or repulse an armed attack from another State, it is permitted in principle only against an on-going attack, as it is confirmed by article 2, paragraph 4, of the United Nations Charter. As such, the right to self-defense should be exercised immediately after the armed attack commences or, at the latest, before the attack ends. However, as the case may be, delayed counterattacks couldn't be deprived of the character of self-defense if the delay in question is justified legally or factually. In fact, it has been suggested that the condition ratio temporis, requirement of immediacy, for the launching of armed counterattack against an act of aggression is to be applied flexibly. This present paper clarifies, above all, the concept and legal basis of the 'immediacy' in self-defense, investigating the conceptual difference between the immediacy of an armed response and the imminence of the attack causing that response. Secondly, the requirement of immediacy is analysed in relation to 'necessity' in self-defense. These two concepts should not be confused, though there exists an interrelationship between them. The latter half of this study concerns the practical application of the immediacy criterion. It should be admitted firstly that immediacy has been required rigorously in case of response to one-off and isolated attacks. On the other hand, it should be emphasized that this criterion has been applied flexibly in various situations: ex post facto armed response with defensive purpose against a past isolated attack; an armed response against a series of attacks which are likely to continue in the future; delayed use of counter-force with a view to restoring territory occupied by an armed attack.