Commentary: Rein Milllerson

• Author: Rein Milllerson
• Pages: 443

I find the presentations of Professor Roberts and Professor Wedgwood very stimulating indeed. There are observations with which I am in complete agreement and it only remains to me to emphasize their significance. At the same time, there are also some points in both papers that, in my opinion, call for clarification or dispute.

First, about the relationship, discussed here by various speakers, between jus ad bellum and jus in bello. These branches of international law are separate in the sense that notwithstanding the status of parties of an armed conflict in the light ofjus ad bellum (i.e., notwithstanding whether one is an aggressor or a victim of aggression), they are equal in the light ofjus in bello. In that respect, the International Court of Justice (ICJ) in the advisory opinion on Nuclear Weapons created a novelty distinguishing between 'an extreme circumstance of self-defense, in which the very survival of a State would be at stake'1 and other circumstances. Only in the former circumstances, as the Court said, it 'cannot conclude definitively whether the threat or use of nuclear weapons would be lawful or unlawful.'2 Paragraph 105 (2) E of the advisory opinion seems to indicate, on the one hand, that in all other circumstances the use of (or threat to use) nuclear weapons is unlawful, i.e., contrary to international humanitarian law. On the other hand, such a formula seems to make what would otherwise be unlawful under jus in bello lawful (or at least not necessarily unlawful) because of different status of parties in the light of jus ad bellum.

1. Advisory Opinion on the Legality of the Threat or Use of Nuclear Weapons, 1996 I.C.J. 78, ~ 105(2)E (uly 8) [hereinafter Advisory Opinion on Nuclear Weapons].

2. Id.

   Injus ad bellum the concept of survival of a State may be expressed through the right to self-defense. Obviously, only a victim of an armed attack, and not its perpetrator, has such a right. A State that has committed an armed attack does not have the right to self-defense even if its survival is at stake as a result of measures taken in self-defense.3 In jus in bello the victim's right to survival may be expressed through the concept of military necessity. As Judge Higgins, dealing with possible use of nuclear weapons, wrote in her Dissenting Opinion:

   It must be that, in order to meet the legal requirement that a military target may not be attacked if collateral civilian casualties would be excessive in relation to military advantage, the 'military advantage' must indeed be one related to the very survival of a State or the avoidance of infliction (whether by nuclear or other weapons of mass destruction) of vast and severe suffering on its own population: and that no other method of eliminating this military target be available.4

   This carefully formulated passage does not, however, explain why only a State acting in self-defense may use nuclear weapons as a last resort when its survival is at stake. Assuming that even a victim of an armed attack has to observe requirements of jus in bello, the only explanation seems to be that by committing an armed attack the aggressor has forfeited its right to survival expressed through the concept of self-defense. In that way, a wrong done in the light ofjus ad.bellum has an impact on jus in bello since the concept of survival crosses both branches of international law. The victim's right to survival raises the bar against which military advantage resulting, for example, from the use of nuclear weapons has to be measured. In such circumstances even significant civilian casualties may not be excessive in relation to the military advantage achieved.

3. The requirements of necessity and proportionality may nevertheless protect the survival even of an aggressor State. A small-scale armed attack does not give the victim the right to respond by destroying the attacker. Although Professor Dinstein writes that 'once the war is raging, the exercise of self-defence may bring about 'the destruction of the enemy's army,' regardless of the condition of proportionality,' he correctly points out that 'it would be utterly incongruous to permit an all-out war whenever a State absorbs an isolated armed attack, however marginal...

   Proportionality has to be a major consideration in pondering the legitimacy of a defensive war.' (YORAM DINSTEIN, WAR, AGGRESSION AND SELF-DEFENCE 208-209 (3d ed. 2001)).

4. Advisory Opinion on Nuclear Weapons, supra note 1, Dissenting Opinion of Judge Higgins, ~ 21.

   Be that as it may with extreme circumstances of self-defense, it remains certain that all parties have to equally abide by the requirements ofjus in bello.5 In that sense these branches of international law are separate. However, this does not mean that there are no points of contact between jus ad bellum and jus in bello. For example, I find the link between jus ad bellum and jus in bello discussed in Professor Roberts's paper quite new and interesting. Indeed, extreme cases of violation of jus in bello, like massive violations of human rights, as he writes, 'can help to legitimize certain uses of force.' Adam Roberts's conclusion is rather cautious; I would say a lawyerly one even though he is the Montegue Burton Professor of International Relations at Oxford University. He says that massive violations of jus in bello can help (emphasis added) to legitimize certain uses of force. This seems to suppose that other conditions (say, threats to international peace and security) have to be, if not overwhelming, then at least playing a significant role in triggering such uses of force. However, even more importantly, Roberts uses the word 'legitimize' instead of, for example, 'making it lawful.' This seems to indicate that his views on this issue are, if not identical, then and least close to those of Thomas Franck and Nigel Rodley who wrote in the aftermath of the Indian intervention in Eastern Pakistan:

   [U]ndeniably, there are circumstances in which the unilateral use of force to overthrow injustice begins to seem less wrong than to turn aside. Like civil disobedience, however, this sense of superior 'necessity' belongs in the realm of not law but of moral choice, which nations, like individuals, must sometimes make weighing the costs and benefits of to their cause, to social fabric, and to themselves.6

   Professor Franck made a similar comment more than a quarter of a century later observing that 'NATO's action in Kosovo is not the first time illegal steps have been taken to prevent something palpably worse.'7 Bruno Simma, analyzing the Kosovo conflict, believes in the same vein that sometimes 'imperative 5. Here I have to express my reservations to Professor Wedgwood's comment that 'most leaders and publics may in fact believe there is an important link between the legitimate purpose of a war and...