David Kretzmer is Professor Emeritus, Hebrew University of Jerusalem and Professor of Law, Sapir Academic College.
Many thanks to the editors of the EJIL for selecting my article for discussion on the blog and to Noam, Gina, Thomas and Mary Ellen for their thoughtful and perceptive comments. These comments provide me with the opportunity of clarifying some of the points I raised in the article and expressing my view about issues that I failed to consider.
The discussion in my article was confined to use of force in exercise of a state’s inherent right to self-defence, recognized in article 51 of the UN Charter. I did not consider humanitarian intervention, nor use of force authorized by the Security Council under article 42 of the Charter. However, Gina is quite right in concluding that my analysis of unilateral use of force by states implicitly rules out unilateral humanitarian intervention. Any decision on such intervention must be a collective one taken by the SC under Chapter VII. ( I shall not discuss the controversial view of the Independent International Commission on Kosovo that there may an intervention which while unlawful is nevertheless legitimate.) While article 42 speaks of forcible action “as may be necessary to maintain or restore international peace and security” I fully accept Mary Ellen’s view that such action must also meet the demands of proportionality.
What is the place of the “narrow proportionality” test in jus ad bellum? Thomas points out that while intimating that this test does indeed have such a place I neglected to develop the issue. Following the line of just war theory, Mary Ellen argues that the very essence of proportionality in jus ad bellum involves “weighing the cost of resort to military force in terms of lives lost and property destroyed relative to the value of the legitimate military end.” While Thomas mentions that there is little, if any, authority on which one can “conclude that the law on the use of force already includes a ‘narrow proportionality’ criterion” it seems to me that such a criterion is inherent in the very notion of proportionality. Hence, as in other contexts in which the means-end proportionality test is employed, some “cost-benefit” analysis must indeed be part of the jus ad bellum test too.