Nuclear weapons and the separation of jus ad bellum and jus in bello
Nuclear weapons under international law
Cambridge : Cambridge University Press, 2014
The question addressed is whether use of nuclear weapons, in a manner that violates jus in bello can ever be justified by reason that a state is using force in self-defence or is otherwise acting in compliance with the UN Charter (such as under the authority of the UN Security Council). Section A of this chapter frames the contours of the discussion with preliminary observations regarding use of nuclear weapons in light of the separation principle. Section B puts this discussion into context by examining the implications and the legal and theoretical foundations of the separation principle. Section C analyses the contemporary challenges to the separation principle, beginning with a critique of the ICJ’s Nuclear Weapons Advisory Opinion. The section then analyses the implications of the conflation of ad bellum proportionality with in bello proportionality in doctrine and state practice. It surveys contemporary doctrine, which has increasingly challenged the separation principle, particularly in light of the principle of concurrent application of jus ad bellum and jus in bello. It also examines recent state practice challenging the principle and the practice within the UN Security Council, where, arguably, the subordination of in bello considerations to jus ad bellum has been a feature of recently authorised interventions. Section D highlights areas of law where the separation principle has been reaffirmed, asserting that the ‘conflationist’ trend amounts to misunderstanding and misapplication of the law. It also highlights the contribution of international criminal law and the law of state responsibility to reaffirmation of the separation principle. The chapter concludes that use of nuclear weapons in a manner that violates IHL is also a violation of international law no matter what its legality may be ad bellum.