Military assistance on request and general reasons against force: consent as a defence to the prohibition of force

ABSTRACT Is consent a defence or part of the definition of the prohibition of force? The mainstream answer has been to read (non)consent into the definition of the prohibition. The rule would thus prohibit only non-consensual force. In this article, I challenge this approach. This approach implies that there is no general reason against force in international society, that consensual force is not harmful and does not call for justification. And yet, the use of force, whether internal or international, always harms or threatens harm to international peace – the paramount purpose of the United Nations – so that maintaining international peace must count as a general reason against force. Moreover, international actors offer and expect justifications whenever force is used, including with consent. To reflect the general reason against force, the prohibition must exclude consent from its definition. Consent must be recast as a defence.