The Principle of Proportionality in International Law: Foundations and Variations

Originally based upon the principle of equity, proportionality is predominantly used in the field of human rights protection, the use of force and countermeasures, humanitarian law, maritime boundary law, trade law and investment protection. The article finds that components of proportionality are shared and variably applied in these areas. The main challenge relates to weighing and balancing of interests in judicial review, reflecting upon the varied status and authority of international tribunals. The article submits that proportionality or necessity in terms of assessing the relationship of means and end, seeking least intrusive measures, is well-established and qualifies as a self-standing rule of customary international law. It should be termed strict proportionality. However, The Principle of Proportionality in International Law 629 Journal of World Investment & Trade 18 (2017) 628–672 the component of weighing and balancing interests amounts to a general principle of law and applies in context. It informs the interpretation of the law at hand and is subject to varying standards of review.