This article focuses on the management of circumstances of calamity generally in IEL, as well as calamity as a necessity in international economic relations in the framework of State Responsibility. The focus on calamity as a necessity defence to State Responsibility is however from a ‘necessity paradigm’—i.e., from the view point of responding effectively to circumstances of calamity, which call for a necessary response, wherein the calamity is the centre of focus. This is in contrast to the stand-point of State Responsibility wherein honouring State Responsibility is central and informs the response to the necessity circumstance (the ‘State Responsibility paradigm’). The necessity paradigm of calamity is grounded mainly on justice and development imperatives, along with the conclusion that the State Responsibility paradigm can be incomplete in its response to the calamity; as well as incoherent from the perspective of the world economic order as a whole. The general focus on calamity in International Economic Law adopted here is with specific reference to its key spheres viz., international monetary and financial law within the framework of the IMF; international trade in the context of the WTO; International Development Law, particularly with reference to international investment practice; and finally with an examination of global economic crisis management.