The use of diplomatic assurances in the prevention of prohibited treatment

If most receiving States are already bound by a prohibition of torture by treaty law as well as international customary law of jus cogens quality, what is the added value of a diplomatic assurance? This paper argues that the assurance may add a layer of bilateral obligation to the multilateral obligation erga omnes. It is not inherently more or less binding than universal obligations; the difference lies in available enforcement options. Within the framework of diplomatic assurance, sending States can dictate conditions of monitoring and enforcement that do not follow from existing obligations. This determines whether there is an added value and whether in the individual case an assurance can cancel a risk of prohibited treatment. By elevating an individual case to the diplomatic level, it gains significance. By the same move, however, it becomes vulnerable to the exigencies of foreign relations.