Security concerns of states in the aftermath of the 9/11 attacks and the global war on terror have brought the use of diplomatic assurances into the spotlight more than ever. Diplomatic assurances in the cases of expulsion to torture, or simply promises not to torture, have raised substantial questions regarding the legality of this practice in international law. The main reason for this criticism is that this practice is mitigation on the principle of non-refoulement to torture, as the most prominent norm of customary international law or jus cogens. This article scrutinizes the origin and nature of this practice and critically analyses the existing case law encompassing diplomatic assurances for expulsion to torture. Thereafter, this article suggests that a more structured framework, perhaps something like treaties, is needed to strengthen the enforcement and monitoring mechanisms of promises not to torture.