The creation of obligations under international law by diplomatic assurances issued in the context of expulsion

This study examines whether diplomatic assurances issued from one state to another in the situation of the expulsion of individuals can create obligations under international law. The study is conducted against the background of non-refoulement, the legal duty of states to refrain from expelling individuals to states where they may face a risk of torture, persecution or other serious mistreatment. This obligation prohibits expulsion when the predictable risk to the person surpasses a certain threshold. As part of the risk appraisal, a receiving state may provide “diplomatic assurances” to alleviate the concerns of the expelling state. If these assurances sufficiently mitigate the risk, then nonrefoulement is not implicated. Yet it remains unclear whether such assurances create any obligations under international law. It is often said that diplomatic assurances are merely political pledges, but this casual, overbroad assertion fails to appreciate the subtle differences among assurances as well as the nuances in international practice. This study finds that assurances in fact can create obligations under international law, in certain conditions. In turn, where assurances create obligations, states giving those assurances should incur state responsibility if they mistreat the person contrary to the assurances, opening the door to the traditional means of enforcement. More broadly, if the conditions under which assurances create obligations were explicated and acknowledged in international practice, expelling states may predict with greater confidence that an individual will not be mistreated, and non-refoulement would not be implicated.