Due Diligence in International Environmental Law and International Human Rights Law: A Comparative Legal Study of the Nationally Determined Contributions under the Paris Agreement and Positive Obligations under the European Convention on Human Rights

Due diligence is a frequently employed notion in international law, yet much is still to be explored about this concept. This article aims to contribute to an understanding of due diligence obligations in international law, which is useful as it can form the basis for a further clarification of corresponding legal rights of subjects of international law. With this purpose in mind, this article initiates the construction of a working model of due diligence in international law by exploring this notion from two perspectives: an accountability perspective and a regulatory perspective. Subsequently, this article will use this model to compare the operation of due diligence obligations in two branches of international law: international environmental law and international human rights law. In doing so, it will become clear that due diligence contains two core elements: ‘reasonableness’ and ‘good faith’. Moreover, it will become apparent that the operation of due diligence obligations in these two branches has implications for systemic issues in international law. Further research on the operation of due diligence obligations in other branches of international law is therefore recommended.