Due diligence is a well-recognized, deliberately flexible standard in international law. It has been introduced to complement the system of state responsibility and the international liability framework of commitments. The latter has provided more detail to the understanding of due diligence. Together, these two systems allow for a comprehensive reading and implementation of due diligence in international law.
Two international legal regimes dictate due diligence requirements: the law on international liability and that of the law of state responsibility. These two regimes have been the focus of the United Nations' (UN) International Law Commission (ILC) since 1947, resulting in two respective distinct work streams.
The role of the ILC is to further the understanding and implementation of international law. While any detailed discussion on the nature, scope, and sources of international law goes far beyond the scope of this Paper, it is worth noting that the idea behind the foundation of the ILC was the understanding, shared by all UN member states, that there is indeed a system of internationally shared values, reflected in universally accepted and adopted norms. Such a normative framework has priority over national laws and regulations. Its core principles can be found in the UNC) -- an international treaty which laid the foundation for the United Nations as an international organization. This founding document is often referred to as the constitution of international law and, indeed, of the international community of states. The basic principles of international law, which lie at the core of international cooperation and legal order, provide context for the argument that has been reiterated in Chapter I of the UNC. They include, for example, the principle of sovereign equality, prohibition on the use of force, and due respect for fundamental rights of the individual (generally referred to as human rights law), which is discussed in more detail below.
The work of the ILC complements that of the UN Security Council and, more significantly, of the International Court of Justice. While non-binding, ILC reports, documents, and draft articles serve as a reiteration of the basic principles of international law as reflected by the UNC. ILC experts review a variety of sources of international law, including universal, regional, and bilateral treaty practice; customary law; judicial decisions; and academic writings to summarize current progress of international law for the practical application by relevant UN bodies. For international and constitutional law scholars, these are a trustworthy and reliable resource for analyzing and summarizing diverse legal practices based on various legal norms and principles.
For the purpose of this Paper, we shall look at the ILC work concerning state responsibility, reflecting the normative standard of Articles 2, 4, and 51, as well as Chapters VI and VII of the UNC.
This abstract has been adapted from the author's introduction.