The conventional understanding of due diligence in international law appears to be that it is a concept that forms part of primary rules. During the preparatory stages in creating the Articles on Responsibility of States for Internationally Wrongful Acts (ARSIWA), the International Law Commission (ILC) focused on due diligence as though it could have formed part of secondary rules. Despite this process, no due diligence provision forms part of the ARSIWA. Yet a number of the final provisions are based on primary rules. This is because the ILC relied on the method of extrapolation in attempts to create secondary rules. Extrapolation is a method of international law-making by which the output of an analytical process is reproduced in a different form following an examination of its content that exists in other forms. In using this method, the ILC attempted to create secondary rules by extrapolating from primary rules. Yet it did not do so with respect to due diligence. However, due diligence can be formulated and applied differently by using this same method. This article analyses the steps of this process to construct a vision of where international legal practice should venture in the future. In learning from and amalgamating the dominant trends in different areas of international and domestic law, this article proposes that due diligence could exist as a secondary rule of general international law. By formulating and applying due diligence as a secondary rule, there is potential to develop the general international law applicable to determining state responsibility for the conduct of non-state actors.

We can observe some developments that indicate a further strengthening of human rights and the rule of law even after 2001. These developments are puzzling as they occurred despite largely unfavourable scope conditions. This article offers an account of these developments that focuses on dynamics endogenous to the law. These internal dynamics provide a causal mechanism that sets in once a certain threshold of legalization has been reached. We employ the Hartian notion of secondary rules which we think is an especially helpful conceptual tool to analyse the endogenous dynamics of legal systems. To the extent that law is programmed towards consistency, secondary rules become necessary in an environment of rapidly increasing legal density to govern the complexity resulting from this proliferation of norms. Upholding consistency is necessary to maintain the autonomy of law in a Luhmannian sense and the ‘morality’ of the legal system in a Fullerian sense. Our goal is to show this and at the same move beyond an argument of system or normative functionality by identifying causal mechanisms that can explain the law’s built-in drive towards secondary rules, and that are in accordance with broader social science theory. We use some insights from cognitive psychology to develop these causal mechanisms further. While testing these causal mechanisms would be beyond the scope of this paper, we hope to provide the conceptual tools for future empirical research on the dynamics of secondary rule-making and offer some empirical illustrations to demonstrate how dissonance reduction operates in practice.

International legal accountability involves the legal justification of an international actor's performance vis-à-vis others, the assessment or judgment of that performance against international legal standards, and the possible imposition of consequences if the actor fails to live up to applicable legal standards. This article examines questions of accountability in the international legal system through the lens of the state responsibility regime. It begins with an examination of the law of state responsibility and the accountability framework that it provides. By definition, that framework can facilitate only inter-state accountability on the basis of positive legal rules. The article then turns to the increasingly rich variety of other modes of international legal accountability. The rise of these alternative modes reflects the expansion of international law's normative horizons beyond inter-state concerns, the widening of the range of international actors, and the diversification of international law-making and implementation methods. It also reflects the fact that states rarely resort to the law of state responsibility to hold one another accountable for breaches of international law. Thus, while state responsibility remains the “paradigm form of responsibility on the international plane,” it is not clear that it constitutes the paradigm form of legal accountability in contemporary international practice.