Not all ontological concerns which surround the concept of (customary) international law (CIL) have disappeared, rather they have shifted. Whereas the existence of a genuine international legal system is taken as a ‘given’, questions still remain about its genesis and the position of CIL within it. Some, for example, still question whether we can truly speak of customary international law, while others recast the concept of CIL through a formalist perspective. Accordingly, formalism, in its moderate form, treats formal sources, documents and/or proclamations as ‘better’ tools for both (a) the preservation of existing rules of CIL and (b) the ‘creation’ of new legal rules. At its more extreme, formalism purports the view that (c) IL (or even CIL) finds its genesis only in formal sources, documents or proclamations. While some formalisation is undeniably helpful and even necessary, we should be more critical of this formalist paradigm. In this way, the chapter seeks to respond to these positions through a revival of the legacy of Sir Henry Maine and the evolutionary conception of law for which he laid out the first foundation. By operationalising this conceptualisation, a new vision spawns for CIL: a vision beyond mere formalism.

H. L. A. Hart famously suggested to understand legal systems as consisting not only of primary rules (rules that require or forbid certain conduct) but also of secondary rules (rules that determine how rules are created, changed and abolished). This is enough for law within one system, but it cannot account for relations between different legal systems. For this purpose, the chapter introduces the concept of tertiary rules that determine a legal system’s relation with another legal system. The most fundamental such tertiary rule is the rule of external recognition – the rule with which a legal system recognizes a foreign law as law. But this is not the only tertiary rule – choice-of-law rules and certain other rules also count as tertiary rules. The chapter demonstrates the empirical and theoretical importance of the concept of tertiary rules and discusses other examples.

This chapter addresses core theoretical issues surrounding global/transnational legal pluralism, taking up the work of leading theorists. First, is demonstrates that global legal pluralism is very different from earlier versions of legal pluralism (postcolonial and sociological). Next, is exposes the flaw of overinclusive conceptions of legal pluralism, which appears in the global legal pluralism of Paul Berman, and it explains why theoretical concepts of law cannot solve this flaw. It then addresses the profusion of private and hybrid regulatory forms on the domestic and transnational levels, and marks the line between theory and practice. Thereafter, it exposes problems with the relational concept of law formulated for global legal pluralism by Ralf Michaels, showing why it is unsuitable for many situations of legal pluralism. The approach to transnational legal pluralism the chapter articulates avoids these conceptual problems. It centres on conventionally identified forms of law that vary and change over time, which can be grouped in terms of three categories: community law, regime law and cross-polity law. Finally, it sets forth a handful of specific lessons for a reconstructed transnational legal pluralism.

By mixing conceptual clarification and semantic probes, we seek to underscore the problematic nature of characterizing law as a universal concept. We intend to show that law, in the sense by which it is globally understood today, is the outcome of a contingent experience whose extension to other historical and cultural contexts has been achieved at a huge price: heuristic weakness, analytical vacuity, grammatical incoherence, pluralist dogmatism. First, we examine works dealing with “legal pluralism” and “legalism” to identify the reasons why the term “law,” its conceptual extension, and the attribution of its predicative quality are problematic and badly reflect the gap that can exist between a “legalistic way of thinking” about the world and the existence of law in its contemporary meaning. Second, we specifically address works dealing with “Islamic law” and law in Muslim contexts to try to see what law can be at the margin but also what people make it into, often abusively. Third, we seek to outline the contours of a conceptual inquiry, delimiting its relevance, specifying its limits, taking advantage of its analytical razor, clearing the mist, opening the domain of grammar.

Schauer discusses normative positivism, explaining that this type of positivism comes in two main versions, namely, in the shape of a prescription to legal actors and in the shape of a prescription to legal institutional designers. He argues that a full appreciation of the artefactual nature of law leads to the conclusion that a culture can modify its concept of law in order to make it as useful a concept as possible, and that if normative positivism is a plausible position, it follows not only that choosing a concept of law on moral grounds is a moral position but also that choosing to see the enterprise of legal theory in a normative way itself amounts to a normative position.