This book considers how international courts have dealt with challenges to domestic legislation, with an emphasis on the jurisprudence of the World Trade Organization (WTO) tribunals. The WTO is certainly not the only international institution which hears challenges to domestic legislation and, when appropriate, the book also refers to decisions by other international courts such as the European Court of Human Rights.

The book first provides a brief history of international challenges to legislation. Chapter two then introduces the context for analysing challenges to domestic legislation before an international tribunal, the nature of legislation, the application of the inter-temporal principle to domestic legislature as well as the relevant principles of state responsibility. The author then sets the stage for the rest of the book in chapter three by explaining why deference in substantive decision-making by international tribunals has risen in importance as compared to procedural deference. Indeed, the establishment of WTO tribunals cannot be vetoed by the defendant state and the terms of reference are mostly determined by the complainant state. In addition, although international tribunals generally have limited remedies, the WTO system has the power to go beyond the traditional declaration of inconsistency (expressed as a “recommendation”) in dealing with challenges to domestic legislation by imposing less deferential mechanisms for compliance, such as “suggestions”, time limits, and formal compliance procedures.

Decreasing procedural deference means that WTO tribunals are now more minded to exercise substantive deference. The author makes the persuasive argument that international tribunals need to be particularly aware of the need for deference as international tribunals are established and maintained through diplomatic means and gain their legitimacy from the persuasiveness, coherence, and objectiveness of their reasoning. Chapter four then considers substantive deference, in particular, the practical aspects of deference in the context of international challenges to legislation. This chapter examines how deference is expressed by international tribunals in fact-finding and the drawing of inferences from raw facts. Chapter four also considers general concepts of deference in general public international law, such as the doctrine of the reserved domain of domestic jurisdiction and the concept of the margin of appreciation which developed in European regional law. In addition, the chapter also discusses the WTO’s own concept of deference, known as the standard of review. The standard of review relates to the deference that WTO tribunals give to domestic decision-makers. While the concept has been fairly developed in WTO challenges to administrative actions, the author concludes that it is underdeveloped in WTO challenges to legislation and WTO tribunals are largely left to determine the degree of deference to be accorded to domestic legislatures.

The book then suggests that there are three types of legislative characterization that international tribunals adopt to express substantive deference to domestic legislatures. Chapter six first discusses the concept of factor characterization, which the author describes as the characterization of legislation according to its legal operation and its practical operation and purpose, as well as to external standards. In contrast to the second type of legislative characterization known as proportionality characterization, factor characterization does not engage in any express weighing of policy considerations or alternative measures. Instead, the international tribunal engages in a review of the features or factors of the domestic legislation to determine if the legislation is in conformity with international agreements. Generally, deference to the domestic legislature is expressed by the international tribunal when it favours the legal or practical operation of the legislation where the legislating state enjoys considerable deference. As is readily apparent, the legislative purpose is often secondary in factor characterization.

Chapter seven discusses the concept of proportionality characterization. Proportionality arises when domestic legislation is challenged on the basis that it affects a protected legal right or concept such as human health or free trade. In the face of competing purposes, the international tribunal is forced to examine the effectiveness and balance of the domestic legislation that is challenged. Nonetheless, as the author demonstrates through a review of WTO cases, WTO tribunals are generally (with some exceptions) respectful of domestic legislative decisions about proportionality. Despite the least degree of inconsistency doctrine, WTO tribunals are generally slow to conclude that there are better ways for the domestic legislature to achieve its desired purpose than the one that has been adopted by the domestic legislature. Furthermore, in deciding if there are reasonable alternative measures, WTO tribunals also prefer to highlight domestic contradictions than to voice their independent opinion.

Finally, chapter eight considers how international tribunals handle challenges to the certainty of domestic legislation whether it is because the legislation in question is inherently ambiguous or confers wide administrative discretion. Interestingly, the book shows from a review of relevant WTO cases that WTO tribunals are unlikely to defer to assertions about the effects of the legislative environment by the legislating state. Instead, WTO tribunals undertake an in-depth analysis of the legislative environment and the effects on the challenged legislation. For ambiguous legislation to be regarded as WTO-consistent, WTO tribunals would require clear and specific aspects of the legislative environment to be persuaded.

There is at present no coherent legal doctrine for dealing with challenges to domestic legislation before international tribunals. This book is therefore timely in providing a description of how international tribunals, and in particular the WTO, have dealt with challenges to domestic legislation. This book is of interest not only to international lawyers but also to domestic constitution lawyers as international challenges to legislature have an impact on the domestic legal sphere.